0022-3018/01/18911–750 THE JOURNAL OF NERVOUS AND MENTAL DISEASE Copyright © 2001 by Lippincott Williams & Wilkins Vol. 189, No. 11 Printed in U.S.A. Cognitive Slippage in Schizotypic Individuals DIANE C. GOODING, PH.D.,1 KATHLEEN A. TALLENT, M.S.,2 and JEANETTE V. HEGYI, B.A.2 The Miers and Raulin Cognitive Slippage Scale was used to assess subtle thought disorder, and the Wisconsin Card Sorting Test (WCST) was used to assess cognitive performance in deviantly high scorers on the Perceptual Aberration and Magical Ideation Scales (N ⫽ 63), high scorers on the revised Social Anhedonia Scale (N ⫽ 62), and in control subjects (N ⫽ 83). Results indicate that schizotypic individuals are more likely to report greater cognitive slippage and less likely to achieve as many WCST categories as controls. Individuals with both positive and negative symptoms of schizotypy reported higher levels of cognitive slippage than those individuals reporting only negative schizotypy. Additionally, the results confirm the presence of an especially high-risk group of psychosis-prone individuals, namely, those individuals with deviant scores on the revised Social Anhedonia Scale who possess additional indicators of schizotypy. —J Nerv Ment Dis 189:750 –756, 2001 had the highest diagnostic power. Thus, the findings of Fossati et al. (2001) are consistent with Meehl’s (1990) suggestion that cognitive slippage is an important aspect of schizotypy. Several studies have indicated the multidimensional nature of schizotypy. There are at least two orthogonal factors of schizotypy, namely, a cognitive/perceptual distortion factor and an anhedonia factor (Kelly and Coursey, 1992; Lipp et al., 1994). Until recently, most of the research on psychosisproneness and schizotypy has focused on the cognitive/perceptual distortion factor; these studies have typically relied upon the Perceptual Aberration Scale (Chapman et al., 1978) or the Magical Ideation Scale (Eckblad and Chapman, 1983). Increasingly, there is research and clinical interest in negativesymptom schizotypy, which is characterized by anhedonia. Heightened interest in social anhedonia is partly based on Kwapil’s (1998) report that the Social Anhedonia Scale independently predicts the development of schizophrenia-spectrum disorders, as well as Blanchard et al.’s (2000) suggestion that hedonic capacity, as measured by the revised Social Anhedonia Scale, may be a taxonic indicator of schizotypy. There are several supporting lines of evidence which suggest that the combination of Social Anhedonia and Magical Ideation Scales may identify an especially high-risk group of psychosis-prone individuals. Prior investigations indicate that social anhedonia may serve as a potentiator of psychosisproneness among high scorers on the Magical Ideation Scale. Individuals identified by high scores on the Magical Ideation Scale and the revised Social According to Meehl, defective control over one’s associations is one manifestation of the underlying integrative neural defect (schizotaxia) that characterizes individuals with a heightened liability for the development of schizophrenia (Meehl, 1962, 1990, 2001). Cognitive slippage, believed to be the mildest form of such thought disorder, is characterized by abnormal associations and an inability to keep track of one’s thoughts (Kagan and Oltmanns, 1981; Levine et al., 1996). Thus, cognitive slippage should be observed more frequently in schizotypal individuals than in normal controls. Individuals with the schizotypal personality organization can vary in terms of the extent of their clinical (de)compensation. Some individuals with the schizotypal personality organization may be diagnosed with schizophrenia-spectrum disorders such as schizotypal personality disorder. In their study of 564 psychiatric inpatients and outpatients, Fossati et al. (2001) applied exploratory latent class analysis and diagnostic efficiency statistics to the DSM-IV diagnostic criteria for schizotypal personality disorder. Their results indicated that odd thinking, aloofness, social withdrawal, and social anxiety 1 Departments of Psychology and Psychiatry, University of Wisconsin-Madison, 1202 W. Johnson Street, Madison, Wisconsin 53706. Send reprint requests to Dr. Gooding. 