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Paying Attention to Consciousness

Rik Hine _____________________________________________________________ Abstract: I look at a series of well-known, blindsight experiments, which

conclude that attention occurs in the absence of awareness. Based on a widely

accepted neurophysiological model of attention, I argue that the experiments are

not as compelling as they initially appear. Indeed, there are good philosophical

grounds for thinking that the research results are, in fact, fully compatible with

the claim that attention is a minimally sufficient condition for consciousness. I

conclude by showing that this argument generalizes to cover other purported,

non-pathological cases of dissociation between attention and awareness.

1. Introduction

Although the last twenty years or so have seen the study of Consciousness

rise from a lowly cottage industry to the heady heights of scientific respectability,

it was a research subject over a century ago (e.g., James, 1890). Perhaps due to its

less salubrious scholarly status, much of the work was couched in terms of

‘awareness,’ and investigated its complicated connection(s) to attention. I would like to thank… Address for correspondence: Department of Philosophy, Texas Christian University. TCU Box 297250, Scharbauer 3015, 2850 South University Drive, Fort Worth, TX 76129-001 297250 | Sc3015 | 2850 South University Drive | Fort Worth, TX 76129-0001 | (817) 257-7370 Email: rik.hine@tcu.edu

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Unfortunately, before clarity, let alone consensus could be achieved, the

academic fission of Natural Philosophy into ‘Philosophy’ and ‘Psychology’

consigned the respective concepts (Consciousness and Attention) to different

disciplines, and for a while, at least, the ‘historical dustbin.’ 1 Indeed, it is only

lately that they have, once again, become parts of the same conversation. Yet

even in an era when we can be explicit about the elephant in the living room, its

commonly acknowledged connection with attention is just as confounding.

According to ‘commonsense’ (Mole, 2008), for instance, the ‘folk’ appear

to think that whilst we are aware of everything we pay attention to we are not

always paying attention to the things we are aware of. But, a body of

experimental evidence appears to undermine these claims. Mack and Rock (1998)

for instance, argue that attention is necessary for consciousness. That is, one can

only be aware2 of those things to which one is paying attention. Kentridge, et al.

(1999, 2004), on the other hand, argue that attention is not sufficient for

consciousness. In other words, one can attend to an object3 without being aware

of it.

So much, then, for common sense, and so much, it seems, for a solution to

this issue. Indeed, the only thing the interested parties agree upon is that where

1 At least this was the case in ‘Anglophone’ Philosophy. Behaviourism put paid to such studies within Psychology. 2 I will use ‘consciousness’ and ‘awareness’ (and their cognates) interchangeably, although it is important to note an ambiguity between a simple ‘detection’ sense, and an ‘experiential’ sense of ‘awareness.’ The former reading is meant to exclude the latter, but the latter reading includes the former. My use of ‘awareness’ throughout this work should be read in the latter sense unless I explicitly claim otherwise. 3 Similar arguments about attention can be made in relation to features, locations, etc. See Kentridge (2011) for a brief overview.

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consciousness is concerned, attention might be a tusk or a trunk but it is not the

whole elephant4.

On the face of it there are good grounds for considering consciousness and

attention to be distinct: neither appears to be a unitary phenomenon and there

are issues about potential connections between their respective ‘aspects.’ A brief,

and far from complete, count of the questions included under the aegis of

‘consciousness’ involve psychological issues contrasting ‘explicit’ and ‘implicit’

processing (Tulving, 1993), ontological issues about the ‘explanatory gap’ (see

Levine, 1983; Chalmers, 1996), and conceptual issues of ‘access’ versus

‘phenomenality’ (e.g., Block, 2005,)5.

The concept of ‘attention’ fares no better, with authors arguing about

‘early’ versus ‘late’ accounts of selective attention (e.g., Broadbent, 1958, Deutsch

and Deutsch, 1963), ‘overt’ and ‘covert’ orienting of attention (e.g., Posner, 1980),

related questions of ‘exogenous’ versus ‘endogenous’ attention (e.g., Corbetta

and Shulman, 2002), and associated concerns about spatial versus object

attention (e.g., Pylyshyn, 2006).

In the face of these complications, some philosophers have recently

focused on providing a univocal notion of attention.6 But even if we start by

assuming that we are on the same page, so to speak, the threat remains: defining

attention in terms of its phenomenology leaves us with a non-trivial question

about its functional role, whereas defining it in terms of functional role leaves us

4 Prinz (2007, 2010, 2011, 2012) provides a notable Philosophical exception to this trend. 5 Tsuchiya and Koch, (2008).

6 For recent attempts see, Dicey-Jennings (2012), Koralus (Forthcoming), and the essays in Mole, Smithies, and Wu, (2011).

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with a non-trivial question about its connection to consciousness (Smithies, 2011).

In accord with this concern, Kentridge (2011), claims that:

…purely philosophical approaches to this issue, based only on our

introspective grasp of the two phenomena, are prone to degenerate into

mere verbal disagreements between advocates of alternative stipulative

definitions7. In my view, we should therefore approach the relationships

between attention and consciousness empirically8. (P. 229)

Of course, if introspection were the only tool that philosophers could bring to the

table, then pursuing a purely empirical path would make methodological sense.

