c o r t e x x x x ( 2 0 1 1 ) 1e2 2

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Research report

A visual processing but no phonological disorder in a childwith mixed dyslexia

Sylviane Valdois a,b,*, Christel Bidet-Ildei c, Delphine Lassus-Sangosse d, Caroline Reilhac e,Marie-Ange N’guyen-Morel d, Eric Guinet a and Jean-Pierre Orliaguet a

a Laboratoire de Psychologie et Neuro-Cognition (UMR 5105 CNRS), Universite Pierre Mendes France, Grenoble, FrancebCentre National de la Recherche Scientifique, CNRS, FrancecCERCA (UMR 6243 CNRS), Universite de Poitiers, FrancedCentre Referent des troubles du langage, Service de pediatrie, CHU Nord, Francee INSERM U825, Pole Neurosciences, Hopital Purpan, Toulouse, France

a r t i c l e i n f o

Article history:

Received 13 October 2008

Reviewed 4 January 2010

Revised 22 February 2010

Accepted 16 May 2011

Action editor Naama Friedmann

Published online xxx

Keywords:

Developmental mixed dyslexia

Surface dysgraphia

Visual attention span

Reaching movements

Length effect

* Corresponding author. Laboratoire de PsychCentrale BP 47, 38040 Grenoble Cedex 9, Fra

E-mail address: Sylviane.Valdois@upmf-g

Please cite this article in press as: Valdodyslexia, Cortex (2011), doi:10.1016/j.cort

0010-9452/$ e see front matter ª 2011 Elsevdoi:10.1016/j.cortex.2011.05.011

a b s t r a c t

The case study of Martial, a French 9-year-old boy, who exhibits severe mixed dyslexia and

surface dysgraphia is reported. Despite very poor pseudo-word reading, Martial has

preserved phonological processing skills as his good oral language, good phoneme

awareness and good verbal short-term memory show. He exhibited a strong length effect

when reading briefly presented words but no sign of mini-neglect. His letter-string pro-

cessing abilities were assessed through tasks of whole and partial report. In whole report,

Martial could only name a few letters from briefly displayed 5-consonant strings. He

showed an initial-position advantage and a sharper than expected left-to-right gradient of

performance. He performed better when asked to report a single cued letter within the

string but then showed an atypical right-side advantage. The same rightward attentional

bias was observed in whole report when top-down control was prevented. Otherwise,

Martial showed preserved single letter identification skills and good processing of 5-letter

strings when letters were sequentially displayed one at a time. His poor letter-string pro-

cessing thus reflects a parallel visual processing disorder that is compatible with either

a visual attention (VA) span or a visual short-term memory disorder. Martial was further

engaged in a complex reaching movement task involving VA and simultaneous processing.

He performed motor sequences not as a whole but as a succession of independent motor

units, suggesting that his attention was not allocated in parallel to the two to-be-reached

targets prior to movement execution. Against a more basic motor disorder however, he

showed good performance in a task of cyclical pointing movements. The overall findings

suggest that Martial suffers from a visual simultaneous processing disorder that disturbs

letter identification in strings. Instead of being restricted to letter-string processing, this VA

disorder might extend to non-verbal task.

ª 2011 Elsevier Srl. All rights reserved.

ologie et Neuro-Cognition (UMR 5105 CNRS), Universite Pierre Mendes France, 1251 Avenuence.renoble.fr (S. Valdois).

is S, et al., A visual processing but no phonological disorder in a child with mixedex.2011.05.011

ier Srl. All rights reserved.

c o r t e x x x x ( 2 0 1 1 ) 1e2 22

1. Introduction

Although developmental dyslexia was primarily investigated

through group studies, some case studies were conducted

with the aim of showing the existence of dyslexia subtypes

characterized by specific reading profiles. Cases of phonolog-

ical and surface dyslexia were thus described in the child, by

analogy with the forms initially reported in the context of

acquired dyslexia (Marshall, 1984; Snowling, 1981). Children

with phonological dyslexia show selective difficulties in

pseudo-word reading but preserved reading performance on

exception words (Campbell and Butterworth, 1985; Howard

and Best, 1996; Lallier et al., 2010; Snowling and Hulme,

1989; Snowling et al., 1986; Temple and Marshall, 1983). In

contrast, children with surface dyslexia have poor exception

word reading but perform at their grade level in pseudo-word

reading (Brunsdon et al., 2005; Castles and Coltheart, 1996;

Dubois et al., 2007; Goulandris and Snowling, 1991; Hanley

and Gard, 1995; Hanley, et al., 1992; Romani and Stringer,

1994; Valdois et al., 2003).

Although they are well designed for revealing the cognitive

dysfunctions associated to and potentially responsible for the

participant’s reading acquisition disorder (Caramazza, 1986),

case studies provide no information on the prevalence of each

dyslexia subtype in the overall population. To overcome this

gap, group studies were conducted to determine which

proportion of dyslexic children demonstrated a phonological-

like or a surface-like profile. They showed that only a small

proportion of dyslexic children (about one third) showed

reading patterns characterized by a strict dissociation

between exception word and pseudo-word reading. Actually,

most children (from 60 to 76% depending on the studies)

exhibited a mixed pattern in which they were poor on both

exception word and pseudo-word reading (Castles and

Coltheart, 1983; Manis et al., 1998; Sprenger-Charolles et al.,

2000; Stanovitch et al., 1997).

Despite its frequency in the dyslexic population, mixed

dyslexia was only poorly studied. Case DT was reported by

Brunsdon et al. (2002) as a case of developmental mixed

dyslexia on the basis of a severe impairment affecting regular,

irregular and pseudo-word reading. However, DT exhibited an

associated neurological disorder, and his reading problems

occurred secondarily to his brain damage thus questioning its

developmental origin. Lack of interest for mixed dyslexia

profiles probably results from their theoretical interpretation.

Indeed individuals with mixed dyslexia were a priori consid-

ered as presenting with difficulties incorporating character-

istics of both phonological and surface dyslexia subtypes.

Accordingly, the in-depth investigation of prototypical cases

of phonological and surface dyslexia appeared as a necessary

and sufficient condition for the understanding of mixed

profiles.

Within the dual route framework (Coltheart et al., 1993,

2001), mixed dyslexia was typically viewed as resulting from

two distinct dysfunctions (Manis et al., 1998). A difficulty

acquiring some components of the lexical route (global

procedure) combined with difficulties for acquiring one or

more component of the phonological route (analytic proce-

dure) would result in difficulties in reading both familiar

Please cite this article in press as: Valdois S, et al., A visual prodyslexia, Cortex (2011), doi:10.1016/j.cortex.2011.05.011

words and pseudo-words as documented in mixed dyslexia.

Such an interpretation was however disputed because of the

prevalence of mixed profiles within the dyslexic population

(Manis et al., 1998). The over representation of reading disor-

ders resulting from a double deficit was not a priori predicted

by the dual route model. To the contrary, pure forms resulting

from a single route dysfunction were expected to be more

frequent insofar as the development of the two procedures of

reading was supposed to be independent. To account for the

dynamics of reading acquisition, the self-teaching hypothesis

(Share, 1995, 1999, 2004) assumes that the analytic procedure

of reading contributes to the development of the lexical

procedure during reading acquisition. According to Share,

every successful decoding of a new word during text reading

provides an opportunity to acquire this new word ortho-

graphic information. It follows that a dysfunction of the

analytic procedure resulting in poor pseudo-word reading

should further prevent normal functioning of the self-

teaching mechanism, thus resulting in poor familiar word

reading as well. There is also a great deal of evidence that

difficulties in analytic processing typically follow from diffi-

culties acquiring phonological analysis skills such as

phoneme awareness (Vellutino et al., 2004, for a review).

Accordingly, poor phoneme awareness skills leading to delays

in the establishment of the sublexical mapping procedure

would slow down the acquisition of specific orthographic

knowledge, thus resulting in a pattern of mixed dyslexia.

Such an assumption is supported by PDP (parallel distrib-

uted processing) connectionist models of reading (Harm and

Seidenberg, 1999; Plaut et al., 1996; Seidenberg and

McClelland, 1989). Such models indeed postulate that

a single mechanism mapping from orthography to phonology

generates correct output for all types of letter strings (regular

and exception words, as well as pseudo-words). Accordingly,

the probability is high for a mixed pattern to follow from

a single underlying dysfunction. Harm and Seidenberg (1999)

demonstrated through simulations that although a mild

phonological impairment only affected pseudo-word reading,

a more severe phonological impairment resulted in both

pseudo-word and exception-word reading difficulties. These

overall findings suggest that mixed developmental dyslexia

might follow from a single but severe phonological

impairment.

Although developmental dyslexia is typically viewed as

reflecting an underlying phonological impairment (Vellutino

et al., 2004), a number of case studies of children with

specific difficulties in irregular word reading (Brunsdon et al.,

2005; Castles and Coltheart, 1996; Dubois et al., 2007;

Goulandris and Snowling, 1991; Hanley and Gard, 1995;

Hanley, et al., 1992; McCloskey and Rapp, 2000; Romani and

Stringer, 1994; Romani et al., 1999; Valdois et al., 2003) or

peripheral dyslexia (Friedmann and Rahamim, 2007) have

been reported without associated phonological problems,

thus challenging the view that a selective phonological core

deficit is the source of reading disorders in all cases of devel-

opmental dyslexia.

Otherwise, many studies have identified a range of prob-

lems with visual attention (VA) in children with dyslexia (for

reviews see Boden and Giaschi, 2007 or Vidyasagar and

Pammer, 2010). Some of these VA problems have been found

cessing but no phonological disorder in a child with mixed

c o r t e x x x x ( 2 0 1 1 ) 1e2 2 3

in children who further exhibited a phonological disorder

(Facoetti et al., 2006; Hari and Renvall, 2001; Lallier et al., 2010).

However, a VA span disorder e i.e., a deficit in the number of

distinct visual elements that can be processed in parallel in

a multi-element array e was reported in dyslexic children

who demonstrated no phonological problems (Bosse et al.,

2007; Dubois et al., 2010; Valdois et al., 2003, 2004). Reversely,

other dyslexic children exhibited a phonological disorder in

the absence of VA span problems (Bosse et al., 2007). Some

cases were even reported with preserved VA span despite

severe phonological problems and evidence for sluggish

attentional shifting in both the visual and the auditory

modality (Lallier et al., 2010). A study carried out on two large

samples of French and British dyslexic children further

revealed that the VA span disorder contributed to the poor

reading outcome of dyslexic children independently of their

phoneme awareness skills (Bosse et al., 2007). It follows that

some cases of developmental dyslexia, which are clearly not

phonological, exhibit a VA span disorder.

The VA span deficit hypothesis is theoretically based on

the connectionist multi-trace memory (MTM) model of poly-

syllabic word reading (Ans et al., 1998). Within this frame-

work, a VA span disorder is primarily detrimental to irregular

word reading so that developmental surface dyslexia would

arise whenever the VA span is reduced enough to hamper the

entire letter sequence of most words to be processed in

a single step (Valdois et al., 2004). Accordingly, cases of

dyslexic children with a single VA span disorder have been

reported in the context of a reading pattern of surface dyslexia

(Dubois et al., 2010; Valdois et al., 2003). However, analytic

processing requires the VA span to be large enough to process

in parallel all the letters of relevant orthographic units (such

as multi-letter graphemes or syllables). It follows that a VA

span impairment might result not only in difficulties for pro-

cessing words globally but it will further prevent normal

processing of multi-letter orthographic units, thus leading to

the word and pseudo-word reading difficulties that charac-

terise mixed dyslexia. In contrast to previous accounts that

mixed dyslexia would result from either a severe phonological

disorder or a combination of disorders, this theoretical

framework predicts that some cases of mixed dyslexia should

follow from a VA span disorder but preserved phonological

abilities.

