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The role of cognitive biases andpersonality variables in subclinicaldelusional ideationMahesh Menon a b c e , Lena Catherine Quilty d , John AnthonyZawadzki a b c , Todd Stephen Woodward e , Helen MoriahSokolowski f , Heather Shirley Boon g & Albert Hung Choy Wonga b ca Schizophrenia Program and Research Imaging Centre, Centrefor Addiction & Mental Health, Toronto, Canadab Department of Psychiatry, University of Toronto, Toronto,Canadac Institute of Medical Science, University of Toronto, Toronto,Canadad Clinical Research Department, Centre for Addiction & MentalHealth, Toronto, Canadae Department of Psychiatry, University of British Columbia,Vancouver, Canadaf Department of Psychology, University of Western Ontario,London, Canadag Leslie Dan Faculty of Pharmacy, University of Toronto,Toronto, Canada

Version of record first published: 04 Jul 2012

To cite this article: Mahesh Menon, Lena Catherine Quilty, John Anthony Zawadzki, Todd StephenWoodward, Helen Moriah Sokolowski, Heather Shirley Boon & Albert Hung Choy Wong (2012): Therole of cognitive biases and personality variables in subclinical delusional ideation, CognitiveNeuropsychiatry, DOI:10.1080/13546805.2012.692873

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The role of cognitive biases and personality variables in

subclinical delusional ideation

Mahesh Menon1,2,3,5, Lena Catherine Quilty4, John AnthonyZawadzki1,2,3, Todd Stephen Woodward5, Helen MoriahSokolowski6, Heather Shirley Boon7, and Albert Hung ChoyWong1,2,3

1Schizophrenia Program and Research Imaging Centre, Centre for

Addiction & Mental Health, Toronto, Canada2Department of Psychiatry, University of Toronto, Toronto, Canada3Institute of Medical Science, University of Toronto, Toronto, Canada4Clinical Research Department, Centre for Addiction & Mental

Health, Toronto, Canada5Department of Psychiatry, University of British Columbia,

Vancouver, Canada6Department of Psychology, University of Western Ontario, London,

Canada7Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto,

Canada

Introduction. A number of cognitive biases, most notably a data gathering biascharacterised by ‘‘jumping to conclusions’’ (JTC), and the ‘‘bias against disconfir-matory evidence’’ (BADE), have been shown to be associated with delusions and

Correspondence should be addressed to Schizophrenia Program & PET Centre, Centre

for Addiction & Mental Health, 250 College St, Toronto, M5T 1R8, Canada.

E-mail: Mahesh_menon@camh.net

The authors would like to thank Sarah Mathewson, Dr Paul Fletcher and Wanna Mar for their

assistance with data collection on this study. The study was partially funded by a new staff startup

grant to MM from the Centre for Addiction & Mental Health, and a summer student fellowship

from the Leslie Dan Faculty of Pharmacy, University of Toronto. HMS was supported by an

Undergraduate Research Award from the Institute of Medical Sciences, University of Toronto.

AHCW is supported by a CIHR Clinician Scientist Fellowship and an NARSAD Independent

Investigator Award. All authors contributed to and approved the final manuscript. All authors

declare that they have no conflict of interest.

COGNITIVE NEUROPSYCHIATRY

2012, 1�11, iFirst

# 2012 Psychology Press, an imprint of the Taylor & Francis Group, an Informa business

http://www.psypress.com/cogneuropsychiatry http://dx.doi.org/10.1080/13546805.2012.692873

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subclinical delusional ideation. Certain personality variables, particularly ‘‘open-ness to experience’’, are thought to be associated with schizotypy.Methods. Using structural equation modelling, we examined the associationbetween two higher order subfactors (‘‘aspects’’) of ‘‘openness to experience’’(labelled ‘‘openness’’ and ‘‘intellect’’), these cognitive biases, and their relationshipto subclinical delusional ideation in 121 healthy, nonpsychiatric controls.Results. Our results suggest that cognitive biases (specifically the data gathering biasand BADE) and the ‘‘openness’’ aspect are independently associated withsubclinical delusional ideation, and the data gathering bias is weakly associatedwith ‘‘positive schizotypy’’. ‘‘Intellect’’ is negatively associated with delusionalideation and might play a potential protective role.Conclusions. Cognitive biases and personality are likely to be independent riskfactors for the development of delusions.

