www.elsevier.com/locate/schres

Schizophrenia Research

Sustained attention deficits in relation to psychometrically

identified schizotypy: Evaluating a potential

endophenotypic marker

Diane C. Gooding a,b,*, Christie W. Matts a, Elizabeth A. Rollmann a,c

a University of Wisconsin-Madison, Department of Psychology, United Statesb University of Wisconsin-Madison, Department of Psychiatry, United States

c Mayo Clinic College of Medicine, Rochester, Minnesota, United States

Received 28 September 2005; received in revised form 21 November 2005; accepted 23 November 2005

Abstract

Sustained attention deficits have been posited as a potential endophenotypic marker of vulnerability to schizophrenia. Prior

studies have indicated that schizophrenia patients, their first-degree relatives, and psychosis-prone individuals, identified on the

basis of measures of positive schizotypy, have demonstrated sustained attention deficits. To date, there have been no published

reports of sustained attention deficits in individuals with negative schizotypy, as measured by the revised Social Anhedonia

Scale. In this study, we examined sustained attention, measured with the CPT-Identical Pairs version, in 160 individuals with

elevated scores on the Chapman Perceptual Aberration and/or Magical Ideation Scales, 96 individuals with elevated scales on

the Social Anhedonia Scale, and 137 controls. Both psychosis-prone groups performed more poorly than the controls in terms

of discrimination ability, as measured by dV, though the groups did not differ in terms of either their reaction time or overall

response criterion (lnb). These results provide evidence that both positive and negative aspects of schizotypy are associated

with sustained attention deficits, as measured by the Continuous Performance Test. The findings add to the converging evidence

indicating that sustained attention deficits are a potential endophenotypic indicator of a schizophrenia diathesis.

D 2005 Elsevier B.V. All rights reserved.

Keywords: Schizotypy; Attention; Endophenotype; Continuous performance test

0920-9964/$ - see front matter D 2005 Elsevier B.V. All rights reserved.

doi:10.1016/j.schres.2005.11.015

* Corresponding author. Department of Psychology, 1202 W.

Johnson Street, Madison, WI 53706, United States. Tel.: +1 608 262

3918 (O); fax: +1 608 262 4029.

E-mail address: dgooding@facstaff.wisc.edu (D.C. Gooding).

1. Introduction

Continuous performance tasks (CPTs) are one of

the most frequently used measures of sustained

attention in experimental psychopathology research.

There are several variants of CPTs, all of which assess

the ability to discriminate targets from nontargets.

82 (2006) 27–37

D.C. Gooding et al. / Schizophrenia Research 82 (2006) 27–3728

However, the versions differ in terms of their level of

difficulty and the extent to which their psychometric

properties have been investigated. One of the most

widely used versions is the CPT-Identical Pairs

version (CPT-IP; Cornblatt et al., 1988) which

requires participants to respond as quickly as possible

to any consecutive presentation of identical stimuli.

1.1. Sustained attention deficits in schizophrenia

patients

Schizophrenia patients have consistently displayed

deficits on the CPT-IP, such as lower ability to

discriminate targets from nontargets, called discrimi-

nation sensitivity or dV (Cornblatt et al., 1989a,b, 1997;Franke et al., 1994; Laurent et al., 1999), and a higher

rate of random errors (Cornblatt et al., 1989a,b; Franke

et al., 1994; Laurent et al., 1999). This CPT deficit is

independent of clinical state and not an epiphenome-

non of chronicity, illness severity, or hospitalization

status (Michie et al., 2000; Cornblatt and Malhotra,

2001). Moreover, schizophrenia patients’ CPT deficits

do not normalize with medication (Cornblatt and Keilp,

1994; Cornblatt et al., 1997; Michie et al., 2000). As

such, sustained attentional deficits have been posited

as an endophenotypic indicator of liability to schizo-

phrenia (Chen and Faraone, 2000; Cornblatt and Keilp,

1994; Cornblatt and Malhotra, 2001; Gottesman and

Gould, 2003). That is, the CPT deficits observed in

schizophrenia patients may represent a more funda-

mental disturbance that might predate the onset of

manifest psychosis. Using CPT deficits as an endo-

phenotype of schizophrenia would be useful in terms of

enhancing our understanding of the underlying patho-

physiology of the disorder, as well as providing a more

proximal indicator of vulnerability to the disorder.