In the present study, we will report the case of Martial,

a French child with severe mixed dyslexia. We will first

provide a detailed investigation of his reading and spelling

abilities to assess the efficiency of the analytic and global

procedures of reading/spelling. Both reading procedures are

expected to be impaired in the context of either a phonological

or a VA span disorder. However in spelling, predictions differ

depending on the underlying impairment. Pseudo-word

spelling, which primarily relies on the ability to segment the

dictated pseudo-word into phonemes, should be strongly

impaired following a phonological disorder but mainly

preserved in the context of a VA span disorder. Moreover,

phonological errors are expected in both reading and spelling

following a phonological disorder but regularisation errors in

reading and phonologically plausible errors in spelling should

predominate in case of a VA span problem but preserved

phonological skills. A difficulty to allocate attention to the

Please cite this article in press as: Valdois S, et al., A visual prodyslexia, Cortex (2011), doi:10.1016/j.cortex.2011.05.011

whole word or pseudo-word letter string in reading should

rather result in partial decoding or letter identity errors.

Second, the hypothesis of an underlying phonological

disorder will be assessed. Because the phonological deficit in

developmental dyslexia is typically found in the context of

more general oral language difficulties (Snowling, 2008),

Martial’s oral language skills will be investigated togetherwith

his phoneme awareness and verbal short-termmemory skills.

We will then turn to the assessment of his visual pro-

cessing abilities with a focus on VA span. As in our previous

studies, Martial’s VA span abilities will be assessed through

tasks of whole and partial letter report (Bosse et al., 2007, 2009;

Dubois et al., 2007, 2010; Prado et al., 2007; Valdois et al., 2003).

Even though these tasks require the report of a single letter or

of all of the letters of briefly presented consonant strings, they

cannot be considered as primarily phonological or visual

short-term memory tasks (Valdois et al., in press). Global

report performance is barely affected by a concurrent verbal

short-term memory task (Pelli et al., 2006) and children with

a VA span disorder exhibit similar difficulties in non-verbal

tasks using non-verbal material, against any phonological

interpretation of the disorder (Lobier et al., submitted for

publication). Because we are interested in multi-letter pro-

cessing, the ability to identify individual letters quickly was

further controlled by means of a single letter identification

task. An atypical performance in bothwhole and partial report

tasks was expected as evidence for a VA span disorder.

However, because it involves reporting five letter names, the

whole report task might be sensitive to a phonological or

verbal short-term memory problem. In order to disambiguate

from the visual or phonological interpretation of poor

performance on this task, Martial was further administered

a sequential processing task requiring the report of as many

letters as possible from series of five consonants which were

displayed in turn, one at a time, on the computer screen. A

verbal short-term memory problem should result in poor

performance on both the whole report and sequential report

tasks whereas performance in sequential report would be

preserved following a VA span e thus a simultaneous visual

processing e disorder (see Lassus-Sangosse et al., 2008 for

a similar account).

Another important issue concerns the relationship

between reading and VA span. In reducing the amount of

information available for processing, a VA span disorder

would further result in a length effect on words. This

hypothesis was assessed in Martial who was asked to read

regular words varying in length. Because regular words can be

read accurately following analytic processing (thus relying on

shorter units compatible with a reduced VA span), wordswere

briefly presented on a computer screen to prevent eye move-

ments and trigger simultaneous processing. Martial was ex-

pected to show a strong length effect on this task if only a few

letters were extracted at a time. Probability of reporting letters

as a function of their serial position in the word was further

computed to assess the existence of an attentional imbalance

between the left and right visual hemi-fields.

The last part of the investigationwas done as an attempt to

show that the VA span disorder in Martial extended to non-

verbal material and non-reading tasks as far as parallel pro-

cessing was involved. For this purpose, Martial was asked to

cessing but no phonological disorder in a child with mixed

c o r t e x x x x ( 2 0 1 1 ) 1e2 24

perform a sequential reaching movement towards two pre-

determined targets. Interest of this task resides in the fact that

sequential reachingmovements require parallel processing of

the to-be-reached targets so that a VA span disorder might be

expected to impact performance on this task. Motor antici-

pation was in particular investigated as reflecting parallel

processing. Indeed, motor anticipation in the execution of

sequential reaching movements (Louis-Dam et al., 1999;

Orliaguet et al., 1997) is characterized by changes in the

movement duration of the first component of the sequence

according to the spatial constraints of forthcoming compo-

nents. According to Baldauf et al. (2006; see also Deubel and

Schneider, 2004), the first and second movement targets are

selected temporally in parallel when a sequence of two

movements is prepared. During movement preparation and

well before the onset of the first movement, VA is allocated in

parallel to the secondmovement target to allow integration of

the second target size and location into the movement

program, thus resulting in motor anticipation. Simultaneous

processing of the different movement targets is thus required

for the execution of a smooth and fluent sequential reaching

movement. We asked Martial to perform a sequence of two

goal-directed movements. The size of the second to-be-

reached target was varied so that variations in the kine-

matics of the first movement (i.e., motor anticipation) were

expected if VA had been allocated in parallel to the second

target. A VA span disorder was expected to affect the execu-

tion of the movement in preventing motor anticipation.

However, because motor anticipation can be disturbed

following basic motor disorders, a control task of cyclical

reaching movements was further administered. The absence

of motor anticipation in sequential reaching movements but

preserved performance in cyclical reaching movements

would exclude a motor disorder while supporting a simulta-

neous visual processing disorder.

1 The ‘Alouette’ Reading test requires children to read a 265-word text as quickly and accurately as possible. The textincludes a number of unfamiliar words and prevents guessingstrategy. The reading level is established from both readingaccuracy and reading speed.

2. Case report

Martial, a right-handed French boy, was 8 years 10 months at

the time of the initial assessment. He was in third grade. He

did not have any history of neurological disorder or psychi-

atric illness. He had received conventional instruction but

complained of very severe reading and spelling difficulties. His

parents described him as a very clever child who developed

normal oral language skills very early. Martial started primary

school at 6, after three years of nursery school during which

no difficulty was noted. He was taught to read through

a combination of whole language and phonics tuition

methods. He was then admitted in second grade but repeated

this grade because of his severe reading and spelling difficul-

ties. His father reported similar difficulties with reading/

spelling acquisition.

Administration of the Wechsler Intelligence Scale for

Children revealed that Martial had a full scale IQ of 132, with

a verbal IQ of 125 and a performance IQ of 131. His perfor-

mance on a standardised test of reading (The “Alouette” test:

Lefavrais, 1965) showed that he achieved a reading age (RA) of

6 years 6 months, thus revealing a delay of 28 months in

reading acquisition. Martial thus performed considerably

Please cite this article in press as: Valdois S, et al., A visual prodyslexia, Cortex (2011), doi:10.1016/j.cortex.2011.05.011

below average for his age and showed a large discrepancy

between his actual achievement in reading and his expected

achievement based on his intelligence. He further exhibited

severe spelling difficulties with a performance below the 5th

percentile on the Lobrot (1980) test. The administration of the

CONNERS questionnaire (Loney and Milich, 1985) did not

reveal any symptom of attention-deficit/hyperactivity

disorder. On the conventional tests of line bisection or

picture copying, Martial showed no clinical signs of spatial

neglect. Visual acuity was normal but a slight disconjugate

gaze had been noted when he was 8. He benefited from an

orthoptic remediation and his oculo-motor abilities were

normal at the time of testing. Martial nevertheless performed

poorly on a task of target cancellation among distracters (“The

Bells Test”, Gauthier et al., 1989). He was very slow and only

cancelled 25 bells out of 35 in 2 min, scoring at the 5th

percentile of children matched for chronological age (CA).

However here again, performance was not characterized by

a left-right asymmetry, against a neglect interpretation. The

evaluation further revealed no sign of ideomotor, ideational or

constructional apraxia. Visuo-spatial short-termmemorywas

preserved with a score above the 90th percentile on the CORSI

Test. Martial further had normal auditory perception and

demonstrated excellent abilities to discriminate nonsense

syllables differing by a single phonetic feature (e.g., /pa/-/ba/;

Martial¼ 14/14, mean CA controls¼ 13.5; SD¼ 1.3).

The experimental investigations described hereafter

occurred between the ages of 9 years 4 months and 10 years

3 months. No significant improvement was noted in his

reading/spelling during the time of assessment. Martial’s

performance in reading and spelling was compared to that of

two CA and RA matched control groups: a group of 25 control

children matched for CA (mean CA¼ 109.1 months, SD¼ 1.9;

mean RA¼ 107.9 months, SD¼ 8.7) and a group of 25 non-

dyslexic children of the same RA (mean CA¼ 78.6 months,

SD¼ 1.53; mean RA¼ 78.2 months, SD¼ .81) as established

from the “Alouette” reading test.1 It is noteworthy that RA

participants were assessed after only 6 months of formal

literacy instruction, thus being very beginning readers. Chil-

dren in both control groups were not matched in IQ with

Martial since most children with a similarly high intellectual

efficiency demonstrated a far higher reading level than their

peers.

2.1. Statistical analysis

We assessed the difference between Martial’s performance

and the control groups’ mean performance using a method

based on the t-distribution proposed by Crawford and Howell

(1998) which is more robust than traditional testing based on

z-scores. In agreement with Crawford and Garthwaite (2002)

significance was assessed through one-tailed tests. Essen-

tially, this method is a modified independent samples t-test in

which the individual is treated as a sample of one subject and

cessing but no phonological disorder in a child with mixed

c o r t e x x x x ( 2 0 1 1 ) 1e2 2 5

therefore does not contribute to the within group variance.

Performance patterns in whole and partial report were ana-

lysed in Martial and the control groups. We performed trends

analyses to examine the best fitting position functions in each

group (Martial vs CA- or RA-group). Evidence for different

position functions was taken as evidence for a differential

position effect in Martial and the controls, thus enabling

individual comparisons using t-tests at the position level.

2 Error rates on words and pseudo-words cannot be directlycompared since target items were not a priori designed to havethe same rate of contextual graphemes or letters with visualneighbours.

3. Reading and writing

3.1. Reading

Method: Martial’s reading performance was assessed using

tasks of text reading, single word reading and mapping rules

knowledge.

- In the text reading task, Martial was asked to read a text

aloud during 2 min (“Petit Monsieur” from the ODEDYS Test,

Jacquier-Roux et al., 2002).

- Word and pseudo-word reading performance was assessed

using lists of 20 high frequency (HF) and 20 low frequency

(LF) regular and irregular words, and a list of 40 pseudo-

words matched on length and orthographic structure to

the regular words (see the list of items in Appendix). Regular

and exception word frequency was 126 and 120 per million

respectively for the HF lists, 18 and 12 per million for the LF

lists (from MANULEX, a database from French elementary

school-readers, Lete et al., 2004). Each list of 20 items was

printed on a white sheet of A4 paper, in a lower-case format

(Times, 14 pt). Martial was asked to read the items aloud as

quickly and accurately as possible. He was informed of the

nature of the items (i.e., real words or pseudo-words) before

beginning to read. For each list, the number of items accu-

rately read and the time taken to complete the list were

recorded. Because of their very young age, the RA controls

only performed the HF lists of regular and irregular words

and one pseudo-word list.