Keywords: Bias against disconfirmatory evidence; Cognitive biases; Delusions;

‘‘Jumping to conclusions’’; Openness; Personality; Subclinical delusional ideation.

INTRODUCTION

A growing body of evidence suggests that psychosis may exist as a

continuum, with illnesses like schizophrenia at one end (Kendler, Neale, &

Walsh, 1995), and schizotypal and paranoid personality disorder represent-

ing milder manifestations of the same aetiological processes (Meehl, 1962).

Consistent with this, epidemiological evidence indicates that subclinical

manifestations of psychotic symptoms such as delusions and hallucinations

occur with varying degrees of frequency and severity even within the

nonclinical, psychiatrically ‘‘healthy’’ population, and may be indicators of

schizotypy (Johns & van Os, 2001; van Os, Hanssen, Bijl, & Ravelli, 2000).

An examination of neurocognitive vulnerabilities and strengths within this

group may increase our understanding of the underlying cognitive processes

associated with more severe forms of psychosis, as well as of possible

protective factors that might prevent transition to frank psychosis in

vulnerable individuals.

Scales measuring schizotypy, such as the Schizotypal Personality Ques-

tionnaire (SPQ; Raine, 1991) consider schizotypy a multidimensional

construct, with the ‘‘odd beliefs/magical thinking’’ subscale most closely

resembling delusions, and the ‘‘unusual perceptions’’ most resembling

hallucinations. Newer instruments, such as the Peters Delusions Inventory

(PDI; Peters, Joseph, Day, & Garety, 2004) focus on subclinical forms of

common delusional subtypes. Both instruments have been used to examine

cognitive and personality variables in association with schizotypy and

subclinical delusional ideation.

Cognitive biases play an important role in the formation (Broome et al.,

2004) and maintenance of delusions (Menon, Mizrahi, & Kapur, 2008). Two

of the most consistently replicated cognitive biases are the data gathering

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bias, characterised by ‘‘jumping to conclusions’’ on probabilistic reasoning

tasks (see Garety & Freeman, 1999, for a review), and a bias against

disconfirmatory evidence (BADE; Woodward, Moritz, & Chen, 2006;

Woodward, Moritz, Cuttler, & Whitman, 2006; Woodward, Moritz, Menon,

& Klinge, 2008). Both cognitive biases are also associated with the presenceof subclinical delusional ideation (Warman & Martin, 2006a, 2006b;

Woodward, Buchy, Moritz, & Liotti, 2007), and the BADE bias is associated

with schizotypy (Buchy, Woodward, & Liotti, 2007).

Besides cognitive biases, personality likely presents a key variable

influencing the development of subclinical delusional ideation. Research

has examined the relationship between personality variables such as the ‘‘big

five’’ and psychosis vulnerability. Of the ‘‘big five’’ factors, ‘‘openness to

experience’’ has been found to be most closely associated with schizotypy(Johns & van Os, 2001), although this relationship has not been consistently

demonstrated (Miller & Tal, 2007). One possible reason is that ‘‘openness’’

appears to be a multidimensional construct consisting of two higher order

subfactors or ‘‘aspects’’ labelled ‘‘openness’’ and ‘‘intellect’’ (DeYoung,

Quilty, & Peterson, 2007). ‘‘Intellect’’ encompasses intellectual engagement

and perceived intellect, and is associated with general intelligence (g)

(DeYoung, Quilty, Peterson, & Gray, in press), whereas ‘‘openness’’

encompasses the domains of aesthetics, fantasy proneness, and willingnessto engage with novel stimuli or beliefs. We therefore hypothesise that only the

‘‘openness’’ aspect would be associated with schizotypy and, by extension,

with subclinical delusional ideation.