1.2. Sustained attention deficits as a neurocognitive

risk factor for schizophrenia

If CPT deficits are an endophenotype of schizo-

phrenia, then these deficits are expected to precede the

manifestation of the disorder in vulnerable individu-

als. Studies of individuals at risk for schizophrenia are

advantageous because they avoid potential confounds

of medication status, chronicity, and florid psychosis.

One major research strategy used to identify individ-

uals at heightened risk for schizophrenia is the genetic

high-risk strategy. This approach studies individuals

who are genetically related to an affected schizophre-

nia proband. Investigations using the CPT-IP have

indicated that asymptomatic first-degree relatives of

schizophrenia probands show poorer processing

capacity (lower dV; Cornblatt and Keilp, 1994; Franke

et al., 1994; Laurent et al., 1999) and a higher

likelihood to respond to irrelevant stimuli (random

responses; Franke et al., 1994). Furthermore, in

adolescents at genetic risk for schizophrenia, these

attentional deficits remain stable over time despite a

significant increase in behavioral disturbances (Corn-

blatt et al., 1989a,b; Winters et al., 1991). Thus,

investigations of CPT-IP performance in genetically

at-risk individuals support the notion of sustained

attention deficits as a neurocognitive risk factor for

schizophrenia. Another research strategy for identify-

ing vulnerable individuals is to study populations who

are at heightened clinical risk for the later develop-

ment of schizophrenia, such as patients with schizo-

typal personality disorder. Patients with schizotypal

personality disorder display a pattern of sustained

attention deficits (cf. Lees Roitman et al., 1997) that is

similar to, but less severe than, the pattern that

characterizes schizophrenia patients.

The psychometric high-risk method provides an-

other research strategy to identify individuals at risk

for schizophrenia. In this approach, investigators

identify at-risk individuals based on their psychomet-

ric profiles. Some, if not all, of these hypothetically

psychosis-prone individuals possess schizotypy, a

personality organization associated with an underlying

diathesis for the later development of schizophrenia

(Meehl, 1962, 1989, 1990). Guided by Meehl’s

seminal (1962, 1990) model, we assume that schizo-

typy and schizophrenia lie on a continuum of

pathology and share a common neurobiological

substrate. As such, we expect that individuals endors-

ing schizotypal traits would perform more similarly to

schizophrenia patients than to normal controls.

There have been relatively fewer investigations of

CPT-IP performance in schizotypic individuals identi-

fied by the psychometric high-risk method. To date,

nearly all of the published reports using the CPT-IP and

the psychometric high-risk method have focused on

measures of positive schizotypy. Two measures of

positive schizotypy are the Perceptual Aberration Scale

(Chapman et al., 1978) and the Magical Ideation Scale

D.C. Gooding et al. / Schizophrenia Research 82 (2006) 27–37 29

(Eckblad and Chapman, 1983). There is an extensive

literature regarding the reliability and validity of the

Perceptual Aberration Scale, either alone, or in combi-

nation with the Magical Ideation scale, as an indicator

of schizotypy (cf. Chapman et al., 1995, 1994;

Lenzenweger et al., 2003).

College undergraduates screened using the Percep-

tual Aberration Scale display significantly poorer

performance on the CPT-IP (Lenzenweger et al.,

1991) than controls. The psychometrically identified

schizotypes displayed lower dV indices, although they

did not differ from the normal controls in terms of

proportion of false alarms. In another, smaller sample

of schizotypic individuals identified using the Percep-

tual Aberration Scale, Lenzenweger (2001) observed

that the schizotypic individuals displayed slower

reaction time than the controls on the CPT-IP. Among

an army recruit population (Obiols et al., 1993)

screened using the Perceptual Aberration Scale in

conjunction with another schizotypy scale (the STA;

Claridge and Broks, 1984), individuals identified as

schizotypal showed lower sensitivity and made fewer

correct responses (dhitsT).To date, there has been scant research attention to

whether there might be an association between

sustained attention performance deficits and negative

schizotypy.1 However, several cross-sectional studies

(cf. Gooding and Braun, 2004; Gooding et al., 1999,

2001; Gooding and Tallent, 2003; Luh and Gooding,

1999; Tallent and Gooding, 2000; Tsakanikos, 2004)

suggest that individuals reporting excessive levels of

social anhedonia may also display neurocognitive

performance deficits similar to those seen in schizo-

phrenia patients, albeit more subtle in magnitude.