2 Department of Psychology, University of Wisconsin-Madison, Madison, Wisconsin. This research was supported by a grant from the Wisconsin Alumni Research Foundation to the first author and a Wisconsin/ Hilldale Undergraduate/Faculty Fellowship. The authors appreciate the feedback they received from Michael L. Raulin, Jean P. Chapman, and Loren J. Chapman on an earlier version of this paper. 750 COGNITIVE SLIPPAGE Anhedonia Scale (N ⫽ 28) were more likely to report psychotic-like experiences, and more likely to be rated as meeting symptom criteria for schizotypal personality disorder than control participants (N ⫽ 20; Kwapil et al., 1997). Past Investigations of Cognitive Slippage and Thought Disorder in Schizotypic Individuals Miller and Chapman (1983) found that individuals with high scores on the Perceptual Aberration Scale, Magical Ideation, and the Impulsive Nonconformity Scales (Chapman et al., 1984) were more likely to display deviant performance on measures of cognitive slippage. Similarly, Allen and colleagues (1987a, 1987b) also reported that relative to control subjects, psychosis-prone individuals identified on the basis of the combined Perceptual Aberration and Magical Ideation Scales were more likely to provide unusual and uncommon responses to stimulus words in a word association task. After administering a 10-card Rorschach Test to high (N ⫽ 30) and low (N ⫽ 26) scorers on the Perceptual Aberration Scale, Coleman et al. (1996) observed that the high perceptual aberration group received a significantly higher Thought Disorder Index score, made a higher number of thought disordered responses, and produced a higher number of idiosyncratic verbalizations. Finally, Duchene et al. (1998) observed that individuals with heightened scores on the Magical Ideation Scale generated less common words in response to a verbal fluency test. The Present Study To date, there have been no investigations of subtle thought disorder in individuals identified on the basis of the revised Social Anhedonia Scale. The primary intent of the present study was to examine whether individuals reporting social anhedonia display signs of cognitive slippage. Due to the prominence of social anhedonia in some conceptualizations of schizotypy (cf. Meehl, 1962), we hypothesized that psychosis-prone individuals reporting social anhedonia would also report higher levels of cognitive slippage than the normal controls. Rather than relying upon word association or verbal fluency tasks, we chose to use the Cognitive Slippage Scale (CSS), a measure specifically designed to tap subtle thought disorder. Given the moderate correlation between the CSS and the Perceptual Aberration and Magical Ideation Scales (Miers and Raulin, 1987), we expected that psychosis-prone individuals characterized by elevated Perceptual Aberration and/or Magical Ideation scale 751 scores would also report higher levels of cognitive slippage. Moreover, because formal thought disorder is characterized primarily by disorganization, an aspect of positive symptomatology, we hypothesized that the individuals reporting positive schizotypal characteristics (such as perceptual aberration and magical ideation) would have higher CSS scores than individuals reporting negative schizotypal characteristics such as anhedonia. A second goal of this study was to examine whether individuals with higher levels of cognitive slippage show behavioral signs of cognitive disturbance. To investigate this, we assessed participants’ performance on the Wisconsin Card Sorting Test (WCST). We hypothesized that individuals reporting higher levels of cognitive slippage would be more likely to show subtle performance deficits on the WCST, a measure of higher-order cognitive functioning. Methods Screening Procedure The high-risk and control subjects were drawn from a sample of 1279 male and 2034 female undergraduate students who were screened using a 179item true-false self-report questionnaire called the Survey of Attitudes and Experiences. The questionnaire consisted of intermixed 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.3) as well as the Chapman Infrequency Scale (Chapman and Chapman4). The Chapman Infrequency Scale was used to exclude those participants who responded randomly to the items; individuals who endorsed more than two items on the scale were excluded from further study. There were two groups of at-risk subjects, namely, the Per-Mag group and the SocAnh