The antecedent of this claim, though, is obviously false and to insist on the

consequent brings to mind babies and bathwater.

In what follows, I focus on the nature of the relationship between

attention and consciousness9 by exploiting both psychological and philosophical

means. First, I look at a series of well-known experiments, involving a blindsight

subject, which conclude that attention is possible in the absence of awareness.

Then, based on a widely accepted model of attention, from the

neurophysiological literature, I argue that the experiments are not as compelling

as they initially appear. I follow this with a series of philosophical arguments for

thinking that the research results are, in fact, fully compatible with the claim that

7 Kentridge explicitly attributes this point to Smithies (2011).

8 Admittedly, Kentridge’s claim, here, is ambiguous between rejecting ‘purely philosophical approaches’ altogether and rejecting them ‘…based only on our introspective grasp of the two phenomena…’ (My emphasis) 9 I am specifically concerned with the relationship between visual attention and visual awareness.

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attention is a minimally sufficient condition for consciousness10. I conclude by

showing that this argument generalizes to cover other purported, non-

pathological cases of dissociation between attention and awareness11.

2. Varieties of attention and consciousness

As already noted, it’s unlikely that this complex issue is soluble solely

through psychological investigation. But it will be instructive, at least initially, to

investigate the connection between attention and consciousness on empirical

grounds. Indeed, it will serve to show the limiting effect of such a constrained

form of enquiry.

Any plausible empirical representation of the relation, then, requires an

unambiguous account of what each of the relevant phenomena amount to.

This is controversial, of course, but Kentridge helps us on our way with an

operational definition of consciousness:

One familiar proposal…is that a conscious state be defined as a state that is

available for explicit verbal report. There are plenty of problems with this

definition…But so long as we restrict our attention to normal humans,

10 I aim to make rational space for the possibility that attention and consciousness are coextensive. This claim, were it vindicated, would allow us an explanatory trade-up from a theory of attention to a theory of consciousness (Mole, 2008a). Nevertheless, the size of such a project outruns the scope of this paper. To minimize the gap, then, between aim and achievement, I limit my ambition, to the sufficiency claim. See my (2010), which focuses on the necessity condition of the coextension claim. 11 I offer an account of the difference between sufficient and ‘minimally’ sufficient conditions in § 6.1.

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without motor or language deficits, and with intact connections between

their cerebral hemispheres, this definition is…adequate for most cognitive

neuroscientific purposes. (Ibid. p. 230)

As for attention, any number of examples might suffice, but Desimone

and Duncan (1995) offer us a useful way in which to elaborate on our elusive

quarry. They use, as an example, a series of experiments in which subjects are

instructed, prior to the actual test, that they should report the target (black)

letters, and ignore the non-target (white) letters, in a cluttered visual array of

letters. The display is presented at a speed that eliminates the possibility of overt

attention; that is moving one’s eyes to foveate on the relevant targets. The point

of the experiment is to mimic our cluttered visual environment, in which only a

limited number of targets are relevant to our current behavior.

The purpose of outlining this experiment is to emphasize some widely

recognized aspects of attention; the first is that we possess a limited cognitive

capacity for processing visual information12; the second, related notion, is

selectivity – filtering out unwanted information to allow for heightened

processing of the behaviorally relevant kind; third, the notion of covert (as

opposed to overt) orienting of attention. Indeed, as Kentridge (2011) notes, this is

why providing an operational definition for attention is so difficult: it is hostage

to the number of ways in which the notion is used. Nonetheless, he notes that:

The core of attention…is the use of information to facilitate the execution of

a task to which many stimuli might potentially provide the solution. The

information that is used need not tell the subject anything about what the 12 Although see Mole (2011) for a dissenting position.

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solution to the task is. The use of that information is facilitative, not because

it primes the solution but because it excludes some irrelevant stimuli from

consideration. (Ibid. p.229)

Having these operational definitions in hand, however, is merely the first

stage in our investigation. Further questions abound when it is claimed that a

subject can attend to a target without awareness. For instance, is the subject

unaware of the meaning of the target, some of its properties, or the actual

existence of the target?13 Relatedly, and ideally, we would also want a

complete account both of the orienting and selectional capacity of attention.

But before we even attempt to confront these complexities, a brief

philosophical interlude is in order: we should ask, from a representational

point of view, what is it that we select from, so to speak, in the first instance?

3. Attention and Visual Representations

The prevailing attitude amongst philosophers is that the minimum

conditions for constructing a theory of consciousness include explaining both the

‘what’ and the ‘how,’ as it were (see Prinz, 2010). That is, what are we visually

conscious of and how do we become conscious of it? Put another way; where in

visual processing are we able to point, so to speak, to representational contenders

for consciousness, that is, those representations with qualitative character?

Second, how does awareness of these particular representations come about?

13 See Kentridge (2011) for more details, including issues involving awareness without attention.

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Now although the present project is specifically concerned with the latter of

these two issues, it will undoubtedly aid overall clarity to offer at least a sketch of

the first.