Furthermore, longitudinal studies demonstrate that at-

risk individuals, identified on the basis of their

elevated scores on the Social Anhedonia Scale, are

at heightened risk for the later development of

schizophrenia-spectrum disorders (Gooding et al.,

1 Using a behavioral high-risk approach, Obiols et al. (1997)

screened for schizotypal adolescents using CPT-IP performance.

Individuals with attentional deficits, as measured by the CPT, had

significantly higher scores on the Social Anhedonia Scale than those

with normal CPT performance. They also noted a trend whereby

participants in the lowest decile of performance had higher scores

on the Perceptual Aberration Scale than those participants with

better CPT performance.

2005; Kwapil, 1998). Based on prior research, it is

plausible to predict that individuals with deviantly

high scores on the Social Anhedonia scale would

display significantly poorer attentional performance

on the CPT than normal controls.

1.3. The present study

The aim of the present study is to investigate

whether psychosis-prone and schizotypic young adults

demonstrate sustained attention deficits consistent

with those reported in patients with schizophrenia as

well as individuals at genetic and clinical risk for

schizophrenia. Specifically, we sought to replicate

prior work examining the CPT performance of

individuals exhibiting positive schizotypy. We ex-

pected that individuals exhibiting positive schizotypy

would display subtle sustained attention deficits. To

our knowledge, there are no published studies exam-

ining CPT performance in schizotypal individuals

characterized by negative schizotypy. Thus, we were

particularly interested in extending the extant literature

in this regard. We anticipated that individuals with

negative schizotypy, i.e., individuals with deviant

Social Anhedonia Scale scores, would display sus-

tained attention performance patterns similar to those

observed in schizophrenia patients. A secondary aim

of the investigation was to compare the CPT perfor-

mance of individuals with negative schizotypy to that

of individuals with positive schizotypy. Because

positive schizotypy is associated with the later

development of psychotic disorders in general (Chap-

man et al., 1994), whereas elevated social anhedonia is

associated with increased specific risk for schizophre-

nia-spectrum disorders, we predicted that the individ-

ual with deviant Social Anhedonia Scale scores

might display greater deficits on the CPT than the

other psychometrically identified at-risk group.

2. Methods

2.1. Selection procedure

The high-risk and control participants were drawn

from a sample of 2839 male and 3545 female

undergraduate students who were screened over four

consecutive semesters using a 179-item true–false

D.C. Gooding et al. / Schizophrenia Research 82 (2006) 27–3730

self-report questionnaire called the bSurvey of Atti-

tudes and ExperiencesQ. This questionnaire is a ran-

dom mixture of items from the Chapman Psychosis-

proneness scales, namely, Perceptual Aberration,

Magical Ideation, revised Physical Anhedonia, and

revised Social Anhedonia scales (Chapman et al.,

1976, 1978; Eckblad and Chapman, 1983; Eckblad et

al., 1982) as well as the Chapman Infrequency Scale

(Chapman and Chapman, 1983).

There were two groups of at-risk subjects, namely,

the Per-Mag group and the Soc Anh group. The Per-

Mag group consisted of individuals who endorsed an

excessively high number of deviant items (at or

beyond 2 S.D. values from the same-sex sample

mean) either on the Perceptual Aberration and/or

Magical Ideation scales (the Per-Mag group). An

example of an item on the Perceptual Aberration scale

is bParts of my body occasionally seem dead or

unrealQ (keyed true). An example of an item on the

Magical Ideation scale is bGood luck charms don’t

workQ (keyed false). The SocAnh group consisted of

individuals who endorsed an excessively high number

of deviant items (at or beyond 2 S.D. values from the

same-sex sample mean) on the revised Social Anhe-

donia scale. The revised Social Anhedonia scale

includes items such as bI sometimes become deeply

attached to people I spend a lot of time withQ (keyedfalse). The controls were individuals who received

gender-normed standardized scores of less than 0.5

S.D. on all of the Chapman scales.