Personality variables, having a strong genetic component (Plomin, Owen,

& McGuffin, 1994; Tellegen et al., 1988), may influence or be related to

psychosis vulnerability. Although cognitive biases have been studied in

relation to psychosis vulnerability, the relationship between cognitive biases

and personality, as well as the nature of their relationship to psychosisvulnerability or subclinical delusions, has not been explored in detail.

Cognitive biases might independently influence psychosis vulnerability, or

mediate the relationship between personality and psychosis vulnerability. To

explore the effects of personality on cognitive biases and psychosis

vulnerability concurrently, we examined the impact of cognitive biases and

both aspects of ‘‘openness to experience’’ on subclinical delusional ideation

and schizotypy. Since these cognitive biases have been thought to be

specifically associated with delusions, we hypothesised associations betweenboth sets of variables (cognitive biases and ‘‘openness’’) and the PDI, and

with only the ‘‘odd beliefs/magical ideation’’ but not ‘‘unusual perceptions’’

subscales of the SPQ. To evaluate whether personality and cognitive biases

were also related to each other or showed any mediating relationships, these

two sets of variables were evaluated simultaneously using structural equation

modelling (SEM).

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METHODS

Participants

We recruited 121 healthy participants with no history of psychiatric illness

through advertisements posted within and outside the University of Torontocampus. All participants were fluent in English, with no history of

psychiatric illness, serious head injury, or substance abuse. Data from three

participants were removed because of incomplete responses, and another

because of a psychiatric history, leaving a final sample of 117 participants.

Measures

Subclinical delusional ideation was measured using the PDI (Peters et al.,

2004) and schizotypal traits using the SPQ (Raine, 1991). Personality was

assessed using the Big Five Aspects Scale (DeYoung et al., 2007), which

examines the five factor model and the two aspects of each factor. We were

particularly interested in the ‘‘intellect’’ and ‘‘openness’’ aspects of the

‘‘openness to experience’’ factor.

Probabilistic reasoning task. This widely used task (Garety, Hemsley, &

Wessely, 1991; Moritz & Woodward, 2005; Startup, Freeman, & Garety,

2008) was adapted from earlier studies by our group (Menon et al., 2008;

Menon, Pomarol-Clotet, McKenna, & McCarthy, 2006). In brief,

participants are shown a pair of jars with two types of different coloured

beads in an equal and opposite ratio. One jar has a ratio of 60 red beads and

40 black beads (the ‘‘mostly red’’ jar), and the other contains 40 red beads to60 black beads (the ‘‘mostly black’’ jar). The jars are hidden behind a screen

and beads are presented to participants one at a time in a pseudorandom

sequence and then returned to the jar. Beads are presented until participants

decide which jar the beads come from. The number of draws to decision is

the variable of interest.

BADE task. The BADE task (Woodward et al., 2007; Woodward,

Moritz, & Chen, 2006) is an interactive computer-based test of inferential

reasoning. Participants are presented with a social situation in the form ofthree statements (clues), presented one at a time (e.g., Jane is very thin; Jane

is hungry; Jane lives on the street), and three possible interpretations (e.g.,

Jane is a model; Jane is homeless; Jane is a librarian). After each statement

the participant is required to rate the plausibility of each of the given

interpretations independent of the other two, using a sliding scale of 0 to 10.

A number of the trials feature scenarios designed to lure the participant

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towards one of the interpretations (e.g., ‘‘Jane is a model’’ is a ‘‘lure’’); the

third statement (e.g., ‘‘Jane lives on the street’’) provides disconfirmatory

evidence to test participant willingness to accept the new evidence and

change previous interpretations. The computerised BADE task consisted of

35 scenarios (trials), 20 that tested for a bias against disconfirmatoryevidence (where there is a distinct lure), 10 trials where two options remain

equally likely, and five filler trials (where the explanation that appeared

initially likely remains that way). These trials serve to provide variation in the

pattern of responding.