- To assess more directly whether Martial knew

graphemeephoneme mapping rules, he was further pre-

sented with the isolated French graphemes (e.g., “au”, “in”,

“ph”) and asked to sound them out.

Results: Results are provided in Table 1. Martial’s perfor-

mance was significantly lower than that of CA controls on all

the reading tasks, whether considering accuracy [regular

HF words: t(25)¼�20.8, p¼ 1.32E-17; regular LF words:

t(25)¼�5.2, p¼ .0000107; irregular HF words: t(25)¼�6.4,

p¼ .0000005; irregular LFwords: t(25)¼�3.4, p¼ .0012; Pseudo-

words List 1: t(25)¼�7.1, p¼ .000000115; Pseudo-words List 2:

t(25)¼�4.9, p¼ .0000002] or reading rate [regular HF words:

t(25)¼ 251.1, p¼ 2.36E-44; regular LF words: t(25)¼ 24.3,

p¼ 3.23E-19; irregular HF words: t(25)¼ 47.8, p¼ 2.11E-26

irregular LF words: t(25)¼ 21.6, p¼ 5.69E-18; Pseudo-words List

1: t(25)¼ 27.3, p¼ 2.01E-20; List 2: t(25)¼ 20.5, p¼ 1.83E-17]. His

performance in single word and pseudo-word reading did not

significantly differ from the mean performance of RA controls

except on two features. Martial read fewer words per minute

than RA controls during text reading [t(25)¼�6.6,

Please cite this article in press as: Valdois S, et al., A visual prodyslexia, Cortex (2011), doi:10.1016/j.cortex.2011.05.011

p¼ .0000003]; As compared to RA controls, he made a signifi-

cantly higher proportion of regularisation errors [t(25)¼ 2.4,

p¼ .013] when reading irregular words. The rate of regular-

isation errors tended to be lower inMartial than in CA controls

[t(25)¼�1.70, p¼ .051] because of additional visual errors.

A qualitative analysis of the type of errors produced on

regular words and pseudo-words (errors are listed in

Appendix) revealed a high proportion of visual errors (79% and

75% on regular words and pseudo-words respectively). In the

same way, most of the non-regularisation errors (70%) on

irregular words were visual errors. We classified his visual

errors into letter identity errors resulting from confusions

between visually similar letters (e.g., “b”e“d”: par-

don/ parbon; “n”e“u”: jaloux/ jalon), partial decoding errors

which are characterized by the omission of some of the target

letters (e.g., vague/ vagu; escroc/ escoc), letter order errors

(e.g., paon/ pano; tandir/ tanidr), parsing errors in which

a complex target grapheme is parsed into shorter graphemes

(e.g., ai-vron/ a-i-vron) and contextual errors in which

a contextual sensitive grapheme is produced without

consideration of the surrounding context (e.g., asil/ /a-s-il/

instead of /azil/). Some more complex errors, which might

have resulted from a mixing of different visual error types,

were also observed on both words (e.g., baril/ bain, agen-

da/ agrande) and pseudo-words (e.g., glon/ golin, tauba-

ge/ tanbange). They were classified in the “other” category.

Fig. 1 shows the distribution of these different types of visual

errors on words (regular and irregular) and pseudo-words.

Partial decoding errors (38%) and letter identity errors (24%)

predominated in word readingwhereasMartial only produced

a few letter order (6%) and contextual errors (6%). Half

complex errors (27%) resulted in the production of another

real word that shared common letters with the target but was

not semantically related (e.g., baril, barrel/ bain bath; elec-

tron electron/ ecole school; orchestre orchestra/ fourchette

fork).

Partial decoding and letter identity errors (32% and 14%

respectively) were also frequent on pseudo-words and the

proportion of contextual errors was relatively high (25%).2 As

previously, letter order errors only occasionally occurred (7%)

and only one parsing error was observed. Importantly, Martial

showed no confusion between phonologically similar but

visually dissimilar letters in either word or pseudo-word

reading.

Martial scored 41/46 in the single grapheme reading task,

well within the range of non-dyslexic children of the same CA

(mean¼ 41.3; SD¼ 3.7). His few errors occurred onmulti-letter

graphemes and context sensitive mapping rules. Multi-letter

graphemes were erroneously decoded because of visual

errors (e.g., gn/ gu; oin/ ain; ion/ oi).

3.2. Spelling and copying

Method: Martial was administered tasks of single word and

pseudo-word spelling, and copying.

cessing but no phonological disorder in a child with mixed

Table 1 eMartial’s performance in reading (accuracy and speed), spelling (accuracy), and copying (number of words copiedin 2 min and number of letters processed per gaze lift), as compared to CA and RA controls.

Task Martial CA controls Mean score (SD) RA controls Mean score (SD)

Text reading

Number of words/2 min 16 232.9 (32.30)*** 36.2 (12.70)*

Error rate (%) 37.5 1.8 (1.3)*** 33.9 (18.4)ns

Single item reading

HF regular words

Accuracy (/20) 10 19.72 (.46)*** 7.64 (4.71)ns

Speed (sec) 137 16.04 (3.21)*** 140.91 (56.20)ns

LF regular words

Accuracy (/20) 5 17.36 (2.30)***

Speed (sec) 137 21.82 (4.65)***

HF irregular words

Accuracy (/20) 4 17.91 (2.10)*** 4.48 (3.27)ns

Speed (sec) 205 17.22 (3.85)*** 148.10 (55.7)ns

LF irregular words

Accuracy (/20) 0 12.20 (3.55)**

Speed (sec) 143 23.90 (5.40)***

Regularisation errors (%) 63.9 88.2 (14.0)* 18.9 (18.5)*

Pseudo-words (List 1)

Accuracy (/20) 5 17.12 (1.69)*** 4.81 (4.2)ns

Speed (sec) 116 22.00 (3.38)*** 135.4 (47.9)ns

Pseudo-words (List 2)

Accuracy (/20) 7 16.60 (1.9)***

Speed (sec) 126 25.61 (4.8)***

Spelling

Consistent words (/10) 0 8.5 (1.4)*** 6.2 (2.6)*

Inconsistent words (/10) 0 7.9 (1.8)***

Exception words (/10) 0 5.6 (2.2)* 3.6 (1.9)*

Phonologically plausible errors (%) 70 (93) 72.6 (9.3)ns 53.3 (20.7)*

Pseudo-words (/20) 10 (18) 16.44 (4.1)ns 3.44 (4.26)ns

Copying

Number of Words 8 29.1. (4.65)*** 8.64 (2.1)ns

N of Letters / Gaze Lift 1.1 4.65 (2.03)* 1.37 (.3)ns

Phonologically plausible errors were scored according to a stringent (and lenient) criterion. *¼ p< .05; **¼ p< .01; ***¼ p< .001; ns¼ non-

significant.

c o r t e x x x x ( 2 0 1 1 ) 1e2 26

- In the single word spelling task, Martial was asked to spell

under dictation a list of 30 words (from the ODEDYS Test).

The list included 10 consistent words that could be spelled

accurately by application of the most frequent

0

5

10

15

20

25

30

35

40

Partial Identity Context Order Parsing OtherVisual error types

Erro

r R

ate

WordPword

Fig. 1 e Distribution of each type of visual errors in word

and pseudo-word reading.

Please cite this article in press as: Valdois S, et al., A visual prodyslexia, Cortex (2011), doi:10.1016/j.cortex.2011.05.011

phonemeegrapheme conversion rules (e.g., /ORdyR/

/ ordure), 10 inconsistent words including at least one

phoneme associated to a relatively infrequent grapheme

(e.g., /seRpa// serpent) and 10 exception words which

could only be accurately spelled through activation of

specific word knowledge (/m4sj4//monsieur).

- Pseudo-word spelling was assessed using two lists of 10 bi-

syllable and 10 tri-syllable pseudo-words from the ODEDYS

Test.

- For the copying task, Martial was asked to copy a text during

2 min. During copying, the examiner recorded the number

of gaze lifts done to pick up more information on the text in

order to continue copying it (see Kandel and Valdois, 2006

for more details on the method). The total number of

words accurately copied during the allotted time was

measured together with the number of letters processed at

each gaze lift (i.e., total number of copied letters divided by

the number of gaze lifts).

Results: As shown on Table 1, Martial was unable to spell

accurately any of the dictated words. His performance was

well outside the range of CA-matched control children [on

consistent words, t(25)¼�5.9, p¼ .0000016; inconsistent

cessing but no phonological disorder in a child with mixed

c o r t e x x x x ( 2 0 1 1 ) 1e2 2 7

words, t(25)¼�4.3, p¼ .00011; and exception words, t(25)¼�2.5, p¼ .009] and was significantly lower than that of RA

controls for the consistent and exception words [t(23)¼�2.3,

p¼ .0143 and t(23)¼�1.8, p¼ .0382 respectively]. A qualitative

analysis of his errors (see Appendix) was performed to

determine the rate of phonologically plausible errors. Two

different criteria were used. An error was considered as

phonologically plausible error (PPE) according to a ‘stringent

criterion’ if the written word sounded as the dictated word

when applying the most frequent graphemeephoneme

conversion rules in context (according to this criterion “S” is

pronounced /z/ between two vowels, and a final “T” ismute). A

second ‘lenient criterion’ was further used according to which

spellings were considered as phonologically plausible when-

ever graphemes could be pronounced as the dictated

phonemes without consideration for mapping frequencies or

orthographic context (according to this criterion “S” can be

pronounced /s/ between two vowels, and a final “T” corre-

sponds to /t/). Actually, we were here interested in those

errors reflecting good phonological processing. Lax phono-

logically plausible errors in fact reflect Martial’s ability to

segment spokenwords into phonemes, without consideration

for the conventional orthographic rules which require the

phoneme /s/ to be converted in “SS” between two vowels or

the phoneme /t/ to be written “TE” at the end of French words.

The error analysis revealed that 70% and 93% errors were

phonologically plausible according to the stringent and lax

criteria respectively. In the absence of normative data on this

task, Martial’s performance was compared to that of 3rd and

1st grade children as reported in Martinet and Valdois (1999)

for very similar words. Normal 3rd grade readers were re-

ported to make 72.6% phonologically plausible errors on the

average whereas 1st grade children only made 53.3% such

errors. Martial therefore demonstrated good abilities to spell

words as they sound.

Martial pseudo-word spelling performance is reported in

Table 1, his misspellings are listed in the Appendix. When

using the stringent criterion, Martial’s performance did not

significantly differ from that of the control groups [CA:

t(25)¼�1.55, p¼ .067; RA: t(23)¼ 1.51, p¼ .073]. He however

obtained a higher score when applying the lax criterion, well

above RA matched controls’ performance and well within the

range of CA controls. The overall results thus demonstrate

Fig. 2 e Illustration of Martial’s handwriting perfo

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very good abilities to segment dictated pseudo-words into

phonemes.