group. Due to the high correlation between the Perceptual Aberration Scale and the Magical Ideation Scale, individuals scoring high (at least 2 SD beyond the same-sex sample mean) on either of these scales were assigned to the Per-Mag group. An example of an item on the Perceptual Aberration Scale is “Parts of my body occasionally seem dead or unreal” (keyed true). An example of an item on the Magical Ideation scale is “Good luck charms don’t work” (keyed false). The Social Anhedonia (SocAnh) group 3 Eckblad ML, Chapman LJ, Chapman JP, Mishlove M (1982) The Revised Social Anhedonia Scale. Unpublished test. 4 Chapman LJ, Chapman JP (1983) Infrequency Scale. Unpublished test. 752 GOODING was made up of individuals who obtained scores at or beyond 2 SD from the same-sex sample mean on the revised Social Anhedonia Scale. The revised Social Anhedonia Scale includes items such as “I sometimes become deeply attached to people I spend a lot of time with” (keyed false). The controls were individuals who received gender-normed standardized scores of less than .5 SD on all of the Chapman scales. Participants After psychometric screening, subjects were invited to participate in a multiple-session study of “individual differences and brain functioning.” Individuals who gave their informed consent were screened for a history of learning disabilities, epilepsy, and/or traumatic brain injury. Potential participants were also screened for current mood disorder as well as a personal history of psychotic illness and/or any psychoactive substance use disorder. Control subjects were also screened for family history of psychotic illness. The resultant sample consisted of two hundred and eight undergraduates. There were 63 Per-Mag subjects (30 male, 33 female), 62 SocAnh (31 male, 31 female) subjects, and 83 control (31 male, 52 female) subjects. Assessment All participants were tested individually. The participants were administered the Cognitive Slippage Scale (CSS; Miers and Raulin, 1987). The CSS is a 35-item, true-false self-report measure designed by Miers and Raulin. The CSS has good psychometric properties, such as high internal consistency reliability (.87 for male and .90 for female subjects; Miers and Raulin, 1987). Although the scale was originally developed on undergraduate students, it was designed to identify schizotypic characteristics such as speech deficits and confused thinking. Subsequent studies (cf. Osman et al., 1992) indicate that it has good test-retest reliability in both clinical (schizophrenia patients) and nonclinical populations. The CSS contains items related to the ability to keep track of one’s thoughts and the reporting of speech deficits and/or confused thinking. It appears that the CSS taps both positive and negative aspects of thought disorder. Several items in the CSS assess incoherence (“Often when I am talking I feel that I am not making sense”; keyed true), derailment (“I have no difficulty in controlling my thoughts”; keyed false), and disorganization (“My thoughts are orderly most of the time”; keyed false), whereas some of the items tap processes such as blocking (“Sometimes et al. my thoughts just disappear”; keyed true), poverty of content of speech (“I think I am reasonably good at communicating my ideas to other people”; keyed false), and alogia (“There have been times when I have gone an entire day or longer without speaking”; keyed true). Eighteen of the scale items are reverse coded (negatively keyed) to control for acquiescent response bias. High scores on the CSS scale indicate the presence of cognitive slippage. The WCST was used as a measure of overall higher order cognitive functioning. A computerized version of the WCST (Harris, 1988) was administered using the standardized guidelines provided in the test manual (cf. Heaton et al., 1993). Card stimuli were presented on a computer monitor, and the subjects were instructed to infer the matching principle from the feedback provided (either “right” or “wrong” is flashed upon the screen, depending upon the subject’s response). The WCST was scored using the (Harris, 1988) program provided with the computerized version. Performance on the WCST was scored in terms of number of categories achieved, number and percentage of perseverative errors, number of nonperseverative errors, number of trials to complete first