2.2. Participants

Following psychometric screening, participants

were invited to participate in a multiple-session study

of bindividual differences and brain functioningQ. Fourhundred and fifty-eight individuals were tested after

giving their informed consent. As part of the

assessment, participants were screened for a history

of learning disabilities, epilepsy, or traumatic brain

injury. Participants were also screened for personal

history of psychotic illness and/or any psychoactive

substance use disorder. In addition, all participants

were right-handed, free of any current or past mood

disorder, free of attention deficit hyperactivity disor-

der, and had normal or corrected to normal vision.

Control subjects were also screened to exclude those

individuals who had a family history of psychotic

illness. The resultant sample consisted of three

hundred and ninety-eight undergraduates.

2.3. Continuous Performance Test—Identical Pairs

Version (CPT-IP)

Sustained attention was measured using the Con-

tinuous Performance Test—Identical Pairs Version

developed by Cornblatt et al. (1988, 1989a,b). The

CPT-IP version was chosen due to its increased

demand on working memory, and hence, increased

difficulty (cf. Borgaro et al., 2003; Chen and Faraone,

2000; Michie et al., 2000).

The CPT-IP is a high processing load version of the

continuous performance task paradigm. During the

CPT-IP, stimuli are visually presented in relatively

rapid succession, and participants are required to

respond when the same stimulus appears twice in a

row (i.e., an identical pair). In this computerized

attention task, there are two subtasks, which are

matched in difficulty: the digit subtask and the shapes

subtask. In the digits subtask, a series of four digit

stimuli are presented on a computer screen. In the

shapes subtask, a series of four nonsense shapes are

presented. The nonsense shapes are complex patterns

that were specifically designed to resist verbal

labeling. These two types of stimuli are either

presented with or without visual distraction, which

consisted of bright asterisks surrounding the target

stimulus, rendering it more difficult to read and

disambiguate the target stimuli. Numbers and shapes

were presented in separate conditions. Thus, the four

conditions administered included: digit strings

(Numbers Task); shapes (Shapes); digit strings in the

presence of visual distraction (Numbers with Distrac-

tion); and shapes presented in the presence of visual

distraction (Shapes with Distraction). For all four

conditions, the stimuli are presented at the rate of 1/s,

and the stimulus duration was 50 ms, with an ITI of

950 ms.

The tasks were administered on computers

equipped with a mouse so that the participants could

respond with a finger lift connected to a reaction time

key. Participants were instructed to respond as fast as

possible. The task was made more difficult by

including not only target trials but also including

catch trials. In the catch trials, the stimuli are similar

but not identical, e.g., in the numbers condition, the

D.C. Gooding et al. / Schizophrenia Research 82 (2006) 27–37 31

consecutive four digit numbers differed by one digit

only. After a practice session, in which participants

were given feedback for correct and incorrect

responses, the tasks were administered. Participants

did not have information regarding the proportions of

the trials. A total of 600 trials, 20% of them targets

and 20% of them catch trials, were divided into four

successive blocks. The remaining trials were filler

trials in which the stimuli presented were dissimilar

from the stimuli that immediately preceded them.

The CPT was scored using the program provided

(Biobehavioral Technologies, Inc., 1997). Correct

responses, responses made to the second of two

identical stimuli presented in a row, were scored as

hits. Errors of commission in which responses were

made to the catch trials were scored as false alarms.

Performance on the CPT was scored in terms of:

proportion of hits, reaction time (in ms) of hits, and

proportion of false alarms, as well as two signal

detection indices.2 The two signal detection indices

were dV (the index of discrimination sensitivity),

which measures decline in sensitivity or attentional

capacity, and beta (b) (transformed to the natural log

scale, lnb), an index of response bias, or tendency to

overrespond or under-respond. Both the dV and lnbindices were computed using the hit rate and false

alarm rate data. The dV value provides an index of

sensitivity, with higher dV values indicating better

attentional performance. The lnb value reflects the

participant’s response bias, with higher values indi-

cating a more conservative response criterion.