Lastly, Martial performed very poorly on the copying

task (see Table 1). He copied only 8 words (corresponding to

13 syllables) in 2 min and made 30 gaze lifts. On average,

only 1.1 letters were processed at each gaze lift. His

performance was slightly below that of children of the same

CA [t(25)¼�1.7, p¼ .05] but did not differ significantly from

the performance of RA matched controls [t(25)¼�.8,

p¼ .20]. The task further revealed a difficulty to follow the

line when writing and a very dysfluent gesture organization

(see Fig. 2). Letters were ill-formed and frequently over-

lapped as a consequence of being juxtaposed one at a time.

Similar handwriting disorders were observed in all the

spelling tasks.

3.3. Summary

Martial exhibits a mixed reading profile characterized by

dramatically poor performance (accuracy and speed) on both

regular and irregular words and pseudo-words as compared to

control children matched for CA. He thus exhibits a mixed

developmental dyslexia pattern. Most erroneous responses in

reading resulted from visual errors consisting in partial decod-

ing of the word letter string, in confusions between visually

similar letters or a tendency to translate contextual graphemes

without considerationof the surroundingcontext.Although the

same types of visual errors occurred on both regular and irreg-

ular words and pseudo-words, a good proportion of errors on

irregular words were regularisation errors.

His reading disorder is associated with a very severe word

spelling disorder e since he was unable to spell any dictated

word accurately e but relatively preserved pseudo-word

spelling. Most spelling errors on words were phonologically

plausible. His spelling performance thus conforms to that

typically reported in surface dysgraphia.

The comparison with a group of very beginning readers of

the same reading level however revealed that Martial per-

formed within the range of RA controls in tasks of single word

or pseudo-word reading, and in the copying task. Such

a similarity of performancewith younger children of the same

RA is typically interpreted as demonstrating a general reading

or learning delay. Against a general delay interpretation

rmance in copying and spontaneous writing.

cessing but no phonological disorder in a child with mixed

c o r t e x x x x ( 2 0 1 1 ) 1e2 28

however, Martial demonstrated worse performance than RA

controls on some tasks but better performance on other tasks.

On one hand, he performed significantly poorer than RA

controls when asked to read a meaningful text as quickly as

possible and demonstrated significantly lower word

spelling performance. But to the contrary, his knowledge of

the graphemeephoneme/phonemeegrapheme correspon-

dences was far better than that of RA controls. Actually, his

rate of regularisation errors in reading and of phonologically

plausible errors in spelling was well within the range of chil-

dren of the same CA, as was his meta-knowledge of the

mapping rules. These latter features do not fit well with the

hypothesis of a general delay and rather suggest an ill-

balanced development as typically found in developmental

dyslexia. The next part of the assessment investigates the

existence of associated phonological or VA span disorders in

Martial.

4. Phonological and visual processing skills

4.1. Phonological processing

4.1.1. Oral language skillsAccording to the phonological hypothesis of dyslexia

(Snowling, 2000), dyslexic children have poorly specified

phonological representations yielding picture naming diffi-

culties, problems in spoken word identification and poor

repetition abilities. Therefore, Martial was submitted to

a number of oral language tasks to evaluate these different

skills and assess the potential existence of an associated

verbal disorder.

Method: Martial was submitted to a battery of tasks

assessing oral language skills: his level of oral vocabulary was

estimated through the EVIP Test (French version of the Pea-

body Picture Vocabulary Test, Dunn et al., 1993), two tests of

oral picture naming (ELO: Khomsi, 2001; DO80: Deloche et al.,

1997) and a test of spoken word definition (TVAP: Deltour

et al., 1998). His level of oral sentence comprehension was

investigated using the ECOSSE Test (Lecocq, 1993). Two tasks

of word and pseudo-word repetition were taken from the

BALE Test (Jacquier-Roux et al., unpublished). A longer task of

pseudo-word repetition was further proposed that included

long pseudo-words with consonantal clusters. His perfor-

mance in semantic and phonemic fluency was further

Table 2 e Martial’s oral language performance on standardise

Tasks Raw Score Percentile

Oral vocabulary

EVIP 134 98

Word definition

TVAP (/30) 27 75

Lexical evocation

DO80 (/80) 74 95

ELO (/50) 43 95

Comprehension

ECOSSE (/20) 17 95

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measured through two tasks that required reporting as many

animal names or as many words beginning with /p/ as

possible during 1 min.

Results: Martial’s performance on these different stand-

ardised tasks is presented in Table 2 together with the corre-

sponding percentiles established from children of the same

CA. Martial scored at the top-level of CA children onmost oral

language tasks, a performance well in accordance with his

high verbal IQ. His high level of oral vocabulary in picture

identification (EVIP) and word definition (TVAP) suggests the

absence of vocabulary acquisition problems. His good

performance in lexical evocation (DO80, ELO) shows his ability

to explicitly activate phonological information from long-term

memory. Further, he never manifested word finding difficul-

ties and never made any phonological paraphasia. His high

level of oral sentence comprehension (ECOSSE Test) further

supports good spoken word identification skills. Phonological

processes are critical to pseudo-word repetition. Obviously,

the excellent performance of Martial even when required to

repeat polysyllabic pseudo-words including consonant clus-

ters provides evidence against phonological problems.

However, Martial performed below the expected level in

phonemic fluency while scoring on the average in semantic

fluency. His score was similar to that of younger children of

the same RA when asked to report words beginning with

a particular sound.

4.1.2. Phoneme awareness and phonological memoryAccording to the phonological theory of developmental

dyslexia, phoneme awareness e the sensitivity to the sound

structure of spoken words- and verbal short-term memory

are expected to be severely impaired in dyslexic

individuals.

Method: To further assess his phonological skills, Martial

was submitted to tasks of phoneme awareness and phono-

logical memory.

- In the Phoneme deletion task, Martial was asked to delete the

first sound of 20 spoken words and produce the resulting

pseudo-words (e.g., /uti/ "outil"/ /ti/; /plakar/ "plac-

ard"/ /lakar/).

- In Phoneme segmentation, a set of 15 words was presented

auditorily toMartial who had to successively sound out each

of the word constitutive phonemes (e.g., /kado/ “cadeau”

gift/ /keaedeo/).

d tests.

Tasks Raw Score Percentile

Repetition

Words (/16) 16 98

Pseudo-words (/20) 20 98

Pseudo-words (/92) 92 98

Lexical fluency

Semantic 13 60

Phonemic 5 15

cessing but no phonological disorder in a child with mixed

c o r t e x x x x ( 2 0 1 1 ) 1e2 2 9

- The Spoonerisms task required exchanging the first

phonemes of two heard words (e.g., /banan/ e /fisel/

/ /fanan/ e /bisel/). Responses were always two pseudo-

words (for a detailed description of the tasks, see Lassus-

Sangosse et al., 2008 and Bosse and Valdois, 2009).

- The Acronyms task of the BELEC battery (Mousty et al., 1994)

was further administered in an abbreviated version (10

trials). Two words were successively pronounced by the

experimenter (one word per second). Martial was required

to extract the first phonemes of each word and combine

them to produce a syllable.

- The digit span task (forward and backward) from the WISC

was further administered.

For each task, Martial was given a set of practice items for

which he received feedback. No feedback was provided on the

experimental items.

Results: As shown in Table 3, Martial performed within the

average of CA controls on the whole set of phoneme aware-

ness tasks [deletion: t(25)¼�.2, p¼ .42; segmentation:

t(25)¼�.07, p¼ .47; spoonerisms: t(25)¼�.68, p¼ .25; acro-

nyms: t(25)¼�.38, p¼ .35]. His performance was well above

that of the younger controls on the two tasks of deletion

[t(25)¼ 3.22, p¼ .002] and segmentation [t(25)¼ 2.33, p¼ .014]

but did not differ on the easier task of acronyms [t(25)¼ .77,

p¼ .22]. The spoonerism task was too difficult for RA controls.

Overall, Martial’s performance demonstrates good ability to

identify and manipulate the phoneme units of spoken words.

With respect to verbal short-termmemory, Martial performed

well within the range of non-dyslexic CA controls.

4.2. Visual processing

Martial was administered two experimental tasks of whole

and partial report (Bosse et al., 2007) and two control tasks of

single letter identification threshold and sequential report

(taken from Lassus-Sangosse et al., 2008). Good performance

on these later tasks would reflect good processing of indi-

vidual letters, quick retrieval of letter names in long-term

Table 3 e Martial’s performance in phoneme awarenessand visual processing tasks as compared to CA and RAcontrols.

Tasks Martial CA controls RA controls

Phoneme awareness

Phoneme Deletion (/20) 14 14.81 (4.4)ns 3.76 (3.1)**

Acronyms (/10) 6 7.00 (2.7)ns 3.68 (2.9)ns

Phoneme segmentation

(/15)

7 7.31 (4.6)ns 1.76 (2.2)*

Spoonerisms (/10) 5 6.62 (2.4)ns e

Visual processing

Visual attention span

Global report (/100) 56 78.9 (9.8)** 44.8 (9.5)ns

Partial report (/50) 41 38.1 (5.6)ns 27.2 (8.0)*

Control tasks

Sequential report (/100) 67 66.1 (11.7)ns

Letter identification

threshold

67 60.6 (20)ns 95.1 (25.9)*

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memory and the absence of verbal short-term memory

problems.

During the assessment, different position patterns were

obtained in whole and partial report with a tendency to better

report the initial-position letter in the whole report condition

but the letters on and at the right of fixation in partial report.

Because the initial letteradvantagemighthave resulted froman

endogeneous top-down attentional bias related to the direction

of reading, performance inwhole report was recorded a second

time using different instructions.Whereas Martial was initially

asked to report as many letters as possible, as typically done in

our previous studies, during the second assessment he was

asked to report first the letters hemore easily perceived. Finally,

a single word reading task under time pressure was adminis-

tered to assess whether length and positional effects charac-

terized Martial’s word reading performance.

4.2.1. VA span assessment

4.2.1.1. WHOLE AND PARTIAL REPORT. The participants were

assessed using two tasks of whole and partial letter-report

designed to estimate the number of distinct letters that

could be extracted in parallel from a brief visual display. The

tasks required the report of a single letter or of all of the letters

of briefly presented consonant strings.

Stimuli: Random 5-letter strings (e.g., R H S D M) were built

up from 10 consonants (B, P, T, F, L, M, D, S, R, H). The letters

were presented in upper-case (Geneva, .8� high) in black on

a white background. The strings contained no repeated

letters. The distance between adjacent letters was of .57� in

order to avoid lateral masking. The whole line subtended an

angle of approximately 5.4�. Twenty 5-letter strings were

successively presented in whole report; each letter was used

10 times (twice in each position). Fifty random 5-letter strings

were presented in partial report. Each letter occurred 25 times

and each appeared five times in each position.