category, conceptual level achieved, and failure to maintain set. IQ was measured to ensure that any possible group differences on the CSS could not be attributed to differences in intellectual ability. Time constraints precluded the use of the entire revised Wechsler Adult Intelligence Scale (WAIS-R; Wechsler, 1981). Vocabulary and Block Design subtests were administered to obtain an estimate of participants’ full scale IQ. This two-subtest short form of the WAIS-R (Silverstein, 1982) yields scores that are highly correlated with full scale scores (cf. Hoffman and Nelson, 1988; Missar et al., 1994), though they overestimate full scale IQ by an average of 2 points (Ryan et al., 1988). All participants gave their informed consent after the nature of the investigation was explained. All participants received extra credit points for their participation. Results Table 1 provides the mean Chapman scale scores, age, and estimated full-scale IQ scores for each group. The three groups did not differ in age (F[2,205] ⫽ .33, NS); the mean age was 19.02 years. The three groups did not differ in terms of gender (␹2[2] ⫽ 2.72, NS). There were no significant between-group differences in terms of estimated IQ (F[2,205] ⫽ .22, NS). COGNITIVE SLIPPAGE 753 TABLE 1 Demographic Characteristics, Chapman Scale Scores, CSS, and WCST Scores by Group Group Per-Mag (N ⫽ 63) Variable SocAnh (N ⫽ 62) Controls (N ⫽ 83) Mean SD Mean SD Mean SD 18.94 114.48 (0.84) (9.78) 19.10 115.60 (1.55) (10.25) 19.04 115.35 (0.89) (9.93) Perceptual Aberration Magical Ideation Social Anhedonia Physical Anhedonia 16.87 21.13 8.22 7.79 (6.98) (3.98) (4.63) (5.11) 7.63 9.55 20.97 16.68 (5.75) (5.00) (3.59) (7.94) 2.24 5.49 3.65 6.00 (1.96) (2.96) (2.29) (2.80) CSS Total score 11.37 (6.22) 9.27 (7.22) 3.88 (2.59) WCST Categories achieved Perseverative errors Nonperseverative errors Failure to maintain set Trials to first category Conceptual level 5.75 10.10 9.02 0.83 15.87 67.78 (0.98) (6.64) (7.11) (1.19) (17.23) (8.43) 5.73 10.23 10.69 0.77 13.40 67.15 (0.96) (8.09) (9.13) (1.12) (5.48) (12.16) 6.00 7.61 7.98 0.45 13.24 67.61 (0.00) (3.01) (4.97) (0.63) (5.71) (6.19) Age Estimated IQ Cognitive Slippage Scale The reliability characteristics of the CSS were examined by computing coefficient alpha (Cronbach, 1951). Coefficient alpha for the entire sample was .90. Coefficient alpha was .91 for the female participants and .88 for the male participants. Mean total scores by group are provided in Table 1. The three subject groups differed significantly in terms of total scores on the CSS (F[2,205] ⫽ 36.99, p ⬍ .001). The Per-Mag group reported significantly more cognitive slippage than the controls (t[78] ⫽ 8.98, p ⬍ .001). Similarly, the SocAnh group reported significantly more cognitive slippage than the controls (t[73] ⫽ 5.62, p ⬍ .001). We observed a trend whereby the Per-Mag group reported more cognitive slippage than the SocAnh group, though the difference did not reach statistical significance (t[123] ⫽ 1.74, p ⫽ .085). with higher Magical Ideation Scale scores reported more cognitive slippage (mean score ⫽ 11.17, SD ⫽ 8) than the other SocAnh individuals (mean score ⫽ 7.5, SD ⫽ 6); this difference was statistically significant (t[50] ⫽ 2.02, p ⬍ .05). We also compared the CSS scores of SocAnh subjects above (mean score on Perceptual Aberration Scale ⫽ 3.4, range, 0 to 6) and below (mean score on Perceptual Aberration scale ⫽ 12.5, range, 7 to 24) the group median in terms of Perceptual Aberration scores. The 33 SocAnh participants with low Perceptual Aberration Scale scores reported lower levels of cognitive slippage (mean score ⫽ 7.6, SD ⫽ 6) than the 29 SocAnh participants with moderately high Perceptual Aberration Scale scores (mean score ⫽ 11.14, SD ⫽ 8); this difference approached statistical significance (t[60] ⫽ 1.95, p ⫽ .056). Wisconsin Card Sorting Test Multiple Indicators of Schizotypy and Their Association with Cognitive Slippage We compared the CSS scores of SocAnh subjects above and below the group median in terms of Magical Ideation scores. By splitting the scores at the median (8), we created a low Magical Ideation SocAnh group (mean score on Magical Ideation scale ⫽ 5.5, range 1 to 8) and a high Magical Ideation SocAnh group (mean score on Magical Ideation scale ⫽ 13.9, range 9 to 21). Comparison of the high Magical Ideation, SocAnh