For each of the BADE trials, we calculated the reduction in confidence

between the first and third trials for the ‘‘lure’’ interpretations, as a ratio of

the increased confidence for the ‘‘true’’ interpretations, a measure we refer to

as the BADE ratio. A higher value indicates greater continued confidence inthe lure interpretation, indicative of the bias against disconfirmatory

information being presented.

Analysis

Our variables of interest were the PDI total score (a composite of total scores

on the conviction, preoccupation, and distress items), and the scores on the

‘‘unusual perceptions’’, and ‘‘odd beliefs’’ subscales of the SPQ (consisting of

9 and 7 items respectively). To evaluate the impact of personality and

cognitive biases on schizotypal features, we conducted a series of six path

models. In each model, ‘‘openness’’ and ‘‘intellect’’ served as antecedent

variables (as personality traits likely precede the development of cognitivereasoning strategies); cognitive biases assessed by the BADE and probabil-

istic reasoning tasks served as mediators in separate models. PDI total, SPQ

odd beliefs, and SPQ unusual perceptions scale scores served as outcome

variables in separate models. Age and sex were included as covariates in all

models. Due to the presence of significant multivariate nonnormality

(Mardia’s coefficient of multivariate kurtosis�6.81), path analyses were

conducted in MPlus, utilising robust maximum likelihood method of

estimation (Muthen & Muthen, 1998). Goodness of fit of path models canbe assessed using x2; Confirmatory Fit Index (CFI), with values�.90

indicating acceptable fit; and Root Mean Square Error of Approximation

(RMSEA), with values�.1 indicative of poor fit,B.08 acceptable fit, and

B.05 close fit (Hu & Bentler, 1999).

RESULTS

The final sample consisted of 117 individuals (77 women and 40 men), with a

mean age of 30.7 (SD�12.6; range�18�62), and 16.4 years of total formal

BIASES IN SUBCLINICAL DELUSIONS 5

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education (SD�3.4; range�10�25 years). On our measures of interest, our

participants showed mean scores of 14.8 (SD�12.3; range�0�60) on the

PDI, 1.7 (SD�1.9; range�0�7) on SPQ odd beliefs, and 1.8 (SD�1.8;

range�0�7) on SPQ unusual perceptions subscales. The mean ‘‘BADE

ratio’’ on the BADE task was �0.8 (SD�1.0; range��4.2 to 0.3), andmean number of draws to decision on the probabilistic reasoning task was 9

(SD�3.9; range�1�15). Path models are depicted in Figures 1 and 2. Age

and sex did not significantly predict cognitive biases or schizotypal features

(and are therefore omitted for clarity). The BADE bias (see Figure 1) was

specifically associated with subclinical delusional ideation (i.e., PDI total

and SPQ odd beliefs), but not subclinical hallucinations (i.e., SPQ unusual

perceptions). On the probabilistic reasoning task, only 2/117 of our

participants showed the ‘‘jumping to conclusions’’ (JTC) response pattern,operationalised as two or fewer draws-to-decision (Garety et al., 2005;

Startup et al., 2008). As depicted in Figure 2, the number of draws to

decision was negatively associated with PDI total score and SPQ unusual

perceptions (but fell just short of significance with SPQ odd beliefs scale). In

both models, openness independently and positively predicted PDI total

score; whereas intellect negatively predicted PDI total score (at trend levels

of p�.058 in Model 1, and at pB.05 in Model 2). These personality

variables were not significantly predictive of either of the SPQ scale scores.The cognitive biases did not mediate the relationship between personality

and delusions (Kraemer, Stice, Kazdin, Offord, & Kupfer, 2001), and neither

openness or intellect were associated with the cognitive biases.