A worry related to the one that concerns us, here, is the distinction

between early vs. late accounts of selective attention: where, in the stream of

visual processing, does selection, for awareness, occur? This debate appeared to

be intractable, with leading researchers declaring that it would never be solved,

but a solution does, in fact, appear to be in sight14. Nonetheless, whatever one’s

position on this subject is, it is uncontroversial that we do not consciously

entertain all of the representations that we visually process; even under normal

visual conditions, we might well perceive objects without any awareness.

Indeed, Block (2009) concurs,

Some activations in the visual system are very weak, do not ‘prime’ other

judgements…and do not yield above chance performance on forced

choice identification or detection…On a very liberal use of the term

‘representation’ in which any neural activation that correlates with an

external property is a representation of it…one might nonetheless call

such activations representations…but it will be useful to be less liberal

here, describing…weak activations…as non-representational. However,

if activations…are strong enough to be harnessed in subjects’ choices (at

a minimum in priming), then we have genuine representations. (p. 1112)

So at what stage of processing does the visual system produce the

requisite kind of representations (specifically, those with qualitative character) 14 See Lavie (1995, 2005, 2007), and my (2010) for its relevance to philosophy.

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that we might be able to consciously entertain? Prinz (2007, 2010b, 2011, 2012)

has offered a response to this question, based on earlier work by Jackendoff

(1987). As Prinz points out, it is widely accepted that the visual system is

hierarchically organized. At the lowest level of complexity, he continues,

neurons in the visual cortex are coded to respond to specific stimulus features

such as edges or shapes. At the next level in the hierarchy (which he identifies as

the ‘Intermediate Level’), these features are connected into coherent

representations, including representations of depth, figure-ground separation,

and so on. Prinz claims that the representations at this level are specific to the

perceiver’s vantage point and it is only at the next, and final level, or stage of

processing, that abstraction from this perspective is achieved in order to support

object recognition. Prinz, then, supports Jackendoff’s contention that, ‘of the

three levels…it is the intermediate level that best corresponds to what people

report in conscious experience’ (2010, p. 3).

The purpose here is not to endorse the specifics of this particular account

of visual representations (with qualitative character) as contenders for conscious

perception. Indeed, it is likely that any extant theory of the phenomenal character

of visual processing will eventually be overturned. Nevertheless, it provides us

with a reasonable ‘place-holder’ for the first of the two minimum requirements

for a theory of consciousness: the what. Fulfilling the second condition, the how,

requires accounting for the fact that we only consciously entertain some of these

representations. My overall positive project, then, is to argue that the difference

between conscious and unconscious representations of supraliminally presented

visual objects is attention. However as I stated at the outset I’ll settle, for now, on

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showing that there’s no compelling evidence against the notion that attention is

minimally sufficient for consciousness.

4. Is Attention Sufficient for Consciousness?

Clearly, any complete account of the connection between attention and

consciousness will have to keep track of a large number of moving parts.

Nevertheless, it is arguable that the issue that looms largest is the possibility of

attention without awareness; specifically those cases where a subject seems able

to attend to a target in the complete absence of consciousness (of the target).

Indeed, no less an authority on these issues than Bob Kentridge (2011) claims

that, ‘these cases are the crucial ones for our attempt to understand the

relationship between attention and consciousness.’ (P. 238) It is against these

cases, then, that I shall attempt to set out my stall.

In a series of, by now, well-known experimental trials (Kentridge, et al,

2004), blindsight subject, GY, was prompted by visual cues to attend to an on-

screen target object presented to his blindfield. Blindsight is the name given to

the condition affecting those with damage to the primary visual cortex, V1 (or its

afferents), such that sufferers retain the ability to detect and discriminate visual

objects presented to portions of their visual field (scotoma) in which they declare

a lack of awareness15. Hence, it was expected that GY would indeed be unaware

of any target presented to his blindfield.

15 There are some blindsight subjects, GY included, who sometimes claim to be ‘aware’ of objects, presented in their scotoma, with a fast onset or offset.

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In each trial of the experiment GY was instructed to foveate on an

onscreen fixation spot, which had a black arrow (the cue) over it, pointing to one

of two possible target locations (each 60 from fixation; either 300 to the right of the

vertical meridian, or 150 below the horizon), in his blindfield, for 150ms. After the

offset of the cue, the fixation spot was presented alone for either 50ms or 300ms,

followed by the presentation of the target. The target, a black bar, was presented

either vertically or horizontally at one of the two possible locations, and was

accompanied by an audible tone. In 80% of the trials, the arrow correctly

indicated the position in which the target would appear (‘valid’ cues), in the

other 20%, the arrow’s cueing direction was misleading (invalid cues). (Ibid.)16

GY was able to discriminate the target orientation, in all cueing

conditions, at a rate significantly higher than chance17. Furthermore, he had a

higher rate of accuracy, and speed, in the valid trials, when compared to the

invalid ones (Ibid. p.834). GY’s increased speed and accuracy at discriminating

targets with the valid cues appears to be attention based.