group (N ⫽ 30) with the low Magical Ideation, SocAnh group (N ⫽ 32) revealed a significant difference. SocAnh individuals Mean scores for each WCST performance index are provided in the bottom half of Table 1. Nonparametric tests were used to compare the groups’ WCST performance scores because of violation of the assumption of homogeneity of variance. The groups were compared first with the Kruskal-Wallis test (Siegel, 1956). Follow-up group comparisons were performed with the Mann-Whitney U-test, with U scores transformed into the normally distributed z-statistic. There was a significant group difference in terms of number of categories achieved (␹2 ⫽ 7.84, p ⬍ .05). The Per-Mag group achieved fewer categories than the controls (z ⫽ ⫺2.60, p ⬍ .01), as GOODING 754 did the SocAnh group (z ⫽ ⫺2.89, p ⬍ .01). However, the Per-Mag and SocAnh subjects did not differ from each other in terms of number of WCST categories achieved (z ⫽ ⫺.32, NS). No other betweengroup comparisons on the WCST were significant. The Association between Self-Reported Cognitive Slippage and WCST Performance We were interested in examining whether selfreported levels of cognitive slippage would be associated with a behavioral index of cognitive functioning, namely, the WCST. A comparison of participants above and below the median (a score of “6” on the 35-item scale) revealed that individuals (N ⫽ 117) below the median achieved higher WCST categories than the individuals (N ⫽ 91) who scored above the median (Z ⫽ 2.61, p ⬍ .01). Higher CSS scores were also associated with a greater number of WCST perseverative errors (Pearson r ⫽ .16, p ⬍ .01, onetailed). Higher CSS scores were also associated with achieving fewer categories on the WCST (Pearson r ⫽ ⫺.15, p ⬍ .05, one-tailed). High cognitive slippage was operationally defined as cognitive slippage scores greater than or equal to 2 SDs of the controls’ mean score. Thirty-five percent (72 of 208) of the entire sample reported high levels of cognitive slippage. Among the individuals reporting high levels of cognitive slippage, nearly 56% (40 of 72) were in the Per-Mag group, 39% (28 of 72) were in the SocAnh group, and only 6% (4 of 83) were in the control group. Among those individuals reporting a high level of cognitive slippage, we observed significant associations between CSS total scores and number of WCST perseverative errors (r ⫽ .20, p ⬍ .05, one-tailed) and between CSS total scores and number of WCST nonperseverative errors (r ⫽ .21, p ⬍ .05, one-tailed). We also observed that among individuals reporting high levels of cognitive slippage, higher CSS scores were associated with lower conceptual level scores on the WCST (r ⫽ ⫺.22, p ⬍ .05, one-tailed). No other correlations between the CSS and WCST reached statistical significance. Discussion The CSS appears to be a highly reliable measure. We found coefficient alphas that were high, consistent with the reliabilities that were previously reported (cf. Miers and Raulin, 1987; Osman et al., 1992). Using this measure, we replicated earlier findings (e.g., Allen et al. 1987a; Coleman et al., 1996) that found subtle thought disorder in individuals with high scores on the Perceptual Aberration Scale. et al. We also extended earlier studies by demonstrating that psychosis-prone individuals characterized by predominantly negative schizotypy, i.e., the individuals reporting social anhedonia, also experience cognitive slippage. Research on schizophrenia patients has shown that thought disorder is a multidimensional construct. Andreasen (Andreasen, 1979; Andreasen and Olsen, 1982) distinguished between positive and negative categories of thought disorder. Positive thought disorder includes tangentiality, derailment, and incoherence, whereas negative thought disorder is characterized by poverty of speech and poverty of content of speech. Using factor analysis, Miller et al. (1993) demonstrated that alogia is comprised of two components: poverty of speech loaded onto a negative symptom factor, whereas poverty of content of speech loaded onto a disorganization factor. To our knowledge, this is the first study to assess subtle thought disorder in psychosis-prone individuals with social anhedonia. Cognitive slippage, like its more severe form, thought disorder, is associated with both positive and negative symptom components. We had