Personality and Individual Differences 45 (2008) 822–827

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Personality and Individual Differences

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Context binding and hallucination predisposition

Johanna C. Badcock a,b,d,*, Saruchi Chhabra c, Murray T. Maybery c, Georgie Paulik c,d

a Centre for Clinical Research in Neuropsychiatry/Graylands Hospital, Private mail bag No. 1, Claremont, WA 6910, Australiab School of Psychiatry and Clinical Neurosciences, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australiac School of Psychology, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australiad Shizophrenia Research Institute, Darlinghurst, NSW, Australia

a r t i c l e i n f o

Article history:Received 13 May 2008Received in revised form 11 August 2008Accepted 21 August 2008Available online 27 September 2008

Keywords:Hallucination predispositionHallucinationsSchizophreniaCognitionContext binding

0191-8869/$ - see front matter Crown Copyright � 2doi:10.1016/j.paid.2008.08.016

* Corresponding author. Address: Centre for Clinictry/Graylands Hospital, Private mail bag No. 1, Clarem+61 8 9347 6507; fax: +61 8 9384 5128.

E-mail address: johanna.badcock@uwa.edu.au (J.C

a b s t r a c t

Patients with schizophrenia and current auditory hallucinations exhibit a combination of deficits in con-text binding and intentional inhibition. Hallucinations also occur in the general population suggesting anunderlying continuity of causal mechanisms, however, these experiences may also differ (e.g., in fre-quency), indicating some differences in aetiology. The aim of this study was to examine the frequencyof hallucinatory experiences in healthy young adults and to assess whether difficulties in context bindingcharacterize individuals highly predisposed to hallucinations. A modified version of the Launay–Sladehallucination scale-revised, including an assessment of the frequency of hallucination experiences, wascompleted by 615 undergraduates from which sub-samples of high (n = 25) and low (n = 27) scorers weredrawn. Context memory ability was assessed using a voice–location binding task. The results showed thatthe frequency of hallucinations in high LSHS-R scorers was much less than that previously reported forindividuals with schizophrenia. Furthermore, no group differences in context memory binding wereobserved, nor any association between hallucination frequency and context binding difficulties. The con-tinuity model of hallucinations may overlook some important differences in hallucinatory experiences inthe general population versus psychosis.

Crown Copyright � 2008 Published by Elsevier Ltd. All rights reserved.

1. Introduction

We have previously proposed a model of auditory hallucina-tions (AH) in schizophrenia comprised of deficits in both contextmemory binding and intentional inhibition (Waters, Badcock,Michie, & Maybery, 2006a). As a result of these combined deficits,mental events are experienced as involuntary and intrusive and arenot correctly recognized because the necessary contextual cues(e.g., who was speaking, where and when) are missing or incom-plete. The relative risk of exhibiting these deficits has been shownto be significantly elevated in patients with active (i.e., frequent)AH compared to patients who are not currently hallucinating(Waters et al., 2006a). It is possible that this combination of deficitsunderpins all forms of hallucinations, however, this proposal hasnot been directly tested (Badcock & Maybery, 2005).

AH (‘voices’) also occur in the general population, includingchildren and adolescents, and do not necessarily presage mentalillness (McGee, Williams, & Poulton, 2000; Tien, 1991). Some re-search has emphasized that AH in patients and non-patients arebroadly similar in nature (Honig et al., 1998; Waters, Badcock, &

008 Published by Elsevier Ltd. All

al Research in Neuropsychia-ont, WA 6910, Australia. Tel.:

. Badcock).

Maybery, 2003a) suggesting that similar cognitive mechanismsmay be involved in their development. For example, healthy youngadults (undergraduates) with high scores on the Launey-Slade hal-lucination scale-revised (LSHS-R; Bentall & Slade, 1985) – a com-mon measure of predisposition to hallucinations – show aspecific difficulty with intentional inhibition (Paulik, Badcock, &Maybery, 2007) similar to that observed in patients with schizo-phrenia (Waters, Badcock, Maybery, & Michie, 2003b). It has beensuggested that what may differ between these groups of individu-als with AH is how they cope with, or interpret the experience(Escher, Romme, Buiks, Delespaul, & van Os, 2002; Morrison,2005). Others, however, have noted significant differences in thecharacteristic features of AH in schizophrenia and non-schizophre-nia populations, especially in terms of the frequency, valence andcomplexity of the experience (Choong, Hunter, & Woodruff,2007). These findings suggest that there may also be some impor-tant differences in the underlying cognitive mechanisms of AH,hence our model, based on deficits in context memory bindingand intentional inhibition may not apply to non-patient voicehearers.

