PsychologicalReports, 1992, 70, 131-136. O Psychological Reports 1992 RELIABILITY AND VALIDITY O F THE COGNITIVE SLIPPAGE SCALE IN TWO POPULATIONS ' AUGUSTINE OSMAN, LISA VALERI, JOYLENE R. OSMAN, KEITH JONES University of Northern Iowa, Cedar Falls Summary.-Analyses of responses from a clinical sample of 120 patients (primarily schizophrenics) and from 158 college students to the Cognitive Slippage Scale, a scale designed by Miers and Raulin to identdy speech deficits and confused thinking in schizophrenic and schizotypal personality disorders showed high internal reliability; Cronbach's coefficients alpha were .89 and .86 in the clinical and college student samples, respectively. The mean scale scores sigdicantly differentiated the two samples. Also, change scores over 4 wk. showed adequate stability for both samples. Item analysis indicated Items 11, 20, 21, and 28 may not reliably discriminate between schizophrenic and college student samples. Over-all, these preliminary results are consistent with the reliabiliry and validity of the scale. Several lines of investigation have implicated cognitive slippage, sustained attentional dysfunction, intense ambivalence, social fear, and unusual perceptual experiences as central to the psychopathology of both schizophrenia and schizotypal personality disorders (Cornblatt & Erlenmeyer-Kimling, 1985; Dochertz, Van Kammen, Siris, & Marder, 1978; Gunderson, Siever, & Spaulding, 1983; Kendler, 1985; Lenzenweger, Cornblatt, & Putnick, 1991; Lenzenweger & Loranger, 1989; Meehl, 1962). In recent years, several selfreport measures have been developed for assessing symptoms related to both disorders. For example, the Perceptual Aberration Scale (Chapman, Chapman, & Raulin, 1978), a 35-item self-report measure, is designed to measure disturbances and distortions in the perception of one's body image and other objects. The Magical Ideation Scale (Eckblad & Chapman, 1983) measures magical ideations such as telepathy and clairvoyance. The Social Fear Scale (Raulin & Wee, 1984) measures specific social-interpersonal behaviors associated with schizotypal personality while the Intense Ambivalence Scale (Raulin, 1984) assesses both negative and positive feelings toward the same event. Reliability and validity data have been reported for most of these instruments (e.g., Allen, Chapman, Chapman, Vuchetich, & Frost, 1987; Chapman, Edell, & Chapman, 1980; Chapman, Chapman, & Miller, 1982; Hewitt & Claridge, 1989; Osman, Jones, & Osman, 1990). 'Portions of this paper were resented at the 71st Annual Convention of the Western Psychological Association in cali&rnia. We thank Mary Howard for her assistance wlth the statistical analysis and the anonymous referees for their comments on an earlier verslon of this paper. Requests for reprints should be addressed to Augustine Osman, Department of Psychology, University of Northern Iowa, Cedar Falls, IA 50614-0505. 132 A. OSMAN.ETAL. Miers and Raulin (1985) have recently developed a 35-item, true-false, self-report measure of cognitive slippage. This measure, Cognitive Slippage Scale, was designed to identify specific speech deficits and confused thinking found in individuals with schizophrenia and schizotypal personality disorders. The scale was developed in a series of studies involving undergraduate students, but the authors noted that it could be used in identifying cognitive distortions among other populations as well. However, the psychometric properties of this scale have not yet been well established with clinical and nonclinical samples. The purpose of the present study was to investigate the reliability and validity of the Cognitive Slippage Scale in both clinical and undergraduate samples. Data concerning the psychometric adequacy of the scale will enhance its suitability for research with the above populations. Subjects The clinical sample consisted of patients admitted consecutively to an inpatient, state-supported psychiatric hospital. Inclusion of subject involved an admitting psychiatrist's diagnosis (based upon the use of structured clinical interview and adequate review of medical history) of schizophrenia or schizotypal personality disorders (DSM-111-R). Those subjects who met the criterion for inclusion but also presented evidence of severe mood disorder, substanceldrug abuse, mental retardation, or any significant organic problems were excluded. Because the sample of schizotypics (7) was small, these were excluded from further data analyses. Thus, the clinical sample consisted primarily of 55 men and 65 women (Mean age = 30.7 yr., range 24 to 38 years) with diagnoses of schizophrenia. Of the 120 schizophrenics, 82.5% had completed high school, while only 17.5% had completed the eleventh grade or less. The college student sample consisted of 67 undergraduate men and 91 women (Mean age = 19.4 yr., range 18 to 33 years) from a variety of Introductory Psychology classes. Participants in both samples were Caucasians. Measures and Procedure All participants completed the Cognitive Slippage Scale (Miers & Raulin, 1987) and a 5-item Satisfaction with Life Scale (Diener, Emmons, Larsen, & Griffin, 1985). Data were analyzed for the Cognitive Slippage Scale alone. Seventeen of the scale items are negatively keyed while 18 are positively keyed. High scores on this scale suggest the presence of severe speech deficits and confused thinking. The schizophrenic sample completed the above measures individually in a quiet testing room within a week after admission to a unit. Data on the schizophrenic sample were collected over an 18-1110. period. The college stu- 133 COGNITIVE SLIPPAGE: RELIABILITY, VALIDITY dents completed the measures in small groups. To examine temporal stability, the measures were readministered four weeks after the initial administrations. Written informed consent was provided by each participant. All medical and psychological chart review, recruiting of subjects, and administration of questionnaires were carried out by research assistants who were trained seniors. RESULTS AND DISCUSSION The results are analyzed both separately and jointly for the clinical and college student samples. Reliability The reliability characteristics of the scale were examined by coefficient alpha (Cronbach, 1951). These results are shown in Table 1. Coefficient alpha was .89 for the schizophrenic sample and .86 for the college students. Within the schizophrenic sample, the alpha value for the women (.91) was higher than that for the men (.86), while for the college students, the alpha value was higher for the men (.YO) than for the women (.81). Miers and Raulin reported slightly higher alpha values for the women (.90) than for the men (.87) in their college samples. TABLE 1 MEANS,STANDARDDEVIATIONS AND RELIABILITY ESTIMATES FORTHE TWOSAMPLES Sample n M 120 28.7 Schizophrenic 158 5.7 College Students Note.-Maximum score = 35, Minimum score = 0. SD a rct 6.09 0.89 0.75 5.04 0.86 0.80 Test-retest reliabilities, over a 4-wk. period, showed adequate stability for 66.7310 of the schizophrenic (r,, = .75, n = 79, p e . 0 5 ) and 95% of the college student (r,, = .80, n = 149, p<.05) samples. These results show that moderate to high reliability was achieved for the scale in the two samples. Validity The mean scale score for the schizophrenic sample was significantly higher (i.e., they endorsed more items in the keyed direction) than for the college student sample, 28.71 (SD = 6.09) versus 5.73 (SD = 5.0), respectively (t,,, = -34.36, p < .001). Item Analysis An item-total correlation analysis was obtained to examine further the internal consistency of the scale. For the schizophrenic sample, positive and significant correlations were obtained for each item with the sum of the remaining 34 items (range -.079 to .65), except two items: Item 3 (alpha = .89, if item is deleted) and Item 28 (alpha = .90, if item is deleted; this item 134 A. OSMAN,ET AL. correlated negatively with the remaining 34 items). The alpha value, when both items were deleted, was only .90. Similarly, among the college students, Item 28 (alpha = .87, if item is deleted) was negative and nonsignificant at the .05 level. All other item-total correlations were positive and significant. Using an analysis of item alternatives, we arbitrarily defined items endorsed in the keyed direction by either 40% or more of the college student sample or 35% or fewer of the schizophrenic sample as "nondiscriminating" items. As shown in Table 2, four items met this criterion: Items 11 ("Sometimes my thoughts just disappear"), 20 ("Sometimes when I try to focus on an idea, so many other thoughts come to mind that I find it impossible to concentrate on just one"), 21 ("I have no difficulty in controlling my thoughtsM),and 28 ("The way that I process information is very different from the way in which other people do"). However, the removal of these items resulted in the same alpha values in the schizophrenic (.89) and college student (.86) samples. The present study investigated the psychometric properties of the Cognitive Slippage Scale in two different samples, schizophrenic and college undergraduates. The scale was designed to assess speech deficits and confused thinking in schizophrenic and schlzotypal personality disorders. As yet, normative and psychometric data for clinical and nonclinical samples have not been published. The results of the present study show that the scale has good internal consistency in the two samples. The responses of the subjects in each sample were stable over a 4-wk. period. An independent t test indicated that the schizophrenics achieved significantly higher scores on the scale than did the college undergraduates. Item-analysis data showed that the schizophrenic sample endorsed significantly more scale items in the keyed direction (more speech deficits and confused thinking) than did the college student sample. In the clinical literature, schizophrenics have been found to display more speech deficits and confused thinking than normal persons. Limitations of the present study include the lack of control