Procedure: At the start of each trial, a central fixation point

was presented for 1000 msec followed by a blank screen for

50 msec. A letter stringwas then presented at the centre of the

display for 200 msec, a duration which corresponds to the

mean duration of fixations in reading, long enough for an

extended glimpse, yet too short for a useful eye movement. In

whole report, the participants’ task was to report verbally all

the letters immediately after they disappeared. In partial

report, a probe e a vertical bar e indicating the letter to be

reported was presented for 50 msec, 1.1� below the target

letter, at the offset of the letter string. Each letter was used as

target once in each position. Participants were asked to report

the cued letter only. In both tasks, the experimenter pressed

a button to start the next trial after the participant’s oral

response. Eye movements were not monitored, but the

requirement of central fixation was strongly emphasized and

repeated at regular intervals during the experiment. The

experimental trials were preceded by ten training trials for

which participants received feedback. The dependent

measures were the mean number of letters accurately re-

ported (identity not location) across the 20 trials (Max¼ 100) or

across the 50 trials (Max¼ 50) in the global and partial report

tasks respectively. Response profiles across positions were

also taken into account.

cessing but no phonological disorder in a child with mixed

c o r t e x x x x ( 2 0 1 1 ) 1e2 210

Results: In whole report (Table 3), Martial reported signifi-

cantly fewer letters than CA controls [t(24)¼�2.29, p¼ .015]

but his performance did not significantly differ from that of

very beginning readers. His ability to identify letters according

to their position in the string is illustrated in Fig. 3a. Martial’s

whole report profile is well captured by a linear function

(accounting for 90% of variance), as for CA controls. However,

the slope of the function tends to be higher in Martial than in

CA controls [slope¼�3.9 vs �2.23; t(24)¼�1.65; p¼ .056] sug-

gesting a sharper drop of performance across positions and

a stronger left bias than CA controls [.58 vs .25; t(24)¼ 2.4,

p¼ .012]. Performance significantly differed from that of

CA controls in positions P2 [15 vs mean¼ 19.2, SD¼ .95;

t(24)¼�4.3; p¼ .00011], P4 [4 vs mean¼ 12.5, SD¼ 3.7; t(24)¼�2.25; p¼ .017] and P5 [5 vs mean¼ 11.76, SD¼ 3.7; t(24)¼�1.78; p¼ .044] so that Martial only reported letters in the

initial position and on the fixation point (in positions P1 and

P3) at the level of CA controls. His global report profile did not

differ significantly from that of RA controls.

In partial report (Fig. 3c), Martial’s overall score was similar

to that of CA controls [t(25)¼�.23, p¼ .41] and only tended to

differ from that of very beginning readers of the same reading

level [t(25)¼ 1.68, p¼ .053]. However, as shown in Fig. 2,

Martial’s performance was characterized by a very atypical

Global report

02468

10121416182022

P1 P2 P3 P4 P5

Position in the string

Co

rre

ct re

po

rt

RACAMartial 1Martial 2

Partial report

0123456789

1011

P1 P2 P3 P4 P5Position in the string

Co

rrect rep

ort

RACAMartial

a

b

Fig. 3 e Martial’s number of correct letter identification

(filled symbols) according to their serial position in the

string in the two conditions of global report (a) and partial

report (b) as compared to the performance of two groups of

non-dyslexic children matched for CA (open squares) or RA

(open triangles). Performance in global report is provided

when Martial was instructed to report as many letters as

possible (Martial 1, filled squares); and when he was

instructed to report the most easily perceived letters first

(Martial 2, filled circles).

Please cite this article in press as: Valdois S, et al., A visual prodyslexia, Cortex (2011), doi:10.1016/j.cortex.2011.05.011

profile, well captured by a quadratic function (accounting for

93% of variance), whereas CA controls exhibited no positional

effect [F(4,88)¼ 1.74, p¼ .149] on this task. Martial exhibited

a lower score than CA controls in position 1 [6 vs 8.82,

SD¼ 1.11; t(22)¼�2.48; p¼ .011] but a ceiling performance in

positions P3 and P4. His report of letters in third and fourth

position was significantly higher than his report of the two

initial letters, in contrast to CA controls [�.18 vs .03; t(22)¼�1.93; p¼ .033]. His serial position function is also atypical with

regard to beginning readers since only three RA controls

showed a similar quadratic pattern of performance and none

of them showed lowest performance in initial position. In line

with the left imbalance observed with respect to CA controls,

his performance in position P4 was significantly higher as

compared to RA children (10 vs 5.96, SD¼ 2.15, t(25)¼ 1.84,

p¼ .039).

Martial shows an initial letter advantage (left-side bias) in

whole report but higher accuracy at identifying those letters

on and at the right of fixation (right-side bias) in partial report.

Such finding of quite different patterns in whole and partial

report is rather unusual, even in dyslexic individuals. More-

over, reporting the initial letter first in whole report was

obviously effortful for Martial and might have resulted from

top-down control. To assess his sensitivity to task instructions

and potential involvement of endogeneous control of atten-

tion, Martial was administered thewhole report task again but

with new instructions. He was then explicitly asked to report

first those of the letters he could more easily perceive. Using

the new instructions, Martial accurately reported 60 letters

out of 100, still performing lower than CA controls [t(25)¼�1.89, p¼ .035] but within the range of RA controls [t(25)¼1.57, p¼ 07]. However, his profile significantly differed from

that of both CA and RA controls (Fig. 3b). It was characterized

by a cubic function (S-shape) contrasting with the linear

function typically accounting for performance in non-dyslexic

individuals. Letters in third and fourth position were reported

more accurately than the initial letters, a pattern that differs

significantly from that of both CA [�.41 vs .16, t(24)¼�5.8;

p< .0001] and RA [�.41 vs .47, t(24)¼�3.0; p¼ .003] matched

children. Performance was not affected by variations in

instructions in the control participants. However, control

children did not fully understand the new instructions so that

results have to be interpreted with caution.

4.2.2. Control visual tasks

4.2.2.1. SEQUENTIAL REPORT. As in global report, the sequential

report task requires reporting asmany letters as possible from

a series of 5 consonants thus involving similar letter naming

and verbal short-term memory processes. However and

contrary to the global report condition, letters were here dis-

played in turn, one at a time, instead of simultaneously. Poor

performance was therefore expected in both sequential and

global report following a verbal short-term memory dysfunc-

tion while sequential report should be preserved following

a (simultaneous processing) VA span disorder.

Procedure: A central fixation point was presented for

1000 msec followed by a blank screen for 50 msec. Then,

5 letters were successively displayed one at a time at the

centre of the screen for 200 msec (ISI¼ 0) each. At the end of

cessing but no phonological disorder in a child with mixed

3 Note that Martial accurately read only 62.5% 3-letter wordsalthough all three letters were always accurately identified withinwords. Good letter identification but poor reading typicallyresulted from the addition of some letters or letter order errors asshown in the Appendix.

c o r t e x x x x ( 2 0 1 1 ) 1e2 2 11

each trial, the participant was asked to report as many letters

as possiblewithout any order or time constraints. Ten training

trials were proposed at the beginning of the task, for which

participants received feedback. No feedback was given during

the 20 experimental trials. The dependent measure was the

number of letters accurately reported (identity not location)

across the 20 trials (maximal score¼ 100).

Results: Martial accurately reported 67/100 letters, a score

well within the range of CA-matched control children

[t(25)¼ .07, p¼ .47]. His serial position function was charac-

terized by an initial-position advantage (primacy effect) fol-

lowed by a drop and finally an increase of performance in the

last position (recency effect). His pattern of performance was

similar to that of CA controls and well in accordance with the

response shape which characterizes verbal short-term

memory tasks.

4.2.2.2. INDIVIDUAL LETTER IDENTIFICATION. Method: Each of the 10

letters used in the letter-report task was randomly presented

(5 times each) at the centre of the screen, at 5 different

presentation durations (33 msec, 50 msec, 67 msec, 84 msec

and 101 msec). The letters had the same physical character-

istics as in the letter-string report tasks. Each trial began with

a central fixation point which was presented for 1000 msec,

followed by a letter. At the offset of the letter, a mask (13 mm

high, 37 mm wide) was displayed for 150 msec. The test trials

were preceded by 10 practice trials (2 for each presentation

time) using other letters and for which participants received

feedback. Participants were asked to name each letter

immediately after its presentation. The letter identification

threshold was estimated as the shorter presentation time

allowing at least 80% correct identification.

Results: Martial’s letter identification threshold was

reached at 67 msec, thus corresponding to themean threshold

of CA controls [t(25)¼ .31, p¼ .38] well below that of RA

controls.

4.3. Reading briefly presented words of different length

Stimuli: A list of 60 regular wordswas designed including 20 1-

syllable (3-to-4 letters), 20 2-syllable (5-to-6 letters) and 20 3-

syllable (8-to-9 letters) words. The three lists of different

length were matched in frequency (Log frequency was 3.88,

3.68 and 3.37 respectively, from BRULEX database, Content

et al., 1990). The words were displayed in lower-case letters

(font Geneva 24) in black on a white screen. A list of 30 words

(3� 10 words of each length) that differed from the experi-

mental words but had the same length served as practice

items.

Procedure: A fixation dot appeared in the middle of the

screen for 1 sec followed by a blank screen of 50 msec. A word

then appeared centred on the fixation point, which remained

on the screen for 200 msec. The word was then immediately

replaced (ISI¼ 0) by a backward mask which consisted of

a string of Xs of the same length as the word. The words of

each length were presented by blocks and the child was

informed about the length of the word that was to occur.

Martial was asked to read the word aloud or, if that was not

possible, to name all the letters he had identified. The mask

remained on the screen until the experimenter pressed a key

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that triggered the next trial. A short rest occurred after each

experimental block and the experimenter reminded the child

to maintain his gaze on the fixation point. Each list was

preceded by 10 practice words during which the child was

encouraged reporting as many letters as possible when the

word was not identified.

Results: Martial accurately read 60% 1-syllable words

(62.5% 3-letter words and 58.3% 4-letter words), 5% 2-syllable

words (12.5% 5-letter words and 0% 6-letter words) and none

of the longest words. His performance also showed a strong

length effect when considering the proportion of letters

accurately reported according to word length (see Fig. 4).3 This

strong length effect resulted from the fact that Martial re-

ported almost the same number of letters (around 3) whatever

the length of words. More precisely, 3.2 letters were reported

when attempting to read 1-syllable words, 3.0 and 3.2 for the

2- and 3-syllable words respectively.

In Fig. 4bed, data are plotted aligned at fixation location

which is indicated by the vertical line in the panels for 1-

syllable, 2-syllable and 3-syllable words separately. The right

half of the panels thus gives scores for letters that fell into the

right visual field and the left half gives scores for the letters

that fell into the left visual field. Inspection of Martial’s posi-

tion functions shows that his performance was at the top-

level for all positions on the shorter 3-letter words. Perfor-

mance slightly decreased for 4-letter words and a last position

disadvantage occurred. In contrast, a strong right-side

advantage clearly characterized performance on 5- and 6-

letter words. A slight left-side advantage was again observed

in 3-syllable words of 8 letters whereas a strong advantage for

the central letter and dramatic drop of performance in all the

other positions was found on the longest 9-letter words.

Overall, the number of letters accurately identified was

balanced between the left and right visual field (58/142 vs 59/

141). Interestingly, the peak of identification decreased with

length from 100% accurate identification at the preferred

position in 3e4-letter words, to 87% and 75% in 5- and 6-letter

words and 58% in 8-letter words. This decrease suggests that

letter identification capacity decreases sharply with word

length. For 9-letter words however, the peak increased

abruptly (87%) but then only allowed identification of the

letter located on the fixation point, as if position on the fixa-

tion point attracted all attention capacity to the detriment of

all the other positions in the string. CA-matched normal

readers made virtually no error (3.2%) whatever word length

when asked to name words presented for 200 msec.