GY’s performance on these tasks satisfies our operational definition of

attention, without meeting our operational definition of consciousness, so we

have clear empirical counterexamples to the claim that attention is sufficient for

However, GY has described this experience as akin to ‘waving your hand in front of your eyes when they are closed.’ (Weiskrantz, 1997, p.145) Where necessary, experiments employing these blindsighters are controlled to account for this phenomenon. See §5.3 below, for more details. 16 These experiments are often called ‘Posner paradigm’ cueing experiments after Posner’s ground-breaking research. See, for instance, Posner (1980). 17 The authors argue that these results cannot be explained in terms of a trade-off between reaction times (RT) and accuracy of discrimination because GY was, if anything,’ faster at correctly discriminating target orientation when the cue was valid.

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consciousness. In the next section, however, I look at a widely accepted model of

attention that, I argue, attenuates the results of these experiments.

5. The ‘Science Bit’

5.1 A Model of Attention

At any moment in our everyday experience, a bewildering number of

objects (‘targets’ and non-targets,’ or ‘distractors’ alike) will likely ‘compete’ for

our visual attention, and it’s widely accepted by psychologists that this process is

influenced by two factors: ‘top-down’ and ‘bottom-up’ selection18. In other

words, attention can be shifted voluntarily, in a goal-directed manner

(endogenously), or it can be ‘captured’ by environmental stimuli (exogenously).

A prior representation of some aspect(s) of information (‘perceptual set’) about

an object, such as its colour, shape, location, or motion, can bias our attentional

processing, allowing us heightened capacities of detection and discrimination

(see Kentridge, et al, 2004, discussed above). On the other hand, a distinctive

stimulus, or a sudden movement can automatically commandeer our attentional

processing, irrespective of our current preoccupations19. Put another way, it is

not unusual to find one’s attention drawn to the sudden onset of a visual 18 The terminology, ‘bottom-up’ and ‘top-down,’ is not meant to deny that such processing involves feedback pathways in the visual cortex. Rather it is used to mark the contrast, respectively, between automatic and voluntary processing. 19 Nevertheless, we are more likely to attend to distinctive stimuli when they are relevant to our current interests. This kind of exogenously controlled orienting of attention has been called ‘contingent’ to contrast it with the kind of ‘critical’ stimuli that we are alerted to that are entirely unrelated to our current cognitive concerns.

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stimulus, for instance, even when one is concentrating on a stimulus in another

part of the visual field.

In everyday life, visual attention is controlled by both cognitive (TOP-

DOWN) factors, such as knowledge, expectation and current goals, and

BOTTOM-UP factors that reflect sensory stimulation. Other factors that

affect attention, such as novelty and unexpectedness, reflect an

interaction between cognitive and sensory influences. The dynamic

interaction of these factors controls where, how and to what we pay

attention in the visual environment. (Corbetta and Shulman, 2002, p. 201)

In addition to this widespread agreement about the modulating effects of

endogenous and exogenous factors on attention orienting, it is also widely

acknowledged (Posner, p. viii, in Wright and Ward, 2008), that two, partially

segregated, cortical networks mediate these attentional functions. One of these, a

bilateral, ‘dorsal network,’ including the intraparietal cortex (Intraparietal sulcus,

or IPs) and the superior frontal cortex (frontal eye fields, or FEF), is primarily

involved in goal-oriented (top-down) attention shifts (or selection of stimuli).

The other system is a right-lateralized, ‘ventral network,20’ including the

temperoparietal cortex (temperoparietal junction, or TPJ), and inferior frontal

cortex (ventral frontal cortex, or VFC), which is primarily involved in stimulus-

driven (bottom-up) visual attention orienting, particularly to unexpected stimuli.

(Corbetta and Shulman, 2002).

20 The terms ‘dorsal’ and ‘ventral,’ here, should not be confused with Desimone and Duncan’s (1995) distinction. Accordingly I shall hereby respectively refer to these networks as ‘endogenous’ and ‘exogenous.’

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The endogenous network, or sub-system, shows an increase in cortical

activity during attention experiments involving visual cues, indicating the

location a target is due to appear at before it is actually presented, and hence,

where attention is to be voluntarily oriented. As Corbetta and Shulman (2002)

point out, experimentally, one can separate the function of generating and

maintaining an attentional set21 from the top-down effects that that set has on the

cortical activity resulting from target detection. The former control signals

proceed from the IPs to the FEF, which in turn, are directed to the visual cortex.

Accordingly, ‘[s]everal researchers have suggested that the dorsal [endogenous]

network mediates ‘pure’ voluntary attention control.’ (Wright and Ward, 2008, p.

183)

The exogenous network, or sub-system, on the other hand, shows an

increase in cortical activity following the detection of visual stimuli, particularly

when these stimuli are salient or surprising. For instance, in the case of ‘Posner

paradigm’ cueing experiments,22 subjects have to reorient attention from

locations indicated by invalid cues to the correct target location. The exogenous

network, then, exhibits increased activity for target detection, but, unlike the

endogenous sub-system, it does not do so for the presentation of the cues (Ibid.).

The idea, then, is that in ordinary vision, the orienting of attention is

always mediated by the interaction of these two sub-systems. The endogenous

network is engaged in the top-down processing of the attentional set, and is 21 Corbetta and Shulman define ‘perceptual set’ as the representation of advance information about a visual stimulus, ‘motor set’ as the representation of the relevant behavioural response to that information, and ‘attentional set’ to define, ‘the representations involved in the selection of task-relevant stimuli and responses.’