2.4. Intellectual functioning

IQ was measured to insure that any possible group

differences on the CPT could not be attributed to

differences in intellectual ability. The Shipley–Hart-

ford (Shipley, 1939) test is a brief screening device that

consists of a vocabulary subtest and an abstraction

subtest. In the vocabulary subtest, each item consists of

a target word and four alternatives. Participants are

asked to circle the alternative word that means the

2 Our participants rarely made responses to the CPT-IP filler

stimuli; this situation was also noted in a prior study based upon a

highly educated sample (cf. Lenzenweger et al., 1991). Due to the

infrequency of their occurrence, it was not possible to analyse the

responses to CPT-IP filler stimuli, or random errors (Cornblatt et al.,

1988).

same or most nearly the same as the target word. In the

abstraction subtest, individuals are required to fill in

the numbers or letters that logically complete a given

sequence. The resultant vocabulary and abstraction

scores were converted to provide WAIS-R estimates

(cf. Bartz and Loy, 1970; Weiss and Schell, 1993);

correlations between the Shipley–Hartford scores and

Full scale Wechsler IQs are moderately high (r=0.80;

Holmstrom et al., 1993). All assessments were

conducted by research staff members who were trained

by PhD level psychologists and who were unaware of

individuals’ group status.

2.5. Statistical analysis

Following the recommended method of analysis

(Cornblatt et al., 1988,1989a,b), we performed a 3

(group: Per-Mag vs. SocAnh vs. control)�2 (stimulus:

numbers vs. shapes)�2 (distraction: absent vs. pres-

ent) repeated analysis of variance (MANOVA) for each

of our outcome variables. The primary variables of

interest were sensitivity (as measured by dV) and

response criterion (as indicated by lnb). Reaction time

data for the correct responses were also analysed. Since

deficits in asymptomatic individuals at-risk individuals

are expected to be subtle, the level of significance was

set at 0.05. Analysis of variance (ANOVA) procedures

were used to compare the three groups on age and

estimated IQ. Chi-square analyses assessed differences

in the distribution of gender among groups.

3. Results

Individuals with CPT performance profiles which

appeared indicative of random or invalid test taking, such

as extremely low hit rates (10% or less correct; n =3) and/or

nearly equal proportions of hits and false alarms (n =2) were

omitted from further study. The final sample included 160

Per-Mag subjects (59 male, 101 female), 96 SocAnh (37

male, 59 female) subjects, and 137 control (68 male, 69

female) subjects.

The groups did not differ significantly in terms of the

percentage of males, v2(2)=5.47, n.s. The mean age,

estimated full-scale IQ, and Chapman scale scores for each

group are provided in Table 1. The groups did not differ in

age, F(2,390)=1.65, n.s.; the mean age of the sample was

18.99 years. Similarly, the groups did not differ in terms of

estimated full-scale IQ, F(2,390)=0.19, n.s.

Table 1

Demographic characteristics and Chapman Scale scores

Variable Group

Per-Mag (n =160) SocAnh (n =96) Controls (n =104)

Mean S.D. Mean S.D. Mean S.D.

Age 18.81 1.05 18.88 1.07 19.04 1.21

Estimated IQ 115.34 5.12 115.72 4.77 115.55 4.75

Perceptual Aberration 16.36 6.90 8.98 6.08 3.04 2.55

Magical Ideation 20.42 3.97 11.19 5.78 5.79 2.79

Social Anhedonia 8.64 4.65 21.04 3.83 4.77 2.74

Physical Anhedonia 8.51 6.04 16.98 7.96 8.72 4.17

D.C. Gooding et al. / Schizophrenia Research 82 (2006) 27–3732

3.1. Discrimination sensitivity (dV)

Table 2 provides the mean dV scores and standard

deviations on the CPT-IP performance for each of the four

tasks in the three groups. The discrimination sensitivity

data were analyzed using a 3 (group)�2 (stimulus

type)�2 (distraction condition) repeated measuresANOVA.