4.4. Summary

Search for associated cognitive disorders revealed the absence

of oral language or verbal short-term memory impairment in

Martial. Assessment further showed that his phoneme

awareness skills were at the level of CA children but higher

than for RA controls, still against a delay hypothesis. Martial

cessing but no phonological disorder in a child with mixed

a b

c d

Fig. 4 e Length and positional effects when reading briefly presented words. (a) Probability of correct report of letters

according to word length. Probability of correct report of letters according to their position in words of 3 and 4 letters (b), 5

and 6 letters (c) and 8 and 9 letters (d). Each panel plots letter identification scores aligned at fixation (P0). In each panel, the

circles depict performance on the shorter items, the squares on the longer ones.

c o r t e x x x x ( 2 0 1 1 ) 1e2 212

however exhibited difficulties in phoneme fluency and per-

formed on this task as younger children of the same reading

level.

Martial’s good performance in the control tasks of single

letter identification and sequential processing of letter strings

further shows the absence of a general visual processing

disorder. His ability to identify individual letters presented for

only 67 msec shows preserved visual processing speed of

individual letters. His good performance in sequential report

suggests that he was able not only to retrieve letter names

very quickly during processing but also to maintain them in

verbal short-term memory for later report. His overall level of

performance on this task and the typical serial position

function we observed suggest preserved verbal short-term

abilities in Martial.

Investigation of Martial’s VA span abilities did not provide

as straightforward results as a priori expected. His perfor-

mance was clearly atypical in global report where he reported

fewer letters than CA controls and could only identify letters

in the initial position and on the fixation point (P1 and P3) at

the level of the controls. His performance profile was char-

acterized by a linear trend as in CA controls but performance

dropped more sharply across letters in the string, thus

resulting in a larger left-side advantage. However, his overall

performance in partial report did not differ from that of CA

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controls. He nevertheless exhibited an atypical pattern of

performance with better identification of those letters on and

at the right of the central fixation point but lower than ex-

pected identification of the initial letter. His profile in partial

report was thus characterized by a right-side advantage in

contrast to the initial (left-side) advantage observed in global

report.

Because Martial seemed to make an effort for attending to

the initial position in global report and because an initial-

position advantage might have reflected an endogeneous top-

down attentional control, the global report task was proposed

again butwith the explicit instruction to report themost easily

perceived letters first. With these new instructions, a right

attentional bias was observed and a serial position function

very similar to that previously described in partial report. A

difficulty to extract visual information from briefly presented

words was further found in Martial, thus resulting in a strong

length effect.

Overall, neuropsychological investigation revealed that

Martial had severe reading/spelling difficulties in the absence

of phonological and verbal short-term memory problems.

Despite good letter identification skills, he showed poor letter-

string processing inwhole report and an atypical performance

pattern in both whole and partial report. His tendency to

report only a few and similar number of letters from briefly

cessing but no phonological disorder in a child with mixed

c o r t e x x x x ( 2 0 1 1 ) 1e2 2 13

presented words varying in length further supports a visual

processing disorder.

5. Reaching movements

The following assessment investigated how Martial planned

and controlled sequential reachingmovements which involve

VA and simultaneous processing. A control task of cyclical

reachingmovements was further proposed. Timing of cyclical

reaching movements depends on movement amplitude and

size of the targets to be reached (Fitts, 1954). More precisely,

movement time (MT ) is function of a difficulty index

measured by the ratio between movement amplitude (A) and

target size (W ): MT¼ aþ b log2 (2A/W) with a and b depending

on the experimental conditions. Recently, Bourgeois and Hay

(2003) demonstrated that cyclical reaching movements

conform to the Fitts’ law from the age of five. Consequently, if

Martial had no motor disorder his performance was expected

to conform to the Fitts’s law for the production of cyclical

reaching movements.

5.1. Sequential reaching movement

In this task, Martial’s results were compared to those of two

groups of 15 RA and 15 CA-matched control children (CA:

mean¼ 10 years 8months, SD¼ 6months; RA: mean¼ 6 years

2months, SD¼ 6 months).

Method: Martial and the control children had to execute

a motor sequence composed of two successive reaching

movements on a digitizer (cf. Fig. 5). The first movement was

carried out in the sagittal plane towards a first target (T1)

placed at 15 cm from the starting position. The second

movement was directed from left to right in the transversal

plane, towards a second target (T2) placed at 10 cm from T1.

The size of T1 remained constant (.8 cm in diameter) whereas

the size of T2 was either .5 or 2 cm in diameter (see Fig. 5a).

a

500

600

700

800

900

1000

1100

1200

1300

Large target Small target

Mov

emen

t

MartialCA controlRA control

b

(ms)

time

Fig. 5 e Sequence of pointing movements. (a) Templates of

the sequence of pointing movements; movement goes

from the rest position (open square) to the first target T1

(top open circle) and from T1 to the second target T2 (right

open circle). The size of T2 can be either large (left panel

top) or small (left panel bottom). (b) Movement times of the

first pointing movement of the sequence (from the rest

position to T1) as a function of T2 size, for Martial and the

control participants.

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The participants had to perform each motor sequence thir-

teen times.

Results: Fig. 5b shows movement times for the first

reaching movement according to the second target size for

Martial as compared to the control groups.

In line with previously reported data (Louis-Dam et al.,

2000), movement time of the first reaching movement

increasedwhen the size of T2 decreased in both the CA and RA

controls (CA: mean¼ 678 msec� 118 and 627 msec� 150 for

the small and large T2 respectively; F(1,14)¼ 5.60,

MSE¼ 3499.11, p¼ .033; RA: mean¼ 1269 msec� 299 and

1064 msec� 228 for the small and large T2 respectively;

F(14)¼ 8.29, MSE¼ 38098.20, p¼ .012). Moreover whatever the

control group and for each child, no pause was observed after

the first target T1 had been reached. The motor system thus

anticipated the production of the second movement during

the execution of the first in both the CA and RA control groups.

By contrast, no significantdifference in reachingmovement

time was found in Martial whatever T2 size (mean movement

time¼ 1011� 144 msec and 893� 214 msec for the large and

small T2 respectively; F(1,7)¼ 3.17, MSE¼ 17707.62, p¼ .11).

Martial’s performance therefore demonstrates no motor

anticipation. Moreover, mean movement time was slower in

Martial than in the CA control group (Martial: 952� 187 msec,

CA controls: mean (SD)¼ 653� 134 msec; t(44)¼ 5.82,

p¼ .00000016) and faster than in the RA control group (Martial:

952� 187 msec; RA controls: mean (SD)¼ 1167� 277 msec;

t(44)¼ 3.16; p¼ .003). Also and in contrast to control children,

80%ofMartial’s velocity profileswere characterized by a pause

between the two targetmovements. Theduration of this pause

ranged from 89 msec to 241 msec. Despite this atypical

performance, timing of the second reaching movement nor-

mally fitted the Fitts law. Movement time decreased when

target size increased in Martial (Large: 1064� 134 msec; small:

1357� 253 msec; F(1,7)¼ 8.92, MSE¼ 38384.95; p¼ .02) as in

both the CA (Large: 650� 228 msec; small: 981� 267 msec;

F(1,14)¼ 108.85, MSE¼ 7545, p¼ .000000005) and RA control

children (Large: 1117� 252 msec; small: 1993� 409 msec;

F(1,14)¼ 59.88, MSE¼ 96282, p¼ .000056).

5.2. Control task: cyclical reaching movements

Method: Martial had to produce cyclical reaching movements

between two targets on a digitizer (Fig. 6). The size of the

targets remained constant (.8 cm in diameter) but the distance

between the two targets varied from 2 to 24 cm (ten distances

were chosen randomly). For each distance, Martial was asked

to carry out 10 go and backmovements as fast and as precisely

as possible.

Following Bourgeois and Hay (2003), we calculated for each

distance the linear regression between the index of difficulty

(ID) e In Fitts’ law ID¼ log2 (2A/W) where A is the amplitude of

the movement defined as the distance between the two

targets and W the width of the target e and the mean move-

ment time of a cycle (go and back movement) (see Fig. 6).

Lastly, the reciprocal of the regression slope (1/b) was calcu-

lated as an index of motor capacity in order to compare

Martial’s results with those reported by Bourgeois and Hay

(2003).

cessing but no phonological disorder in a child with mixed

0

.5

1

1.5

2

2.5

3Martial11 ans9 ans7 ans

Mov

emen

t tim

e (s

)

0.51

1.52

2.5

0 1 2 3 4 5 6 7 8Index of difficulty (in bits)

Mov

emen

t tim

e (s

)

TM=a + b * ID

a

b

c

Fig. 6 e Cyclical pointing movement. (a) Cyclical movement template: back and forth movements from T1 (bottom left circle)

to T2 (top right circle). (b) Martial’s movement time as a function of the index of difficulty [ID¼ Log2 (2A/W)]: linear regression

and correlation. (c) Comparison of Martial’s performance with CA and RA controls.

c o r t e x x x x ( 2 0 1 1 ) 1e2 214

Results: As shown on Fig. 6, Martial’s results revealed

a significant linear correlation (r¼ .96) between movement

time and the difficulty index. In addition, his index of motor

capacity (1/.45¼ 2.24) was between those reported for 9-year-

old (Mc¼ 2.02) and 11-year-old (2.73) children in the Bourgeois

& Hay’s experiment and much higher than for 7-year-old

children (Mc¼ 1.68). Therefore, Martial’s performance in

cyclical reaching movements did not significantly differ from

that of non-dyslexic children of the same CA.

Overall, both Martial’s ability to perform cyclical reaching

movements and the adapted timing of his second movement

in the sequential reaching task are evidence against general

motor difficulty. In contrast, Martial demonstrates specific

difficulties in the programming of motor sequences. Contrary

to control children, no motor anticipation was observed in

sequential reaching movements: duration of the first motor

component of the sequence was not influenced by the char-

acteristics of the second movement target. Moreover very

atypically, pauses occurred between the two target move-

ments. These results strongly suggest that Martial processed

the two components of the sequence not as awhole but as two

independent motor units as expected if the two targets had

not been simultaneously processed.

6. General discussion

6.1. A form of peripheral dyslexia

In this study, we reported the case ofMartial, a young boywith

a severe reading and spelling acquisition disorder. Martial

exhibits severe mixed dyslexia e as evidenced by his major

difficulties in reading regular and irregular words and pseudo-

words e and a surface dysgraphia characterized by poor word

spelling but relatively preserved pseudo-word spelling

performance. An analysis of his errors revealed a high

proportion of visual errors in reading but no phonological

errors in either reading or spelling. Poor decoding of both

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words (regular and irregular) and pseudo-words and the

predominance of visual errors on all types of items suggest

a deficit in the early stage of orthographic visual analysis

characteristic of peripheral dyslexia. Different subtypes of

peripheral dyslexia have already been reported in children, as

attentional dyslexia (Friedmann et al., 2010), letter position

dyslexia (Friedmann and Rahamim, 2007), neglect dyslexia

(Friedmann and Naachman-Katz, 2004) and visual dyslexia

(Valdois et al., 1995). Attentional dyslexia is a reading deficit in

which letters migrate between neighbouring words but are

correctly identified. Obviously, Martial’s reading errors typi-

cally follow from problems in the decoding of letter identity at

the word level, in sharp contrast with the attentional dyslexia

profile. His reading profile also differs from that of letter

position dyslexia since his ability to encode the relative posi-

tion of letters within words was relatively preserved, with the

production of only a few letter-order encoding errors. Neglect

dyslexia often affects identification of letters in the left side of

words and a left mini-neglect was indeed reported in dyslexic

children (Facoetti et al., 2001; Hari and Renvall, 2001).