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modulated, in turn, by the detection of visual stimuli. The exogenous network,

on the other hand, engages in the detection of novel (and potentially dangerous)

stimuli. In such cases, experimental evidence suggests that the function of the

latter network is to break and redirect current task-related attention.

[T]he ventral [exogenous] network serves as an alerting system that

detects behaviourally relevant stimuli in the environment, but is not

equipped with high-resolution spatial sensors. Once a relevant stimulus

is detected, its precise localization depends on the dorsal IPs-FEF system.

A related hypothesis is that the TPJ-VFC system acts as a circuit breaker of

ongoing activity when a behaviourally relevant stimulus is detected [my

emphasis]. When subjects detect a low-frequency or unexpected event,

they must break the current attentional set and adopt a new one on the

basis of the incoming stimulus. (Corbetta and Shulman, 2002, p. 211)

Corbetta and Shulman, then, have offered us an account of attention in

operational terms, and provided a model of the sub-serving neural networks that

explain the relevant behaviour.

5.2 Empirical Implications

This now widely acknowledged model of (covert) orienting of visual

attention has important implications for claims about the relationship between

attention and awareness. If ordinary orienting of attention requires the functional

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overlapping of both sub-systems, and if (per my larger project) attention is

(necessary and) sufficient for consciousness, then we might ask what would

follow if either sub-system failed to function properly? One obvious possibility is

that a subject would suffer an attendant loss of awareness. This prediction

appears to dovetail with empirical research on unilateral spatial neglect.

Some unfortunate subjects, suffering from unilateral brain trauma,

‘neglect’ stimuli in the contralesional side of their visual space. Some of these

‘hemi-neglect’ subjects also suffer accompanying visual field deficits. In other

words, they disavow any experience of stimuli on this side of their visual space.

Hence a patient afflicted by a right-hemisphere cortical lesion, will seemingly

ignore the food on the left side of her plate, etc. (see Weiskrantz, 1997 for more

details); and also suffer motor deficits on the same side. In addition to these

behavioural issues, neglect patients appear to be powerfully attracted to stimuli

on the ipsilesional side of space.

Although it has been postulated that spatial neglect results from damage

to the dorsal IPs-FEF network, Corbetta and Shulman (2002) argue that the best

fit for the data actually suggests an anatomical insult arising in the ventral TPJ-

VFC network instead. This accords well with the information that the lesions

leading to neglect are more often ventrally located and frequently involve the

TPJ. Furthermore, frontal cortex lesions are usually located in ‘right ventral

prefrontal and opercular cortex, rather than in the more dorsal FEF region.’

(p.212) Furthermore, during stimulus detection, activity in the TPJ is strongly

lateralized to the right, and neglect arises more frequently after damage to the

right hemisphere, rather than the left. (Ibid, p. 213)

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Finally, patients with neglect have deficits primarily in stimulus

detection rather than in top-down goal-directed orienting. Neglect

patients can voluntarily direct attention to the contralesional side,

consistent with sparing of the IPs-FEF network, and can use cognitive

cues to anchor attention to the left visual space during their

rehabilitation. (Op. Cit. p.213)

This case, then, offers research results in line with the prediction that, if

attention is (necessary and) sufficient for consciousness, then there will be an

attendant loss of awareness with an attentional impairment. But how does this

work in the earlier examples? After all, the experimental evidence offered by

Kentridge, et al. suggests that GY’s attentional system is fully functioning.

5.3 Functionality?

GY is capable of voluntarily orienting visual attention to a location within

his scotoma, as evidenced by the fact that Kentridge, et al. specifically used ‘a

Posner endogenous spatial cueing paradigm.’ (Kentridge, et al., 2004, p. 831,

emphasis mine) Furthermore, the test results are consistent with claims that

observers are better at detecting visual targets when they are offered information

about them in advance, allowing them to form a ‘perceptual set,’ which can be

utilized to ‘bias the processing of incoming visual information.’ (Corbetta and

Shulman, 2002, p. 202) In other words, we are more successful at detecting visual

targets when we know something about their features in advance, e.g., color,

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location, or motion. We can also agree that these tasks are anatomically specific

to the endogenous network; the exogenous, or bottom-up network is not directly

involved in the production and preservation of perceptual sets.

What should we say, though, about GY’s exogenous sub-system? As

Corbetta and Shulman argue, the exogenous sub-system of the attentional

network is modulated by the detection of currently unattended or low frequency

objects, as noted above.23 It might arouse one’s suspicion, then, to know that GY

exhibited some form of awareness of objects, in his blindfield, during tests

designed by Weiskrantz. Moreover, his experiences appeared to be veridical, that

is, his avowals of awareness were in accord with his discriminatory prowess. For

example, in one experimental set-up GY was asked to indicate, using one of two

keys, the direction in which a target moved. With another two keys he was to

indicate whether or not he had any form of awareness of the target. He was not

only highly accurate with his discriminations, but his claims of awareness

matched the movement of the target (Weiskrantz, 1997, p.145).