There was a main effect of group, F(2,390)=9.89, p b0.001,

as well as a significant main effect of stimulus type,

Table 2

Sustained-attention performance for all three groups

Measures by condition Per-Mag (n =160)

Mean S.D.

Numbers

dV 2.08 0.78

lnb �0.06 0.71

Hits 0.82 0.14

RT hits 504.94 66.10

False alarms 0.18 0.14

Numbers with distraction

dV 2.17 0.92

lnb 0.40 0.83

Hits 0.77 0.17

RT hits 570.71 67.82

False alarms 0.14 0.14

Shapes

dV 2.14 0.81

lnb 0.35 0.84

Hits 0.79 0.14

RT hits 516.14 60.44

False alarms 0.15 0.13

Shapes with distraction

dV 2.38 0.93

lnb 0.62 0.84

Hits 0.79 0.15

RT hits 541.55 60.84

False alarms 0.11 0.14

dV is a measure of discrimination sensitivity; lnb is a measure of response b

target trials; RT hits is reaction time for the correct responses; false alarm

F(1,390)=7.16, p b0.01. However, there was no group by

stimulus interaction, F(2,390)=0.30, n.s.

Overall, the participants showed greater discrimination

sensitivity on the shapes task than on the numbers tasks.

Between groups post-hoc tests (t tests for pooled variances)

revealed that the Per-Mag group showed the least discrim-

ination sensitivity (as evidenced by the lowest dV) and the

control group showed the greatest discrimination sensitivity.

The Per-Mag group had a significantly lower mean dV score

SocAnh (n =96) Control (n =137)

Mean S.D. Mean S.D.

2.20 0.78 2.38 0.67

�0.07 0.84 �0.06 0.83

0.83 0.13 0.86 0.12

508.20 62.54 502.29 57.87

0.16 0.11 0.14 0.10

2.29 0.83 2.50 0.64

0.53 0.77 0.49 0.84

0.78 0.15 0.83 0.11

561.42 63.88 560.59 56.60

0.11 0.09 0.09 0.07

2.21 0.86 2.44 0.64

0.40 0.84 0.37 0.98

0.81 0.13 0.83 0.11

519.96 58.33 510.17 53.21

0.16 0.21 0.11 0.10

2.40 0.80 2.70 0.74

0.57 0.96 0.72 0.96

0.80 0.80 0.83 0.87

536.15 64.26 536.77 51.39

0.10 0.12 0.07 0.10

ias or decision criterion; hits is the proportion of correct responses to

s is the proportion of commission errors.

D.C. Gooding et al. / Schizophrenia Research 82 (2006) 27–37 33

than the control group, p b0.001, and the SocAnh group had a

lower d score than the control group, p b0.05. However, the

two groups of psychometrically identified at-risk individuals

did not differ significantly from each other in terms of

their ability to detect the target from non-targets on the tasks.

Within-subject comparison found a significant effect of

distraction, F(1,390)=44.56, p b0.001, as well as a signif-

icant stimulus by distraction interaction, F(1,390)=8.23,

p b0.01. Participants showed greater discrimination sensitiv-

ity on conditions involving distraction, and the distraction

condition had a greater effect on the shapes task than on the

numbers task.3 No other interactions were found.

3.2. Response criterion (lnb)

The groups’ mean lnb scores and standard deviations for

each of the four tasks are provided in Table 2. The between

factor analysis failed to yield a significant main effect of

group, F(2,390)=0.24, n.s. Within-subject comparisons

revealed a main effect of stimulus type, F(1,390)=51.29,

p b0.001 and a significant effect of distraction, F(1,390)=

160.32, p b0.001. Participants relied upon a more conserva-

tive response criterion (i.e. sacrificing correct responses to

make fewer errors), as evidenced by a larger b, for the shapesstimuli than the digits. Participants also used a more

conservative response criterion in the distraction conditions

compared to the conditions without distraction. We also

observed an interaction between stimulus type and distrac-

tion, F(2,390)=22.11, p b0.001. Participants used the most

liberal response criterion (i.e., maximizing the likelihood of

hits but making more errors) when responding to the numbers

without distraction condition and the most conservative res-

ponse criterion when responding to the shapes with distrac-

tion condition. There were no other significant interactions.