The aim of the current study was to investigate whether healthyindividuals predisposed to AH have difficulties with contextbinding similar to that described in patients with AH (Bentall,1990; Brebion, Gorman, Amador, Malaspina, & Sharif, 2002; Seal,Aleman, & McGuire, 2004; Waters, Badcock, & Maybery, 2006b;

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Table 1LSHS-R group means, standard errors (SEs), and t-tests for the age, WASI, O-LIFE-introvertive anhedonia, and DASS-21 data

Low LSHS-R (n = 27) High LSHS-R (n = 25) t

Mean SE Mean SE

LSHS-R 5.33 .50 29.08 .79 25.85*

AGE (years) 18.74 0.59 17.80 .17 1.49WASI 111.30 1.79 115.24 1.81 1.55

Introvertive anhedonia 1.88 .42 2.92 .36 1.88DASS Anxiety 3.93 .94 11.60 1.83 3.73*

Depression 2.08 .28 13.64 1.28 8.81*

Stress 6.83 .78 20.09 1.27 8.89*

* p < .05.

Fig. 1. Configuration of the memory-binding task illustrating the sequence ofevents from study (S1 & S2) to the presentation of the recognition probe (P):different fill patterns represent different voices and separate loudspeakers repre-sent the different locations.

J.C. Badcock et al. / Personality and Individual Differences 45 (2008) 822–827 823

Waters, Maybery, Badcock, & Michie, 2004; Woodward, Menon, &Whitman, 2007). Many of these studies report a difficulty recallingthe source (i.e., ‘who’-self versus other) of spoken words and sug-gest that AH are associated with a bias in attributing self-generatedwords to an external source. However, the design of these studieshas recently been criticised, since self-generated words involveboth internal and external qualities (LarØi & Woodward, 2007),thus confounding the context memory cues involved (i.e., voiceand location). In addition, recent evidence suggests that AHs maybe associated with impaired context memory for multiple externalsources (Woodward et al., 2007), which points to a more encom-passing deficit in context binding (Waters et al., 2006a).

In the current study, we used a variant of a voice–location bind-ing task designed to assess binding in context memory. This taskexamines binding of contextual information from two externalsources (voices and locations) and therefore avoids the criticismspreviously outlined by LarØi and Woodward (2007). Importantly,the design of this task also allows context binding to be assessedwhilst minimizing the need to inhibit a response (see Section 2)which might lead to differences between high and low hallucina-tion predisposed groups. We reasoned that if high LSHS-R scorersexhibited impaired binding of voice and location information forauditory stimuli (words) compared to individuals with low LSHS-R scores, this would support the continuum model. Alternatively,should no difference in binding be observed, it would point to qual-itative differences between patient and non-patient hallucinators.We also examined the frequency of AH in healthy individuals pre-disposed to hallucinations. Since the LSHS-R assesses a wide rangeof hallucinatory experiences (including visual as well as auditoryevents) this additional assessment of the frequency of AH allowedus to explore whether impaired context binding is associated witheither a higher general predisposition to hallucinate or, more spe-cifically, with more frequent AH experiences. Finally we also exam-ined individual differences in intelligence, emotional response(depression, anxiety and stress) and negative schizotypal experi-ences in order to check the specificity of any significant results.

2. Method

2.1. Participants

Six hundred and fifteen undergraduates completed a modifiedLaunay–Slade hallucination scale-revised (LSHS-R) questionnaire(Bentall & Slade, 1985) comprising the standard 12-item scale plus3 additional questions examining the frequency of AH-like experi-ences (see Section 2.2.3). Individuals with high and low scores onthe standard LSHS-R (from the upper and lower quintiles of thedistribution) were invited to take part in the memory bindingstudy. Twenty-five high scorers (16 females) and 27 low scorers(22 females) responded to this invitation and completed the study(see Table 1).

2.2. Memory-binding task (Maybery et al., 2007)

This task assesses individual differences in the ability to bindtogether two auditory contextual features (speaker voice and loca-tion) of spoken words. On each trial participants heard a singleword spoken by two different voices in sequence, emanating fromtwo different loudspeaker locations, followed by a visual recogni-tion cue – ‘‘VOICE” or ‘‘LOCATION” – in concert with an auditorymask (see Fig. 1). A single spoken word from a single location (arecognition probe) was then presented. The participants’ taskwas to judge if the probe was the same as one of the two studyitems (yes/no response) with respect to the auditory feature –voice identity or loudspeaker location – indicated by the visual cue.