GY says of such experiences that it is like ‘waving your hand in front of

your eyes when they are closed…But that isn’t a fair comparison to make…I

mean I can’t describe something I don’t understand myself. (Ibid.) Clearly, GY’s

awareness of objects in his blindfield is far from paradigmatic. Nevertheless,

there is clearly ‘something that it is like’ for him. How can we explain this?

GY only ever acknowledges awareness of objects in his scotoma when

they are spatially or temporally transient. Indeed, in Weiskrantz’s experiments

measuring GY’s ability to discriminate the direction in which targets were

moving across his blindfield, GY would only acknowledge “awareness” of them 23 See §5.1 above.

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when they moved at a rate of 10o/sec. or more, and deviated from a regular path

by roughly 20o (Ibid.). Similar results were obtained for targets with a fast onset

or offset.

Now, recall that the key function of the exogenous sub-system is to direct

attention to unexpected, behaviorally significant objects. The fact that GY only

acknowledges awareness of moving targets with a high velocity, or stationary

targets with fast onset/offset, suggests that at least this function of his exogenous

sub-system is preserved. This is important, though, because Kentridge, et al.

(2004) specifically controlled their experiments to avoid the former kind of

targets. Indeed they were explicit that they ‘used ramped, rather than abrupt

onsets and offsets, as the latter have been shown to contribute to awareness of

stimuli. (p. 833)

In ordinary vision the orienting of attention is mediated by both the

endogenous and exogenous sub-systems, so testing GY with stationary stimuli

without abrupt onsets/offsets amounts to functionally isolating the two systems,

and focusing only on the former. Consequently, whilst he is able to entertain a

rudimentary level of experience for fast-moving targets, it is possible that his

performance for less salient (whilst still behaviorally significant) stimuli could be

the result of an impaired exogenous sub-system. And if this is so, then it is

unsurprising that GY’s consciousness is compromised.

Nonetheless, in the absence of independent evidence, this is open to the

charge that it is mere speculation masquerading as an argument; only the

uncritical are likely to be moved by the mere suspicion of injury. But the point

may be moot anyway given that, whilst neglect is acknowledged to be an

attentional issue, blindsight is not.

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Whereas neurons in the visual cortex also play a role in attentional

selection of inputs, they are not considered to be part of the purely

attentional mechanism that mediates [attention]. Serences and Yantis

(2006) described this distinction as one between the source of attention

control…and the target of attention control signals (e.g., visual cortical

processing). It could also be thought of as the distinction between

mechanisms of attention shifting and consequence of these shifts […].

(Wright and Ward, 2008, p. 174)

5.4 The ‘Threshold’ of Consciousness?

Focusing on the functionality of GY’s attentional network, in isolation, then, is

most likely mistaken. But it does point us in the right direction. Indeed, what

should concern us, instead, is the condition of the connection(s) between GY’s

attentional system and his visual cortex. This is because the experimental

conclusions are consistent with the kind of outcome one might expect from

compromised connections between one’s attentional network (specifically the

exogenous sub-system), ‘and the target of attention control signals [i.e., the

relevant visual representations].’ Attending, after all, amounts to more than mere

activation of the relevant cognitive system.

Recall that blindsight subjects suffer damage to the primary visual cortex

(V1), or its afferents. GY does retain some form of sensory awareness for visual

objects, but only when they are temporally or spatially transient, and Kentridge,

et al. specifically controlled for these conditions. Under all other testing

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conditions GY is unaware of the targets. So even if his attentional system itself is

fully functional, it is highly plausible that it is not correctly connected to exploit

the relevant kind of ‘raw materials:’ intermediate-level visual representations:

Consequently, Kentridge, et al. have not offered us evidence of attention in the

absence of awareness.

To put the point another way24, what we require from a theory of

consciousness is an explanation of both the ‘what’ and the ‘how:’ that is, what we

are conscious of and how we become conscious of it? In GY’s case, his attentional

networks (the ‘how’) are unable to access, and hence process the requisite

representational inputs (the ‘what’). In support of this, it’s worth noting that,

…the eye connects in parallel to 9 other targets in the brain aside from

V1, although of course these pathways interact with each other via other

connexions…Thus when V1 is damaged or blocked…information from the

eye can still readily reach the brain via these other routes. (Weiskrantz,

1997, p. 16)

But it is important to note that this is not a ‘threshold claim.’ GY’s ability to

detect and discriminate targets in his blindfield, in the absence of awareness, is

not due to a dwindling of normal capacity. It is not that this re-routing results in

a weaker version of the relevant visual representations, which are then unable to

reach the ‘threshold’ for consciousness. Instead, there’s a crucial qualitative

difference between the normal and pathological cases:

24 See §3 above.

22

…some blindsight patients, especially with rapidly moving or suddenly

appearing stimuli, have a kind of ‘awareness.’ Under other conditions,

excellent discrimination is still possible even though the subject has no

awareness whatever of moving stimuli. We have measured the stimulus

parameters for moving stimuli for one blindsight subject, G.Y., in

conditions where he acknowledges some awareness, and in other

conditions where he has no awareness whatsoever…the results suggest that

there is a qualitative difference between the two functions, that the curve

relating discrimination success to velocity and contrast of the moving

stimulus when the subject is unaware is not just a pale shadow of the curve

for when he is aware. P.41

Suppose, for the sake of illustration, that preparing a proper espresso requires

processing specific ingredients through a purpose-built machine. Now imagine a

customer, complaining to a sales assistant that his recently purchased espresso

maker is faulty: its end result always causes him a headache. The sales assistant

asks the customer some questions; has he changed his water source? Is the filter

contaminated? Is the pressure setting correct? And so on. Eventually, after

ensuring that all the relevant parameters are in place, she adds coffee to the

appropriate compartment, tamps it down, and finally, offers the customer the

ensuing espresso. The customer sips his coffee, and, after a few minutes, admits

that he feels fine: no headache. He leaves, with the same espresso maker,

somewhat mystified. A week later, our embarrassed but enlightened customer

comes back to the store to admit that he had been accidentally using his wife’s

decaffeinated coffee all along. The point of this, admittedly, toy story, is that an

23

espresso is the end product of a process that requires the right kind of

machinery, and the qualitatively correct ingredient. The espresso maker was

fully functional the entire time, but it wasn’t processing the qualitatively correct,

in this case caffeinated, ingredient. Likewise, GY’s attentional network may be

able to process properly, but unless it has causal connections to the appropriate

targets, the qualitatively correct kind of visual representations,25 it is not attending

in the appropriate sense; it is, like the espresso maker without caffeinated coffee,

merely ‘going through the motions.’ Ultimately, then, there are good grounds, if

you’ll pardon the pun, to resist the claim that we have been offered experimental

evidence that attention is not sufficient for consciousness.

6. Sufficiency Conditions

6.1 Minimal Sufficiency

So far, then, the investigation has focused on purported cases of attention

without awareness, which involve a blindsight subject. I have offered an

inference to the best explanation, which denies that these are actually cases of

normal attention. That is, whilst the subject’s attentional network might be fully

functional, it isn’t processing the qualitatively relevant representational targets.

25 Recall that GY was able to discriminate targets with greater speed and accuracy in the valid trials, when compared to the invalid ones. Clearly, his attentional system is causally connected to some kind of information about the visual targets. My claim, here, is that GY plausibly suffers compromised connections to the qualitatively right kind (“Intermediate level”?) of visual targets.

24

Nevertheless, one might think that this conclusion is neither surprising

nor illuminating given that the experimental evidence on offer is presented from

a pathological case. Is this right, and if so, can we counter cases of apparent

attention without awareness in normal subjects? Before addressing these issues

directly, it is worth saying some more about sufficiency conditions, generally.

One way to do this is to distinguish between the core and total26 neural

bases of consciousness. Block (2009), for instance, says:

The total neural basis of a state with phenomenal character C is itself

sufficient for the instantiation of C. The core neural basis of a state with

phenomenal character C is the part of the total neural basis that

distinguishes states with C from states with other phenomenal characters or

phenomenal contents, for example the experience as of a face from the

experience as of a house. p. 482

To put the present project in Block’s terms, then, the total neural basis of a

conscious experience as of a face, involves the attentional system processing the

qualitatively relevant visual representations (the core neural basis of that state).

Nonetheless, using the distinction in this way turns out to be too fine-

grained for our purposes; what we are attempting to do is identify the core neural

processes that suffice for phenomenal states simpliciter. Indeed, in doing the

latter, we can claim that the attentional system processing the relevant visual

information is the core neural basis of a conscious experience. The total neural

26 This distinction is adapted from Shoemaker (1981), and is also used by Block 2007), and Chalmers (2000).

25

basis involves all the neural states (including core states) that provide the relevant

background conditions for a conscious experience.

Even with this shift in perspective, we can still follow Block (Ibid.) as he

introduces an additional distinction, this time between the causal and constitutive

conditions of consciousness: the core neural basis of consciousness is constitutive

of consciousness, whereas the total neural basis (minus the core) provides the

relevant causal, background conditions for (the core, and hence) consciousness.

This distinction seems to be in good standing. Indeed, without it it is hard to see

how progress could be made in identifying the core physical foundations of

consciousness. Besides which, as a number of authors have noted, nobody thinks

that the core neural basis of consciousness could be excised from a brain, and

under such conditions, still be sufficient for consciousness.

This coarse-grained notion of the core neural basis of consciousness, then,

is essentially stating the minimally sufficient conditions for consciousness.27

6.2 Range of cases

The argument thus far, then, is that attention is minimally sufficient for

consciousness. But, as Chalmers (2000) asks, over what range of cases should we

expect that relationship to hold?

The question is then how to distinguish the core from the background. It

seems that what is required for an NCC [neural correlate of consciousness]

(in the “core” sense) is not that it correlate with consciousness across any

27 See, Chalmers (2000) for a more detailed account of this kind.

26

possible conditions, but rather that it correlate across some constrained

range of cases in which some aspects of normal brain functioning are held

constant.

Following from this, Chalmers offers us an analysis of the kinds of instances in

which we should expect consciousness to hold, running the gamut from normal

brains with normal inputs, to abnormal brains with abnormal inputs. Well,

common sense allows for a lack of phenomenality in cases where the core neural

basis of consciousness is excised from the rest of the brain. And this is just as

likely to hold for less drastic lesions: any time the total neural realizers are unable

to provide the relevant causal support, whether due to damage ‘upstream’ or

‘downstream’ of the core, then all bets are off.