for age, education, and socioeconomic status, as well as the use of college students as a control group. Also, we used psychiatric diagnoses alone to select our clinical sample. Ideally, the process of selecting clinical samples should include obtaining detailed descriptions of demographic and clinical history variables, as well as the use of multiple assessment measures. The present study should be viewed as providing preliminary normative and psychometric data on the Cognitive Slippage Scale on two populations. Studies are needed to evaluate the influence of the variables described above on the Cognitive Slippage Scale scores. Further psychometric and validational studies with different subgroups of clinical populations are needed to 135 COGNITIVE SLIPPAGE: RELIABILI'IY, VALIDITY TABLE 2 ITEM-TOTAL CORRE.LATIONS AND PERCENTAGE WHOENDORSED ITEN IN KEYEDD ~ C T I O N Item* Key 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 F T T T T F F F T F T F T F T F F T 20 T 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 F T F T T F F T T F Schizophrenic % r .83 .72 .79 .92 .83 .80 .88 .76 .88 .83 .78 .84 .92 .71 .84 .93 .89 .78 .81 .78 .93 .93 .73 .92 .79 .62 .68 .72 .79 .83 .75 .87 .93 .85 .87 .34 .47 .10 .47 .36 .30 .53 .63 .36 .49 .43 .49 .47 .65 .30 .36 .56 .58 .44 .49 .39 .31 .54 .33 .47 .54 .40 -.08 .61 .34 .54 .43 .30 .32 .41 T T F T F F *Actual items are given by Miers and Raulin (1987). College Students r % .19 .13 .15 .10 .07 .22 .14 .04 .18 .30 .41 .06 .05 .08 .06 .19 .ll .09 .20 .40 .45 .09 .06 .15 .18 .04 .35 .58 .10 .15 .03 .04 .07 .10 .22 .35 .43 .51 .35 .48 .45 .30 .30 .48 .38 .30 .47 .35 .50 .37 .42 .34 .42 .45 .37 .44 .46 .39 .41 .37 .30 .38 -.09 .30 .41 .45 .35 .51 .32 .33 enhance the usefulness of this scale in clinical practice and research. Also, the relationship between this scale and other validated measures of cognitive slippage could be investigated. REFERENCES ALLEN, J. J., CHAPMAN, L. J., CHAPMAN, J. F?, VUCHETICH, J. F?, & FROST,L. A. (1987) Prediction of psychotic-like symptoms in hypothetically psychosis-prone college students. ]ournu1 of Abnormal Psychology, 96, 83-88. 136 A. OSMAN, ET AL. CHAPMAN, L. J., CHAPMAN, J. P., & MILLER,E. N. (1982) Reliabilities and intercorrelations of eight measures of proneness to psychosis. Journal of Consulting and Clinical Psychology, 50, 187-195. CHAPMAN,L. J., CHAPMAN, J. P., & RAULIN,M. L. (1978) Body-image aberration in schizophrenia. Journal of Abnormal Psychology, 87, 399-407. CHAPMAN, L. J., EDELL,W. S., & CHAPMAN, J. P (1980) Physical anhedonia, perceptual aberration, and psychosis proneness. Schizophrenia Bulletin, 6, 639-653. CORNBLAT~, B., & ERLENMEYER-KIMLING, L. (1985) Global attentional deviance as a marker of risk for schizophrenia: specificity and predictive validity. Journal of Abnormal Psychology, 94, 470-486. CRONBACH, L. J. (1951) Coefficient alpha and the internal structure of tests. Psychometrika, 16, 297-334. DIENER,E., EMMONS,R. A,, LARSEN,R. J., & GRIFFIN,S. (1985) The Satisfaction with Life Scale. Journal of Personality Assessment, 49, 71-75. DOCHERTZ, J. P., VANKAMMEN,D. P., SIRIS, S. G., & ~ E R S. , R. (1978) Stages of onset of schizophrenic psychosis. American Journal of Psychiatry, 135, 420-426. ECKBLAD, M., & CHAPMAN, L. J. (1983) Magical ideation as an indicator of schizotypy. Journal of Consulting and Clinical Psychology, 51, 215-225. GUNDERSON, J. G., SIEVER,L. J., & SPAULDING, E. (1983) The search for a schizotype: crossing the border again. Archives of General Psychiatry, 40, 15-22. HE^, J. K., & CLARIDGE,G. (1989) The factor structure of schizotypy in a normal population. Personality and Individual Differences, 10, 323-329. KENDLEB. K. S . (1985) Diagnostic approaches to schizotypal personality disorder: a historical perspective. Schizophrenia Bulktin, 11, 538-553. LENZENWEGER, M. F., CORNBLATT, B. A,, & PUTNICK,M. (1991) Schizotypy and sustained attention. Journal of Abnormal Psychology, 100, 84-89. LENZENWEGER, M. F., & LORANGER, A. W. (1989) Psychosis proneness and clinical psychopathology: examination of the correlates of schizotypy. Journal of Abnormal Psychology, 98. 3-8. MEEHL, P. E. (1962) Schizotaxia. schizotypy, schizophrenia. American Psychologist, 17, 827838. MIERS,T. C., & RAULIN,M. L. (1985) The develo ment of a scale to measure cognitive slip page. Paper presented :nr the Eastern ~s~c!olo~ical Association Convention, Boston, MA, March, 1985. MERS, T. C., & h u m , M. L. (1987) Cognitive Slip age Scale. In K. Corcoran & J. Fischer (Eds.), Measures for clinical practice: a sourceboo!. New York: Free Press. Pp. 125-127. OSMAN,A,, JONES,K., & OSMAN,J. R. (1990) Psychometric properties of the Social Fear Scale. Psychological Reports, 67, 1367-1373. RAULIN,M. L. (1984) Development of a scale to measure intense ambivalence. Journal of Consulting and Clinical Psychology, 5 2 , 63-72. b u m , M. L., & WEE, J. L. (1984) The development and initial validation of a scale to rneasure social fear. Journal of Clinical Psychology, 40, 14, 784. Accepted December 18, 1991.