The two study items will be represented as V1L1 and V2L2

(where V and L denote the voice and location features, and the sub-scripts denote the features for the 1st and 2nd study items). Fiveprobe types were employed for each of the two recognition cues.The two critical probe types were designated ‘‘intact” and ‘‘recom-bined” probes. Intact probes were identical to a study stimulus,consisting of a word spoken in the same voice and presented fromthe same location as in the study phase (i.e., V1L1 or V2L2), whereasrecombined probes consisted of a word spoken in the voice of onestudy item but emanating from the location of the other study item(i.e., V1L2 or V2L1). Binding of voice and location features to form anintegrated representation in memory, results in faster and moreaccurate responses to intact probes relative to recombined probes(Maybery et al., 2007). Consequently, binding ability was examinedin the current study by comparing responses to these two probes;impaired binding will result in a reduced advantage for intact com-pared to recombined probes. Importantly, both critical probe typesuse ‘old’ voice and location features (i.e., features present in thestudy items) and require a positive or ‘‘yes” response; thus neitherprobe type requires inhibiting a response to a new source or inhib-iting a response to an old but currently irrelevant contextual fea-ture within a stimulus pair. Consequently individual differencesin inhibitory ability – which may be expected to vary between highand low LSHS-R groups – are experimentally controlled within thecurrent design.

Three additional recognition probes introduced either a newvoice (e.g., V3L1 or V3L2), new location (e.g., V1L3 or V2L3), orboth (e.g., V3L3 or V3L3). These probe types were included to keep

Table 2The percentages of healthy young adults reporting the various frequencies ofhallucinatory experiences

Frequency ofhallucinatory

Entiresample*

Low LSHS-R(n = 27)

High LSHS-R(n = 25)

Never 34.20 88.90 0Only once before 28.66 11.11 20Once a year 24.43 0 48Once every 3–6 months 10.42 0 20Monthly 2.12 0 8Weekly 0.16 0 4Daily 0 0 0

* Frequency data for one participant from the entire sample was missing.

824 J.C. Badcock et al. / Personality and Individual Differences 45 (2008) 822–827

participants honest in their judgments by forcing them to refer tothe cued feature in making recognition judgments. For each recog-nition judgment (voice or location), two of the additional probesrequired a negative (i.e., ‘‘no”) response (60% of all trials requireda ‘‘yes” response).

2.2.1. StimuliThe stimuli included 64 digitally-recorded spoken words, de-

rived from Taylor (2005). They comprised eight five-syllable words(consideration, discolouration, elaboration, elimination, humilia-tion, impersonation, justification, representative), spoken in eightdifferent Australian native English voices (half male). Stimuli were1000 ms in duration and presented at 58 dB. A white-noise stimu-lus, presented at the same sound pressure level, was used as theauditory mask.

2.2.2. ProcedureTesting was carried out in a sound-proof, darkened room and

began with detailed instructions emphasizing fast but accurateresponding. Stimulus presentation was controlled using a 400 HzEdsys PC fitted with a Sound Blaster 16 card. Auditory stimuli werepresented via eight Yamaha 10-watt YST M20DSP loudspeakerswhich were arranged in azimuth in front of the participant witheven spacing (36� separation of adjacent loudspeakers), and at aradius of 1.2 m around the seated participant. There were 10 prac-tice and 100 test trials, with the stimuli for these trials selectedanew for each participant of one LSHS-R group, and the same stim-ulus set used for a randomly selected participant of the other LSHS-R group. The voice and location features for the study items wereselected randomly, as were any new features required for recogni-tion probes. A single word was used on each trial, which was alsoselected at random, with different words used on consecutive tri-als. Each of the five probe types for each recognition cue (voice/location) occurred once every 10 trials, with the order of these10 trials randomized, yielding a total of 20 responses for each ofthe 5 probe types. Each trial began with a 1000 ms visual warningsignal (‘‘READY”), followed by the two study items in sequence,then the visual recognition cue and auditory mask, and finallythe auditory recognition probe. A stimulus onset asynchrony of1500 ms was used to separate all consecutive stimulus events. Rec-ognition responses were collected using a button box; reactiontime (RT) was calculated from the onset of the recognition probe.The next trial began 2000 ms after the participant’s response, or9000 ms after onset of the recognition probe if no response hadbeen made in that period. Overall task duration was approximately30 min.