Nonetheless, we needn’t cover all the cases, here, in order to show that a

functioning attentional system, without attendant consciousness, is fully

consistent with the claim that attention is minimally sufficient for consciousness.

The case can best be made, I think, by focusing on normal (i.e., non-pathological)

subjects with ‘ecologically invalid’ inputs (Ibid.).

6.3 Attended but unseen, for normal subjects

In a now infamous experiment, Jiang et al. (2006) used the interoccular

suppression paradigm to test the possibility that attention influences

performance in detection tests with ‘invisible’ cues. Interoccular suppression

involves presenting a high-contrast stimulus to one of the subject’s eyes, and a

different, low-contrast, test stimulus to the other eye. The high-contrast stimulus

27

has the effect of masking, or making ‘invisible,’ the other, low-contrast test

stimulus. This method allows for stimuli presentation over lengthy intervals;

long enough, that is, for attention to target representations of the stimuli.

The Jiang et al. study is notable for its use of nude images as the test

stimuli28. The results showed that the strong interoccular suppression did indeed

mask the nudes. However, in the following detection tests, subjects showed

superior performance for those targets presented in the location of the nudes.

Jiang et al. concluded that the nudes acted as cues, influencing spatial attention,

even though the subjects were not conscious of them. This, then, is an apparent

case of attention without awareness in normal subjects, and, perhaps, presents a

stronger challenge to our position than those cases involving subjects with

neurological disorders.29

It seems to me, however, that this case and other purported examples of

attention without awareness, in normal subjects (see, for instance, Kentridge,

2011), are susceptible to the same argument I offered in §5.3 above. For example,

in a commentary on interoccular suppression, Logothetis (1998) remarks that,

Extensive psychophysical research has showed that the perceptual

disappearance of a pattern during dichoptic stimulation ought to be due to

a disruption of the normal flow of visual processing within or beyond the

primary visual cortex. P.5

28 The relevant effects were only found for those cases where the nude matched the subject’s sexual preference. See, Jiang et al. (2006). 29 Kentridge (2011) acknowledges this possibility; ‘One…objection to…our studies…is that our only subject was a patient with a rare neurological condition…Although logically we had demonstrated that attention does not always give rise to awareness it is something of a leap to extrapolate this finding to the general population.’

28

Recall that the blindsight studies performed by Kentridge et al. (2004) involve a

subject, GY, who has sustained damage to his visual cortex. Whilst it may be the

case that GY’s attentional system is somehow processing the visual

representations that bypass his striate cortex, they are of the qualitatively wrong

kind for consciousness. Now in those scenarios with normal subjects, the same

problem is present but just by different means: the visual inputs are, in

Chalmers’ terms, ‘ecologically invalid.’ In other words, the experimental

conditions the subjects are exposed to are always carefully calibrated to disrupt

normal visual processing.

We could of course pause, at this point, to provide a philosophical account

of normal vision, but it’s not necessary. Whatever that ultimately amounts to,

there can be no doubt that the interoccular suppression paradigm, masking

studies, and so on are explicitly chosen by psychologists to subvert normal vision:

that is precisely their experimental aim. And this, I propose, is why the argument

I offered against the pathological case generalizes. As Weiskrantz (1997) argues,

There is…reason to question whether the idea of degraded normal function

is itself a good model for anything, …in neuropsychology… All tasks

consist of constellations of demands and capacities…But these do not

necessarily degrade equally with signal strength…A degraded normal task

is not necessarily just a ‘weaker’ version of the strong normal task. Even

within a single restricted domain, more than one process will be involved.

In degrading from strong into weak versions of a task with normal subjects,

it is possible that one is switching from one form of process to a

qualitatively quite different one…And so it does not follow that even when

29

successful simulation of a deficit in a patient has been achieved by

‘weakening’ normal function, the residual function being simulated

necessarily is qualitatively the same as normal ‘unweakened’ function. p. 43

7. Concluding remarks

Investigating the nature of the relationship between attention and

awareness has a long lineage, and not without reason. At a minimum, insights

into either domain potentially promise double dividends. The most promising

possibility, however, has always been that attention is both necessary and

sufficient for consciousness. Should this prove to be the case then we stand to

secure a free explanatory trade-up from a theory of attention to a theory of

consciousness (Mole, 2008a).

Nevertheless, the empirical evidence has always appeared to count

against this possibility, especially in terms of the sufficiency condition. Early

experiments of this kind, studying subjects with neurological disorders,

appeared to produce proof of dissociations between attention and awareness.

Following from these, a number of more recent studies have obtained similar

results for normal subjects.

However, once we look at the commitments required for claiming that

attention is (minimally) sufficient for consciousness, it appears that none of these

conditions are satisfied in any of the experiments. Though the causal conditions

differ across the cases, the argument generalizes; they all involve subjects whose

attentional systems are engaged in attempting to process the qualitatively wrong

30

kind of visual inputs. Consequently, if consciousness requires the attentional

processing of the relevant level of visual representations, we do not possess

evidence against the notion that attention is sufficient for consciousness.

31

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