In particular, the at-risk individuals’ response criteria were

not differentially affected by any of the task conditions.

3.3. Reaction times

We also analyzed the reaction time data for hits. Fig. 1

provides a depiction of the accuracy data as well as reaction

time data for the three groups on each of the four conditions.

Using repeated measures ANOVA, we observed no signif-

3 While this result may seem counterintuitive, it is actually analo-

gous to what is frequently observed in smooth pursuit eye tracking

studies, i.e. on trials in which participants are instructed to count the

number of times the stimulus target changes appearance while

visually following it, participants’ pursuit actually improves. The

effortful mobilization ofmore resources results in greater focus on the

task; although this attention enhancement leads to better perfor-

mance, it does not normalize performance where there is a deficit.

icant between group difference in mean reaction times for

hits, F(2,390)=0.48, n.s. However, there were significant

main effects of stimulus [F(1,390)=14.55, p b0.001] and

distraction [F(1,390)=537.56, p b0.001]. Within-subject

analysis revealed a significant stimulus by distraction

interaction, F(1,390)=118.75, p b0.001. Overall, partici-

pants displayed the longest reaction time during the numbers

with distraction condition and the shortest reaction time

during the numbers without distraction condition. No other

interactions were significant.

4. Discussion

A primary goal of this study was to examine the

attentional performance of schizotypic young adults.

We were especially interested in studying individuals

with excessively high scores on the revised Social

Anhedonia Scale, because such individuals are at

heightened risk for the later development of schizo-

phrenia-spectrum disorders. We found that the ques-

tionnaire-identified schizotypes exhibited lower

discrimination sensitivity on the CPT-IP compared to

the control participants. This is the first study to

demonstrate that individuals identified based on the

Social Anhedonia Scale show sustained attention defi-

cits, as measured by the CPT-IP. Consistent with prior

investigations (Lenzenweger et al., 1991), psychosis-

prone individuals with positive schizotypy showed

significantly poorer performance than the controls.

However, in contrast to a prior report (Lenzenweger,

2001), we did not observe slowed responding among

the schizotypes. Rather, there were no between-group

differences in terms of reaction times for correct

responses, although the response latencies for all

participants varied across tasks and conditions.4

In the present study, the two groups of schizotypal

individuals did not differ from the control group in

terms of their response criterion, lnb. Thus, the three

groups did not differ in their level of motivation,

cooperativeness, or the amount of evidence that they

required prior to decidingwhether or not a stimulus was

a target. Thus, we interpret our finding of between-

4 It is noteworthy in this regard that our sample of schizotypes is

substantially larger than prior samples; it is possible that, as

Lenzenweger (2001) had opined, the observed prolonged response

latencies may have been attributable to other idiosyncratic

characteristics of that particular sample.

Fig. 1. Hit rates for the Per-Mag, SocAnh, and Control groups for the Numbers Conditions (top left) and the Shapes Conditions (top right).

Reaction time data for the Per-Mag, SocAnh and Control groups for the Numbers conditions (bottom left) and the Shapes Conditions (bottom

right) are also provided. For all four figures: NUM-ND=numbers with no distraction, NUM-D=numbers with distraction, SHAPES-

ND=shapes with no distraction and SHAPES-D=shapes with distraction.

D.C. Gooding et al. / Schizophrenia Research 82 (2006) 27–3734

group difference in terms of dV scores as evidence thatthe schizotypal participants’ performance reflects

impaired sustained attention. One strength of the study

is the fact that the three groups did not differ in overall

intellectual functioning. Because the groups were

equivalent in terms of their estimated IQ, the observed

differences in attentional performance cannot be

attributed to intellectual impairment in the psychomet-

rically identified at-risk groups. Another strength of the

present study is the inclusion of large samples of

schizotypic individuals. Thus, we had the statistical

power to detect the subtle information-processing

deficit that was present in this high-functioning,

nonclinical population.