2.2.3. Additional measuresThe 12 item LSHS-R (Bentall & Slade, 1985) assesses a range of

visual and auditory experiences, rated on a 5-point scale (0 = cer-tainly does not apply to me, 4 = certainly does apply to me). Thewording of LSHS-R items varies (e.g., ‘always’, ‘sometimes’, ‘onoccasions’) thus high scores may represent participants endorsinga range of hallucinatory experiences that have been present but,nonetheless, occurred relatively infrequently. Consequently, threeadditional questions were also provided to directly assess the fre-quency with which hallucinatory-type experiences occur. Thesequestions were generated based on previous factor analysis ofthe LSHS-R (Waters et al., 2003a). Specifically, the item with thehighest factor loading for each of the three factors extracted wasused to assess the frequency of hallucinatory experiences1; these

1 The three items used to assess frequency were: (1) the sounds I hear in mydaydreams are usually clear and distinct; (2) in the past, I have had the experience ofhearing a person’s voice and then found that no one was there; and (3) in the past Ihave heard the voice of God speaking to me.

three items specifically assess auditory hallucination-like experi-ences. The three frequency questions were rated on a 7 point scale(0 = I have never had this experience, 6 = daily; see Table 2). IQwas estimated using the vocabulary and matrix reasoning subtestsfrom the Wechsler Abbreviated Scale of Intelligence (WASI; Wechsler,1999). The short (21-item) version of the Depression Anxiety StressScales (DASS-21; Lovibond & Lovibond, 1995) was used to assessthe presence of enduring symptoms of depression, anxiety, andstress in a typical week. The Oxford-Liverpool Inventory of Feelingsand Experiences (O-LIFE; Mason, Linney, & Claridge, 2005) assessedschizotypal personality traits that closely correspond to negativeschizophrenic symptomatology (Introverted Anhedonia score range0–10).

The study was approved by the University of Western AustraliaHuman Research Ethics Committee and written informed consentwas obtained from each participant prior to testing. Participantswere tested individually and offered course credit points or $15reimbursement for time and expenses.

3. Results

Preliminary analyses indicated that all scores were normallydistributed. Extreme scores (>3 SDs away from respective groupmeans) were excluded (5 data points), however, analyses showedthat inclusion of outliers had no effect on the outcomes reportedbelow. Where tests for homogeneity of variance were significant,outcomes are reported for analysis of variance (ANOVA) conductedwithout the assumption of equal variances. No multivariate outli-ers were detected. An alpha level of .05 was used throughout.

3.1. Descriptive statistics

A summary of demographic, cognitive, schizotypy and emotionmeasures for the high and low LSHS-R group is presented in Table1. Substantial group separation was obtained on the LSHS-R as ex-pected. The high and low LSHS-R groups did not significantly differin age or in scores from the WASI or the O-LIFE (introvertive anhe-donia) subscale. However, the high LSHS-R group obtained signifi-cantly higher scores than the low LSHS-R group on all three DASSsubscales – Anxiety, Depression, and Stress. Thus, to account forthese differences, a DASS-Anxiety factor was formed by dividingthe entire sample into those scoring above the median (six) andthose scoring at or below the median. This factor was then in-cluded along with LSHS-R group in all analyses. These analyseswere repeated using a median split on either DASS-Depression orDASS-Stress instead of DASS-Anxiety.2 For brevity these analysesare not reported since the outcomes were consistent with thoseof the analysis based on the DASS-Anxiety factor.

2 As a further check, the main analyses were repeated using DASS-Anxiety, DASS-Depression, and DASS-Stress as covariates, revealing no change in outcome.

J.C. Badcock et al. / Personality and Individual Differences 45 (2008) 822–827 825

3.2. Frequency of hallucinations

The data were screened for internal consistency on an item-by-item basis to ensure that participants who reported a low LSHS-Rscore (i.e., ‘‘certainly does not apply to me”) reported a consistentresponse on the frequency items (i.e., ‘‘I have never had this expe-rience”, rather than ‘‘I experience this daily”), and that similar con-sistency applied for participants reporting a high LSHS-R score(they should not report ‘‘I have never had this experience”). Noinconsistency between responses to the LSHS-R and frequencyquestions was evident. The mean of responses to the three fre-quency questions was calculated to provide a summary index ofthe frequency of hallucinations (mean scores were rounded downto the nearest whole number in order to preserve the scale). Table2 summarizes the percentage of individuals reporting the variousfrequencies of hallucinatory experiences, based on this summaryindex, for the entire sample of undergraduate students initiallytested, and separately for the high and low LSHS-R subgroups.The specific AH-like experiences assessed occurred infrequently,even in individuals in the high LSHS-R group.