However, Martial does not demonstrate any clear disadvan-

tage for the left or right visual hemi-fields. No sign of neglect

was observed in tasks of target cancellation among dis-

tracters, picture or word copying. Further evidence against

neglect dyslexia comes from the analysis of errors when

reading briefly presented words. In this task, Martial’s letter

identification rate was similar for letters displayed in the right

and left hemi-field. However, some attentional imbalance,

which punctually affected either the right or left hemi-field,

was observed in this task as in the letter-report tasks. Rele-

vance of this VA problem in the explanation of Martial’s

reading difficulties will be discussed below.

Lastly, a high proportion of Martial’s reading errors were

visual, as previously described in developmental visual

dyslexia (Valdois et al., 1995). However, previously reported

cases of visual dyslexia showed a tendency for reporting the

target word as another visually similar andmore frequent real

word. To the contrary, Martial’s visual errors typically resulted

cessing but no phonological disorder in a child with mixed

c o r t e x x x x ( 2 0 1 1 ) 1e2 2 15

from laborious attempts to decode the target word and only

occasionally yielded the production of another real word.

However, many errors in Martial could be interpreted as

resulting from a letter-identity encoding problem, as in visual

dyslexia. The potential origin of these visual errors will be

discussed below after discussion of Martial’s phonological

abilities.

6.2. Good phonological and verbal short-term memoryabilities

It is widely assumed that phonological deficits cause the

reading difficulties observed in most individuals with devel-

opmental dyslexia (Vellutino et al., 2004). Such phonological

disorder has been described as resulting in poor phoneme

awareness, poor lexical retrieval and poor verbal short-term

memory. Martial was thus engaged in a series of tasks

designed to assess these three phonological dimensions.

Martial demonstrated very good phoneme awareness

skills, which contrasted with his very low reading level. Such

a discrepancy between phoneme awareness and reading

acquisition is rather surprising assuming that there is

a reciprocal causal relationship between phonological

awareness and reading achievement and that phoneme

awareness in part develops as a consequence of literacy

exposure (cf. Castles and Coltheart, 2004, for a review). Neu-

ropsychological investigation of Martial’s oral language skills

revealed the absence of picture naming difficulties, thus

suggesting activation of preserved phonological information

in long-term memory. His accurate performance in the

sequential report of series of visual letters rapidly displayed in

turn further suggests normal (rapid) activation of letter

names, against the hypothesis of slow lexical retrieval abili-

ties. Finally,Martial demonstrates no evidence of verbal short-

term memory problems. He was able to report as many digit

names as the controls in both the forward and backward digit

span. His performance was very high in pseudo-word repeti-

tion even when the task involved long pseudo-words whose

syllables had to be accurately decoded and maintained in

short-term memory for their subsequent report. Still in

support of his good verbal short-term memory skills, Martial

performed the phoneme awareness tasks as normal readers

do and even succeeded in those tasks (as spoonerisms) that

load most heavily on working memory. Also, the sequential

letter-report task e which was particularly demanding in

terms of lexical activation and verbal short-term memory e

was performed within the normal range against the hypoth-

esis of a phonological or verbal short-term memory problem.

Overall, evidence for normal activation of phonological

information in long-term memory, good phoneme awareness

and good verbal short-term memory is strong argument for

preserved phonological skills in Martial, well in agreement

with the report of a harmonious development of his oral

language skills in early childhood.

Further evidence for good phonological skills comes from

the inspection of Martial’s reading and spelling errors. He

produced a high rate of phonologically motivated errors in

both reading (regularisation errors) and spelling (phonologi-

cally plausible errors), thus demonstrating he had good

knowledge of letter-sound correspondences (in reading),

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could accurately sound out heard words into phonemes and

could translate each target phoneme into a plausible

grapheme (in spelling). Thus, Martial is a case of develop-

mental dyslexia that is clearly not phonological.

Martial’s good phonological abilities sharply contrast with

his very poor performance in pseudo-word reading. There are

only a few reports of cases of acquired dyslexia which have

difficulties in pseudo-word reading but nevertheless exhibit

good phonological processing skills (Tree and Kay, 2006). Also,

some developmental cases have been reported with a profile

of surface dyslexia but slow pseudo-word reading in the

context of preserved phonological abilities (Castles and

Coltheart, 1996; Valdois et al., 2003). Martial provides further

evidence that impairments in reading pseudo-words are not

always matched by deficits in phoneme awareness and

phonological processing.

6.3. A visual processing deficit

In a second step, the hypothesis of an associated VA deficit

was evaluated taking into account recent findings suggesting

that a VA span disorder might contribute to the poor reading

outcome of dyslexic children independently of their phono-

logical skills (Valdois et al., 2003, 2004; Bosse et al., 2007; see

Bosse and Valdois, 2009, for similar findings on a large sample

of typically developing children). Martial’s VA span was thus

evaluated through two whole and partial report tasks

assessing parallel processing of letter strings. Because they

require the processing of unpronounceable strings of conso-

nants, the report tasks are not sensitive to any of the

psycholinguistic dimensions typically involved in reading

such as graphemeephoneme mapping, phoneme blending or

lexical knowledge. Accordingly, children with phonological

dyslexia show good performance on the letter-report tasks

despite their poor graphemeephoneme mapping, poor verbal

short-term memory and poor phoneme awareness skills

(Lallier et al., 2010; Valdois et al., 2003).

As expected following a VA span disorder, Martial

demonstrated poor performance in the whole report para-

digm. His position patternwas quite similar to that reported in

Nicolas (Valdois et al., 2003) who otherwise demonstrated

a similar reduction in the number of reported letters and

similar position patterns in whole and partial report.

However, Martial’s letter-report performance was not signifi-

cantly impaired in partial report, so that the hypothesis of

a visual short-term memory disorder cannot be a priori dis-

missed as a potential cause of his selectively poor perfor-

mance in whole report. Further, his whole report position

pattern was characterized by a sharp left-to-right drop of

performance, still compatible with an abnormal decline of

information in visual short-term memory. Nevertheless,

a visual short-term memory interpretation cannot straight-

forwardly account for the right-side bias Martial exhibited in

both partial report and the whole report paradigm with the

new instructions.

It is typically assumed that the number of encoded objects

in visual short-term memory depends on the object discrim-

inability, on the amount of allocated attention and on visual

short-term memory capacity (Habekost & Starrfelt, 2009). In

partial report, a cue is presented at the offset of the letter

cessing but no phonological disorder in a child with mixed

c o r t e x x x x ( 2 0 1 1 ) 1e2 216

string, which indicates the position of the target to be re-

ported. Each letter position has the same probability of being

chosen as target and a single letter, the cued one, has to be

stored in visual short-term memory for subsequent report. At

the cue onset, attention is directed towards the target letter

whose identification depends on its discriminability and on

the way attention was initially distributed across the letters in

the string. Proficient readers matched for CA with Martial

were able to accurately identify single letters when presented

for only 67 msec and showed no positional effect in partial

report. These results reflect good letter discriminability and

equal attentional weighting on letters across positions. In

partial report, Martial’s performance is characterized by

a quadratic function showing that probability for letters to be

accurately identified varies as a function of their position in

the string. This atypical pattern of performance cannot follow

from a discriminability problem. First, Martial could identify

individual letters with the same efficiency (at 67 msec) as

proficient readers; second, the target letters had the same

probability to occur in each position of the string so that

a discriminability disorder would have resulted in a low

performance but no positional effect. As a consequence,

Martial’s positional function in partial report suggests an

initial attentional imbalance with stronger attentional

weights allocated on and at the right of the fixation point but

reduced attentional weights on the initial position of the letter

string.

The global report condition requires as many letters as

possible to be accurately reported. Following Bundesen (1990),

we assume that letters in strings compete for access to

a visual short-term memory with limited storage capacities.

Additional attentional weights are thus allocated to each

letter. The attended letter activation increases up to the letter

identification threshold so that it can be recognised, enters

verbal short-term memory and becomes available for later

report. Proficient readers matched for CA with Martial show

a slight left-to-right gradient in global report suggesting a left

attentional bias favouring the string initial position. This

visual field asymmetry might be accounted for by automatic

processing related to reading habits or might result from an

endogeneous top-down attentional control.

Martial’s performance in global report shows the same

initial-position advantage as in normal readers but a sharper

drop of performance across positions, so that much fewer

letters could be reported across trials. However, this first

position advantage vanishes when instructions are changed

suggesting that shifting of attention towards the initial posi-

tion was under endogeneous top-down control. In the “new

instruction” global letter-report task as in partial report,

Martial’s attentionwas automatically allocated on the fixation

point and at the right of fixation to the detriment of the first

position where letters were only very poorly identified.

Accordingly, the same initial attentional imbalance (right-side

bias) as observed in partial report seems to characterize

Martial’s whole report performance when top-down control is

discouraged. Such abnormal allocation of attention during the

early stage of processing could limit the number of letters

accurately identified and encoded in visual short-term

memory. Nevertheless, an additional limitation of visual

short-term memory storage capacity cannot be set aside on

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the basis of the current data. Previous findings have indeed

shown that some children with a VA span disorder do exhibit

a visual short-term memory capacity reduction even if both

disorders were not systematically associated (Dubois et al.,

2010).

It is further worth considering that Martial’s performance

is very similar to that of younger children of the same reading

level in whole report and only tends to differ in partial report.

Although such similar performance inMartial and RA controls

might be viewed as a consequence of their reading level, some

findings rather suggest that similar letter-report performance

in Martial and younger readers might have different causes.

Indeed, poor performance of the very beginning readersmight

partly relate to their poor individual letter processing abilities.

Indeed, RA matched controls required 95 msec exposure

duration to accurately identify individual letters while Martial

like CA-matched controls reached the same identification

level at 67 msec. Poor individual letter discriminability might

also account for the poor performance of RA controls in global

report. The similar performance of Martial on this task cannot

be interpreted the same way given his above RA-controls’

individual letter processing skills.

6.4. Length effect and the VA span

A normally developing reading system manifests itself in the

early ability of the reader to attend to all letters of the word in

parallel. At all grades, parallel processing is optimized when

the child fixates the centre or slightly left of centre within the

word sequence (Aghababian and Nazir, 2000). Accordingly, CA

controls virtually showed no differences in identification

accuracy between shorter and longer words when they were

fixating the centre of the word during 200 msec. Contrary to

proficient readers and as expected following a VA span

disorder, the performance ofMartial was significantly affected

by word length and only a few and similar number of letters

from the target words were identified whatever their length.

The ability of normally developing children to attend to all

letters of the wordmust in part bemonitored by their growing

knowledge about orthography while the absence of extended

lexical knowledge in very beginning readers probably

contributes to the strong length effect they demonstrate in

word reading (Nazir and Huckauf, 2006; further see Dubois

et al., 2007). However, differences in lexical knowledge

cannot by themselves account for the low performance of

Martial since he exhibits similar letter identification problems

and atypical position patterns in global and partial report

although performance on these tasks does not trigger lexical

knowledge.