hypothesized that individuals characterized by positive schizotypy would receive significantly higher CSS scores than those individuals characterized by negative schizotypy. Although the PerMag group reported higher levels of cognitive slippage than the SocAnh group, this difference did not reach statistical significance. Interestingly, we observed that individuals who possessed two hits of schizotypy, namely, aberrant Social Anhedonia Scale scores and either elevated Magical Ideation Scale scores or elevated Perceptual Aberration Scale scores reported more cognitive slippage than the SocAnh individuals without moderate levels of positive schizotypy. These results suggest that the combined use of the negative schizotypy and positive schizotypy indicators may identify a group of individuals with greater cognitive disturbance. One limitation of the present study is its reliance on a self-report measure of cognitive slippage. Despite the relatively low social desirability response set bias in the Cognitive Slippage Scale, it is possible that the apparent relationship between schizotypy and cognitive slippage indicated in our sample reflects common method variance due to acquiescence. Because both the psychosis-proneness scales and the CSS are self-report measures, the association between schizotypy and cognitive slippage may reflect some participants’ readiness to admit to psychopathology and/or peculiar experiences. Thus, it is noteworthy that there were small but significant relationships between the self-reported cognitive COGNITIVE SLIPPAGE disturbance and a behavioral measure of cognitive functioning, namely, the WCST. Although the CSS has been examined previously in individuals with schizophrenia, there may be a conceptual difference between the cognitive slippage endorsed by individuals with social anhedonia and the cognitive slippage endorsed by schizophrenic individuals, many of whom lack insight into their symptomatology. Given the uncertainty regarding the validity of the Cognitive Slippage Scale as a measure of thought disorder in nonpatient samples, future investigations would be strengthened by the inclusion of an objective measure of thought disorder along with the CSS. Social anhedonia is presently an imperfect index of negative schizotypy; hence, individuals reporting social anhedonia may develop non-schizophreniarelated disorders such as depression, or they may have outcomes such as schizophrenia spectrum disorders. In the present study, we demonstrated that some of our putatively at-risk sample, identified on the basis of their scores on the Chapman PsychosisProneness Scales, possess at least three of the four posited schizotypal source traits (Meehl, 1962), namely, cognitive slippage, anhedonia, and interpersonal aversiveness. In his later writings, Meehl (1990, 2001) has deemphasized the role of anhedonia, rendering it less of a causal factor and more of a mediating factor (i.e., 1 of 13 polygenic potentiators that along with adverse environmental factors influence the clinical outcome of the schizotype). Nonetheless, Meehl maintained that manifest anhedonia (hypohedonia) is one of the clinical signs of the schizotypal personality. Thus, individuals reporting cognitive slippage as well as social anhedonia are proposed to be at an especially heightened risk for the later development of schizophrenia and schizophrenia-spectrum disorders. In summary, this study supports the notion that individuals with social anhedonia display schizotypic characteristics such as cognitive slippage. Thus, this study is consistent with prior findings (cf. Gooding et al., 1999; Tallent and Gooding, 1999) that some individuals with social anhedonia display subtle signs of cognitive impairment. Meehl (1989, 1990) has posited the existence of genophenocopies of schizotypes. Such individuals are false positives, because although they may resemble schizotypes, they lack the soft neurological signs and aberrant psychophysiology that characterizes individuals who possess the schizotaxic gene. The presence of cognitive slippage may well serve as another avenue by which to distinguish between true schizotypes, i.e., those individuals possessing the genetic diathesis for 755 schizophrenia, and the genophenocopies (i.e., the so-called SHAITUs; Meehl, 1989). 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