3.3. Memory-binding task

The percentage of correct responses (accuracy) and median RTsfor correct responses, for the different trial types was calculated foreach participant (see Table 3). The central analyses focused on

Table 3Descriptive statistics for accuracy (percent correct) and RT (ms) as a function of probetype

Low LSHS-R High LSHS-R

Mean SE Mean SE

AccuracyIntact 98.33 .53 98.60 .61Recombined 92.59 1.08 93.60 1.10Old (new) 92.96 1.29 91.20 1.39New (old) 92.04 1.37 90.40 1.29New (new) 93.33 1.31 91.40 1.65

RTIntact 1040.71 38.77 1023.53 44.59Recombined 1149.36 40.06 1133.34 41.83Old (new) 1180.92 43.73 1198.20 48.19New (old) 1134.31 41.71 1076.67 38.13New (new) 1127.81 43.24 1097.86 49.14

The old/new status of the two features of the probe is shown for the cued featurefollowed by the uncued feature (in parentheses); for example, old (new) refers tousing an old value for the cued feature and a new value for the uncued feature.

Low LSHS-R High LSHS-R

70

80

90

100

Intact Recombined Intact Recombined

Probe Type

Acc

ura

cy (

%)

Fig. 2. Mean accuracy and RT (and 95% confidence intervals) for both

comparing the intact and recombined probes since these addressbinding ability. A 2 (LSHS-R group: high, low) � 2 (DASS-Anxietygroup: high, low) � 2 (recognition probe: intact, recombined) � 2(recognition cue: voice, location) mixed-design ANOVA was con-ducted for each dependent variable, where the last two factorswere repeated-measures.

3.3.1. AccuracyAccuracy for the two critical recognition probes for both high

and low LSHS-R groups is displayed in Fig. 2. Analysis revealed asignificant main effect of probe type, with higher accuracy for in-tact (M = 98.76%, SE = .42%), compared to recombined probes(M = 93.29%, SE = .96%), F(1,46) = 28.95, p < .05, partial-g2 = 0.39.However, none of the other main effects or interactions was signif-icant. The absence of significant interactions with probe type indi-cates comparable memory binding for the two LSHS-R groups andfor the two DASS-Anxiety groups.

3.3.2. Reaction time (RT)RT for the two critical recognition probes for both LSHS-R

groups is also displayed in Fig. 2. Consistent with the outcomesfor accuracy, participants were faster at responding to intact(M = 1045.14 ms, SE = 35.89 ms), compared to recombined(M = 1146.89 ms, SE = 35.62 ms) probes, F(1,46) = 28.92, p < .05,partial-g2 = 0.39. However, all the other main effects and interac-tions were non-significant. Again the absence of significant effectsinvolving either LSHS-R group or DASS-Anxiety group indicatescomparable memory binding for the two LSHS-R groups and forthe two DASS-Anxiety groups.

3.4. Correlations between the frequency of hallucinations and bindingability

In order to examine if impaired binding was associated withmore frequent AH in the high LSHS-R subgroup, the summary in-dex of AH frequency was correlated with two indices of bindingability derived from the context memory task. These indices werecalculated by subtracting mean RT (or mean accuracy) for intactprobes from the mean RT (or mean accuracy) for recombinedprobes. The results showed that frequency of AH experiences wasnot significantly correlated with either measure of binding ability:accuracy, r(25) = .20, p > .05; RT, r(25) = �.10, p > .05. Similarly,there was no significant correlation between these measures ofbinding ability and scores on the standard LSHS-R reflecting in-creased predisposition to hallucinations in general: accuracy,r(25) = .12, p > .05; RT, r(25) = .01, p > .05.

Low LSHS-R High LSHS-R

600

800

1000

1200

Intact Intact Recombined Recombined

Probe type

Rea

ctio

n t

ime

(ms)

high and low LSHS-R groups for the critical recognition probes.

826 J.C. Badcock et al. / Personality and Individual Differences 45 (2008) 822–827

4. Discussion

This study utilized a voice–location binding task, entailing twoexternal sources, to examine context binding in individuals predis-posed to hallucinations. The main findings of the study show thatthe integration of voice and location features in context memory isintact in healthy young adults predisposed to hallucinations ingeneral and, in particular, that context binding deficits are notassociated with more frequent AH experiences.