To evaluate empirical support for our causal ordering of variables, we also

repeated the analyses using cognitive biases as antecedent variables and

personality variables as mediators. The fit of an alternate model in which

cognitive reasoning measures are modelled as antecedent variables and

personality traits as mediator variables resulted in a significant decrease in fit(i.e., a decrease in CFI �.01, as per Cheung & Rensvold, 2002, and an

Akaike Information Criterion of greater value). These results suggest that

these results are robust and that an alternate ordering of variables cannot be

empirically justified.

DISCUSSION

Our results suggest that the BADE bias, characterised by a reduced

weighting of disconfirmatory information, is specifically associated with

subclinical delusional ideation, but not perceptual abnormalities indicative

of subclinical hallucinations. Although only two of the participants showed

the JTC response pattern, the number of draws to decision is negatively

correlated with both subclinical delusions and hallucinations. This has

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(a)

Intellect

Openness

.05

BADE

.10

PDI Total Score.20**

.19

-.21*

.00

-.18

(b)

Intellect

Openness

.05

BADE

.10

SPQ Odd Beliefs.22**

.13

.05

.00

-.18

(c)

Intellect

Openness

.05

BADE

.02

SPQUnusual Perceptions

.07

-.04

-.05

.00

-.18

Figure 1. The prediction of schizotypal features with openness, intellect, and inferential reasoning

biases (BADE). Fit was equal and acceptable by all indices, due to the fact that models were just-

identified (i.e., the number of parameters to be estimated was equal to the degree of freedom; x2

undefined; CFI �1.00; RMSEA�.00). Covariates and error variables have been omitted for clarity.

*pB.05, **pB.01 for individual parameter estimates.

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(a)

Intellect

Openness

.04

Draws to Decision(JTC)

.11

PDI Total Score-.14**

.20**

-.27**

.01

.12

(b)

Intellect

Openness

.04

Draws to Decision(JTC)

.06

SPQ Odd Beliefs-.11

.13

.09

.01

.12

(c)

Intellect

Openness

.04

Draws to Decision(JTC)

.04

SPQUnusual Perceptions

-.18**

-.01

.01

.01

.12

Figure 2. The prediction of schizotypal features with openness, intellect, and probabilistic reasoning

biases (draws to decision). Fit was equal and acceptable by all indices, due to the fact that models were

just-identified (i.e., the number of parameters to be estimated was equal to the degree of freedom; x2

undefined; CFI �1.00; RMSEA�.00). Covariates and error variables have been omitted for clarity.

*p B.05, **pB.01 for individual parameter estimates.

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parallels with patient data, which indicates that the ‘‘data gathering bias’’

might be associated with positive symptoms in general, rather than just

delusions (Menon et al., 2006).

An interesting and unanswered question has centred on how the genes for

psychosis vulnerability have persisted in the gene pool, and one possible

hypothesis is that, in their attenuated form, the psychosis vulnerability genes

and the associated personality constructs (schizotypal traits) may confer

some evolutionary advantage (such as ‘‘creativity’’). Openness has also been

shown to be associated with traits such as creativity, and has been speculated

to mediate the ‘‘schizotypy�creativity’’ link (Miller & Tal, 2007). Our current

results may shed light on this issue as they suggest that it is the ‘‘openness’’

aspect which is associated specifically with the subclinical delusions, with

‘‘intellect’’ showing a negative correlation, suggesting that it might be a

protective factor. It is possible that positive schizotypy (measured by the two

SPQ subscales we considered) is a more general construct, with weaker

associations with these aspects of personality. Alternatively, although the

PDI and the SPQ ‘‘odd beliefs’’ subscale putatively measure similar

underlying constructs, we found stronger associations with the PDI scores.

This indicates that the PDI might be a better indicator of subclinical

delusional ideation, or that the composite score created (which integrates

information on conviction, distress, and preoccupation) better captures the

range of underlying phenotypic features of these beliefs.

Importantly, the results indicate that cognitive biases and personality are

not related to each other, but, rather, are independently associated with

subclinical ideation, and therefore likely to be independent risk factors for

the development of delusions.

Manuscript received 2 December 2011

Revised manuscript received 13 March 2012

First published online 4 July 2012

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