While our hypothesis that the negative schizotypy

group (i.e., the SocAnh participants) would display

greater deficits than the positive schizotypy group was

not borne out, both groups of at-risk individuals could

be distinguished from the controls in terms of their

verbal and spatial attention on this high processing

load version of the CPT. Various cognitive processes

contribute to successful performance on the CPT-IP.

The task involves target detection, sustained attention,

and context representation or working memory. Thus,

lowered performance on the CPT-IP may be a final

common pathway for different neurocognitive mech-

anisms. The Per-Mag individuals may have performed

more poorly than the controls on the task due to an

attentional deficit that reflects deficient stimulus

evaluation and target detection as well as lowered

sustained attention, which in turn, results in poorer

working memory, while the SocAnh group may have

performed more poorly than the controls on the CPT-

IP due to less efficient monitoring and updating, two

key components of working memory. This possibility

is certainly plausible, given prior demonstrations (cf.

D.C. Gooding et al. / Schizophrenia Research 82 (2006) 27–37 35

Jutai, 1989) that individuals characterized by positive

schizotypy show spatial attention abnormalities in-

volving early information processing. On the other

hand, both Per-Mag and SocAnh participants have

demonstrated subtle working memory impairments in

past investigations (Park et al., 1995; Tallent and

Gooding, 1999; Gooding and Tallent, 2003); attribut-

ing both groups’ lowered performance on the CPT-IP

to a working memory deficit offers a parsimonious

account for these data.

Our main finding, namely, that there was a

significant difference in attentional performance be-

tween the psychometrically identified schizotypal

participants and the controls, is consistent with

previous findings of sustained attention deficits in

individuals at risk for the later development of

schizophrenia-spectrum disorders, such as the off-

spring, siblings, and parents of schizophrenia patients.

These data are consistent with the assertion (Chen and

Faraone, 2000; Cornblatt and Keilp, 1994; Cornblatt

and Malhotra, 2001) that sustained attention impair-

ment is an indicator of a schizophrenia diathesis.

However, additional investigation is necessary in

order to further evaluate the claim that sustained

attention deficits may serve as an endophenotype for

use in identifying genes conferring risk for schizo-

phrenia. Our sample, like prior samples of psycho-

metrically identified schizotypes, relied upon college

undergraduates. Due to the preponderance of high

functioning, cognitively intact participants in college

samples, they are by no means representative of the

general population. Additional investigation of CPT

performance in community-derived samples is neces-

sary in order to further establish the relationship

between schizotypy and attentional impairments. To

date, there have been no studies of community-

yielded samples tested using a version of the CPT

considered sufficiently challenging to allow asymp-

tomatic individuals to display subtle deficits which

may not be picked up with easier versions (cf.

Borgaro et al., 2003). It remains to be seen whether

the level of sustained attentional performance in a

community-derived sample of schizotypes is indica-

tive of a greater deficit (relative to controls) than that

displayed by the college-derived sample of schizo-

types that have been studied thus far.

In summary, the present study replicates and

extends the literature by demonstrating lowered

attentional functioning in questionnaire-identified

schizotypes characterized by positive schizotypy

(i.e. perceptual aberrations and/or magical ideation)

as well as those characterized by negative schizo-

typy (i.e. social anhedonia). These findings are con-

sistent with previous attentional studies of

genetically, clinically, and psychometrically defined

schizotypes which support the notion that sustained

attention deficits may be an endophenotype for use

in studies of vulnerability to schizophrenia. Given

this increasing empirical support, as well as the

converging lines of evidence suggesting that there

are multiple ways to successfully identify individ-

uals at heightened risk for the later development of

schizophrenia-spectrum disorder, perhaps the time

has come for the combined use of high-risk stra-

tegies to further elucidate the developmental trajec-

tory from risk to manifest disorder (cf. Gooding

and Iacono, 1995).

Acknowledgment

The authors gratefully acknowledge the invaluable

consultation of Ms. Simone Roberts. Comments on an

earlier draft of the manuscript by Dr. Jacqueline G.

Braun are also acknowledged. This research was

supported by a Wisconsin/Hilldale Undergraduate/

Faculty Fellowship.

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