The current findings emphasize that the phenomenology of hal-lucinatory experiences – at least in terms of frequency – is mark-edly different in healthy individuals predisposed to hallucinationscompared to that reported in patients with schizophrenia. Approx-imately 75% of individuals with psychosis have been reported toexperience AH at least once a day (Steel et al., 2007). Predispositionto hallucinatory experiences in healthy individuals is commonly as-sessed using the LSHS-R (Bentall & Slade, 1985). High scores on thisscale may be achieved by endorsing a wide range of experiences –including visual and auditory hallucinations which may occur ‘of-ten’, ‘sometimes’ or ‘on occasion’. However, when asked specificallyto report the frequency of three LSHS-R items which focus on AH-like experiences only 32% of the high LSHS-R subgroup reportedexperiencing these as occurring at least once every 3–6 monthsand the modal frequency was only ‘once a year’. Analogue samples(e.g., of undergraduate students assessed with schizotypy mea-sures) are frequently used with the intention of examining cogni-tive and/or biological mechanisms relevant to symptoms ofschizophrenia whilst avoiding potential confounds related to theeffects of medication or hospitalization. The current data suggestthat more caution may be needed when assuming continuity ofexperiences – and underlying mechanisms – between patient andnon-patient hallucinators.

The present data also indicate that there is no evidence of im-paired context binding ability in healthy young adults who arehighly predisposed to hallucinations. Events in episodic memoryare usually encoded as an integrated representation together withrelevant contextual details. Consequently intact recognition probestypically yield responses which are faster/more accurate thanrecombined probes. Indeed, such an advantage was found in thepresent study, consistent with previous findings (Maybery et al.,2007). Importantly, the high level of accuracy for intact probesdid not limit the sensitivity of the task; the difference in perfor-mance for intact and recombined probes was of medium size (par-tial-g2 = 0.39 for each dependent variable), consisting of adifference in accuracy of 5.47% and a difference in RT of101.75 ms. Impaired memory binding should have resulted in a re-duced advantage for intact compared to recombined probes in thehigh LSHS-R group; however, there was no evidence of impairedbinding of auditory context (voice or location) in the current data.Furthermore, we tested whether there was a correlation betweencontext binding ability and the frequency of AHs in the highLSHS-R subgroup: this association was also non-significant. Overallthese results diverge from recent studies revealing context bindingimpairments in patients with schizophrenia (Seal et al., 2004;Waters et al., 2004; Woodward et al., 2007).

These findings raise some interesting possibilities. First, halluci-nations in patient and non-patient (healthy) groups may be sub-served by some common (e.g., intentional inhibition) and somepartially distinct (e.g., memory binding) mechanisms. For example,Paulik et al. (2007) have shown a pattern of impaired intentionalinhibition for high LSHS-R scorers (relative to low LSHS-R scorers)which matches the pattern exhibited by schizophrenia patientswith AH (Waters et al., 2003b). That outcome is important sinceit shows that the current design (comparing high and low LSHS-R groups) is potentially sensitive to cognitive differences, yet dif-

ferences in context binding ability could not be detected. Clearlya related possibility is that context memory binding deficits mayonly emerge as psychosis fully develops (Dore, Caza, Gingras, &Rouleau, 2007).

Secondly, the current memory binding task entails automaticencoding of context. In contrast, many studies in psychotic patientswith hallucinations, which have shown memory binding deficits,have employed tasks favouring intentional encoding of context(Dore et al., 2007; Waters et al.,2006a, 2006b). There are now sev-eral studies suggesting that intentional cognitive processing is con-sistently impaired in schizophrenia whilst automatic processing isoften spared (e.g., Racsmany et al., 2008). Thus, it is possible thatmemory binding difficulties in individuals predisposed to halluci-nations may be revealed when intentional binding is assessed.We are currently investigating this issue in our laboratory.

Finally, we have previously shown that schizophrenia patientswith current AH exhibit a combination of deficits in context bind-ing and intentional inhibition. The current findings raise the possi-bility that this model may not be appropriate for healthyindividuals predisposed to hallucinations or may require modifica-tion to clarify that memory binding deficits are specifically inten-tional in nature. Furthermore, the increased need for care inschizophrenia patients with hallucinations may be due to the par-ticular cognitive consequences arising from context memorydifficulties. However, it must be noted that in order to determinewhether context binding deficits do not occur on a continuum withpatients with schizophrenia it would be necessary for futurestudies to employ precisely the same voice–location binding taskused in the current study to assess schizophrenia patients withAH. More generally, the current findings strongly suggest that amore systematic investigation of different forms of context bind-ing linked to AH both in patient and non-patient groups iswarranted.

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