Assuming that letter-string processing relies on capacity-

limited attention processing, then the distribution of atten-

tion across longer strings would result in decreased attention

weights on each letter in the string. Decrease of the identifi-

cation peak with length in Martial suggests that his ability to

identify even the most prominent letter (under the focus of

attention) decreases with length. This suggests that the total

amount of attention shared out among the different letters in

the string might be abnormally reduced in Martial thus

resulting in enhanced confusability between visually similar

letters and increased letter identification problems. A

cessing but no phonological disorder in a child with mixed

c o r t e x x x x ( 2 0 1 1 ) 1e2 2 17

reduction of the visual processing capacity has been recently

advocated as a potential source of developmental dyslexia

(Dubois et al., 2010) and was also reported as potentially

explicative of impaired simultaneous perception in simulta-

gnosia (Duncan et al., 2003) and neglect (Duncan et al., 1999).

Thus, different forms of acquired and developmental periph-

eral dyslexia might share a visual processing capacity

disorder.

6.5. Is the VA span disorder specific to verbal material?

The VA span has been assessed inMartial through letter-report

tasks so that the disorder might have been specific to letter-

string processing (Ziegler et al., 2010; however Lobier et al.,

submitted for publication). Otherwise, reading is a recent

cultural invention in the humankind history so that learning to

read probably developed through the specialisation of pre-

existing visual abilities. The simultaneous visual processing

disorder Martial exhibits in letter-string processing was thus

expected to impact non-linguistic abilities aswell, as far as they

involve visual simultaneous processing. Martial was thus

engaged in a sequential reaching task that required simulta-

neous processing of two to-be-reached visual targets. Whereas

both CA and RA controls exhibited motor anticipation during

the execution of the first movement target, Martial showed no

sign ofmotor anticipation but rather executed the sequences of

reaching movements as a succession of two independent

movements instead of integrating information on the whole

sequence for motor action. Results further revealed that

Martial’s performance in a simple motor task of cyclical reach-

ing conformed to themotor principles (i.e., Fitt’s law) identified

in non-dyslexic children. These findings are evidence for the

absence of spatio-temporal regulation difficulties inmovement

execution as far as a single target has to be taken into account.

They suggest that Martial does not suffer from a general motor

disorder but does exhibit a specific difficulty in the early part of

movement sequence programming.

Interestingly, sequential movement planning has been

described as involving attention deployment (Deubel et al.,

1998; Deubel and Schneider, 2004). When a sequence of two

goal-directed movements is programmed, characteristics of

the second target are already processed before the onset of the

movement to the first target (corresponding to motor antici-

pation). For this purpose, VA has to be allocated not only to the

first but also to the second movement target, thus providing

spatial information for action. Previous findings further

suggest that all movement relevant locations are selected in

parallel during movement preparation (Baldauf et al., 2006).

Martial’s inability to integrate information from the second

target during planning of the first sequence of movement

suggests that he might suffer similar simultaneous visual

processing disorder in both sequential reaching movements

and letter-string processing.

Although it would be premature to conclude that the VA

spandisorderextends tonon-verbalmaterial onthebasisof this

sole evidence, the current findings are well in agreement with

previous report that a visual processing capacity deficit is not

restricted to letter processing but also affects figure identifica-

tion (Finke et al., 2007) and non-alphabetic characters catego-

rization (Lobier et al., submitted for publication). Moreover,

Please cite this article in press as: Valdois S, et al., A visual prodyslexia, Cortex (2011), doi:10.1016/j.cortex.2011.05.011

neurobiological investigation of proficient readers showed that

the global report task elicits strong activations within the pari-

etal regions, involving in particular the superior parietal lobules

bilaterally and the left posterior parietal regions (in adults:

Peyrin et al., 2008; Valdois et al., 2009; in children: Peyrin et al.,

2011). These parietal regions are under-activated in dyslexic

individuals with a VA span disorder (Peyrin et al., 2008, 2011),

thus providing further evidence for the importance of parietal

regions in normal reading and developmental dyslexia. Inter-

estingly enough, the posterior parietal cortex is further known

to be involved in the planning and control ofmovement (Buneo

and Andersen, 2006). The left posterior parietal cortex is in

particular involved in the updating of sensorimotor represen-

tations prior to movement execution (Khan et al., 2005;

Medendorp et al., 2003, 2005; Rushworth and Taylor, 2006).

The posterior parietal regions previously described as involved

in letter-string processing also contribute to visually guided

movements (Perenin and Vighetto, 1988; Culham et al., 2006)

and reaching movements to targets presented in peripheral

vision (Prado et al., 2005). Saccades, attention and reaching

jointly activate the superior parietal lobule (Simon et al., 2004).

The overall data are thus compatible with the hypothesis that

a parietal dysfunction leading to poor VA span abilities might

further result in poor reaching performance.

7. Conclusion

Notwithstanding the importance of phonological abilities in

reading acquisition and the relationship between phonological

disorders and developmental dyslexia, the current case study

provides clear evidence that a severe reading/spelling disorder

can occur in the child despite good oral language, good

phonemeawarenessandgoodverbal short-termmemoryskills.

Martial rather suffers a visual processing disorder that impacts

parallel letter-string processing while leaving single letter

identification skills preserved.Martial’s reduced letter encoding

abilities and atypical allocation of attention in letter-string

processing would prevent orthographic knowledge acquisition

thus resulting in poor irregular word reading and a severe

spelling disorder. However, difficulties in orthographic extrac-

tionwould furtherbedetrimental for thedecodingofnewwords

thus resulting in poor pseudo-word reading despite good

phonological abilities. Overall, the current findings put visual

processing back in the front row as a potential source of some

forms of mixed developmental dyslexia.

Acknowledgements

We thank Brenda Rapp and Naama Friedman for their helpful

comments on a previous draft of the paper. We are grateful to

Estelle Gillet-Perret for her help in collecting the data. We are

indebted to both Martial and his parents for having partici-

pated with enthusiasm to this research. This work was sup-

ported by grants from the ANR (Research National Agency,

Programme Blanc “VASRA” no.: 07-BLAN-0019-01) and the

“Region Rhone-Alpes” (Cluster 11 “Handicap, Vieillissement,

Neurosciences”).

cessing but no phonological disorder in a child with mixed

c o r t e x x x x ( 2 0 1 1 ) 1e2 218

Appendix

(1) Martial erroneous responses when reading HF and LF regular words and irregular words. Asterisk[ regularized items.Underlined responses[ another Frenchwords. Capitals indicate a plausible pronunciation for the target letter but withoutconsideration of the context.

Reading HF regular words Martial response Reading HF irregular words Martial response

Faute þ femme* fame, feme

Nuit þ hier þVague vagu ville þMontagne þ monsieur* mon-si-eur

Soin þ sept* seute

Soif þ aout* a-ou-te

Mal þ dix þSauvage sauvaG seconde* seconde

Mission þ million þFuite þ fusil fusui

Elan elor echo* e-cho

Anime amine tronc* tronk

Talon talo tabac tablas

Splendeur e orchestre fourchette

Maman þ moyen* moyan

Pardon parbon parfum* parfume

Caravelle Sarvelle cacahuete* Saca-u-e-te

Electron ecole equateur equaten

Jaloux jalon gentil Gentile

envoye þ examen excellent

Reading LF regular words Martial response Reading LF irregular words Martial response

sac sa net* ne

conge congu galop* galope

dorade bora dolmen* dolman

rigueur riguen respect* respecte

asile aSile bourg* bourge

approche þ aiguille* aiguile

piege þ poele* po-e-le

bottine bottin bapteme batene

hausse hasse oignon oiguon

astronome þ aquarelle aquerelle

alchimie aclinie orchidee* or-chi-dee

avanie ava agenda agrande

courroie croie compteur* competeur

baril bain stand* stan

cargo þ toast* toa

esquif esqinf escroc escoc

cric cri cake* ca-ke

cagoule þ chorale* cho-ra-le

acrobate þ aquarium* akariume

bise biS paon pano

(2) Martial erroneous responses in pseudo-word reading. Capitals indicate a plausible pronunciation for the target letter butwithout consideration of the context.

Reading pseudo-words Martial response Reading pseudo-words Martial response

rac þ sande saude

gavin þ chon þcaldon Salbon givor Givo

rigende riGende bondeuse bondense

plour þ sule þvatriche þ toir þpisal piSal mic miS

bertale þ taubage tanbang

(continued on next page)

Please cite this article in press as: Valdois S, et al., A visual processing but no phonological disorder in a child with mixeddyslexia, Cortex (2011), doi:10.1016/j.cortex.2011.05.011

(continued )

Reading pseudo-words Martial response Reading pseudo-words Martial response

aivron a-i-vron mardion maribo

pacirande þ fudin fubi

anchovee auchovee esan eSan

agante agran trane tan

courlone courlon tagin taGi

stipe sip splindron spidon

torac torache modan þcasine Sasine tandir tanidr

bate date taparelle þcoginte þ abindeur abindeu

abranise arani gental Gental

glon golin ontage ontagle

(3) Spelling errors on consistent, inconsistent and exception words.

Spelling consistentwords

Martialresponse

Spelling inconsistentwords

Martialresponse

Spelling exceptionwords

Martialresponse

ordure ordur pain pin seconde segode

poisson poison garcon garson monsieur mesie

jardin gardin papier papie million milion

bille bill cirque sirce femme fam

chapeau chapo hiver iver ville vil

vigne vign bain bin fusil fusi

fete feit ocean oseen tabac taba

gare gar aussi ausi galop galau

verbe verdre terre ter aout out

couleur couler serpent serpen parfum parfin

(4) Pseudo-word spelling errors.

Spelling pseudo-words Martial response Spelling pseudo-words Martial response

gontra þ flocachin þcopage copag abranise abranis

bartin þ verdulin þdatoir þ abritel abriel

majon magon scropale þnagul þ tergilone tergilon

savette savet gordive þbracho þ siropage siropag

famir þ corabone coraboe

poulan þ pontaneur pontaner

(5) Martial’s errors when reading words presented for 200 msec.

Reading (200 msec)1-syllable words

Martialresponse

Reading 200 msec2-syllable words

Martialresponse

Reading 200 msec3-syllable words

Martialresponse

pas þ lundi bndi tabouret oni

ane þ bague ge boucherie ch

mur þ papier pio mercredi cir

fois þ oiseau a arbitre dia

roc cron epine epin decembre mob

gaz garz radio robio medecin din

haie hain crayon yo fabriquer ipn

nuit nuir repas pas monument uin

lion þ souris suis ecureuil euirl

(continued on next page)

c o r t e x x x x ( 2 0 1 1 ) 1e2 2 19

Please cite this article in press as: Valdois S, et al., A visual processing but no phonological disorder in a child with mixeddyslexia, Cortex (2011), doi:10.1016/j.cortex.2011.05.011

(continued )

Reading (200 msec)1-syllable words

Martialresponse

Reading 200 msec2-syllable words

Martialresponse

Reading 200 msec3-syllable words

Martialresponse

tres þ voyage voya escargot ain

eau eaut partir pais aviation aian

clou clon bateau eau pantalon tain

roi þ maman naon autrefois aiter

mare þ ballon lon signature ait

taux þ carton caoin spectacle spon

nez þ livre lire voisinage ina

bord þ voleur vleau casserole er

fete þ jardin jeain apprendre en

file þ index inde fenetre ener

banc da-u-e tresor fis elephant enf

c o r t e x x x x ( 2 0 1 1 ) 1e2 220

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cessing but no phonological disorder in a child with mixed