Mark F. Lenzenweger

The continuous performance test, identical pairs version: II. Contrasting attentional profiles in schizophrenic and depressed patients

The Continuous Performance Test-Identical Pairs version was administered to 14 schizophrenic patients, 17 depressed patients, and 28 normal controls. The task was divided into verbal and spatial stimuli, as well as no-distraction and distraction (verbal and auditory) conditions. Both patient groups displayed attentional impairments compared to normal subjects, but they differed from each other in specific profiles. Schizophrenic patients were characterized by a global impairment and a particular inability to focus on the critical stimuli, whether verbal or spatial. They also made an excess of random responses throughout the task but showed no evidence that attention declined from its initial level over time. Depressed patients did not display a global attentional deficit but did show a specific inability to attend to spatial as compared to verbal stimuli and, in particular, a confusion when the spatial stimuli were only slightly different. Performance on a secondary task in response to a change in expectation improved dramatically for depressed but not schizophrenic patients, suggesting a more efficient allocation strategy, a greater reserve of processing capacity, or more dependence on motivational factors in depressed patients. Schizophrenic and depressed patients were alike in extent of distractibility. Whereas normal controls improved with the onset of external distraction, schizophrenic and depressed patients deteriorated to an equal extent. Distractibility was thus concluded to be a correlate of acute psychiatric illness and not specific for schizophrenia.

Schizotypy and sustained attention

We examined sustained attention in 32 schizotypic and 43 normal control subjects from a large, randomly ascertained nonclinical university population. Schizotypy status was determined with the Perceptual Aberration Scale. Sustained attention was measured with the Continuous Performance Test-Identical Pairs. Schizotypic subjects displayed significantly poorer sustained-attention performance than did control subjects, as measured by d and overall hit rate. Although schizotypic subjects evidenced greater levels of anxiety and depression, sustained-attention performance was not significantly associated with these mental state factors. Our results provide evidence for a subtle sustained-attention deficit among schizotypes and are interpreted in light of previous attention research with actual schizophrenic patients as well as children at risk for schizophrenia. Utility of the psychometric high-risk strategy in psychopathology research is discussed.

Memory Distortion in People Reporting Abduction by Aliens

False memory creation was examined in people who reported having recovered memories of traumatic events that are unlikely to have occurred: abduction by space aliens. A variant of the Deese/Roediger-McDermott paradigm (J. Deese. 1959; H. L. Roediger III & K. B. McDermott, 1995) was used to examine false recall and false recognition in 3 groups: people reporting recovered memories of alien abduction. people who believe they were abducted by aliens but have no memories, and people who deny having been abducted by aliens. Those reporting recovered and repressed memories of alien abduction were more prone than control participants to exhibit false recall and recognition. The groups did not differ in correct recall or recognition. Hypnotic suggestibility, depressive symptoms, and schizotypic features were significant predictors of false recall and false recognition.

Empirical assessment of the factorial structure of clinical symptoms in schizophrenia: Negative symptoms

The factor structure of the Scale for the Assessment of Negative Symptoms (SANS) was examined in a confirmatory factor analysis that used the LISREL procedure. Four models of negative symptom factors were tested in 130 hospitalized schizophrenic patients. A three-factor model of diminished expression, social dysfunction, and disorganization generated by the authors yielded a superior fit to the data relative to the two-factor model of Liddle (1987b) and a unifactorial severity model. A four-factor model based on the original subscale formulation of the SANS failed to fit the data.

Models of positive and negative symptoms in schizophrenia: an empirical evaluation of latent structures.

The present investigation empirically evaluated three competing models of the relations between positive and negative symptoms in schizophrenia, namely the severity-liability model (Gottesman, McGuffin, & Farmer, 1987), Andreasens unidimensional bipolar model (Andreasen & Olsen, 1982), and Crows independent dual-process model (Crow, 1980a, 1980b). Using positive and negative symptom ratings based on 220 schizophrenic subjects, the results of a LISREL VI (Joreskog & Sorbom, 1984) confirmatory factor analysis revealed that Crows model of positive and negative symptoms provided the best fit to the observed data among the three models. The severity-liability model provided a modest fit to observed data, and Andreasens model fit the data poorly. Results are interpreted as supporting the validity of the positive and negative symptom distinction in schizophrenia and as providing substantive empirical support for Crows independent dual-process model. The methodological advantages of confirmatory factor analysis in the specification and evaluation of theoretical models in experimental and developmental psychopathology are discussed.

Deeper into the schizotypy taxon: on the robust nature of maximum covariance analysis.

Prior research has suggested that the latent structure of the schizotypy construct (P. E. Meehl, 1990) may be qualitative in nature and have a low base rate (L. Korfine & M. F. Lenzenweger, 1995; M. F. Lenzenweger & L. Korfine, 1992). These studies relied on the application of maximum covariance analysis (MAXCOV) to 8 true-false format items from a schizotypy measure. The current study sought to examine the robustness of those prior findings through MAXCOV analysis of fully quantitative measures of schizotypy. Measures of perceptual aberration, magical ideation, and referential thinking were analyzed using MAXCOV in a sample of 429 persons. The results of these analyses strongly support a latent taxonic structure for schizotypy and a low base rate for the schizotypy taxon. Furthermore, the members of the putative taxon reveal an increased level of deviance on a psychometric measure known to be associated with schizophrenia liability. The possibility that the dichotomous item format of those items analyzed previously with MAXCOV lead to spurious pseudotaxonicity is greatly diminished in light of these results.

Psychosis proneness and clinical psychopathology: examination of the correlates of schizotypy.

The present report examined the associations between the Perceptual Aberration Scale (PAS), a prominent psychometric index of hypothetical psychosis proneness, and several measures of clinical psychopathology in a nonpsychotic psychiatric sample (N = 101). Patients were examined by experienced clinicians using structured psychiatric interviews to assess DSM-III-R Axis I and II conditions and rated for anxiety, depression, severity of illness, and current adult social competence. Elevated scores on the PAS were most closely associated with anxiety and depression as well as schizotypal, schizoid, avoidant, and obsessive-compulsive personality disorder symptomatology. Hierarchical regression analysis identified schizotypal symptoms and anxiety as the two underlying psychopathological processes most useful in explaining variance in PAS scores. Results are interpreted as supporting both the clinical relevance and research utility of the PAS and enhancing the construct validity of Meehls model of schizotypy.

Auditory working memory and verbal recall memory in schizotypy

Deficits on verbal memory tasks, as well as on spatial and auditory working memory tasks, have been observed in schizophrenia patients. A useful strategy in the determination of the premorbid indicator status of specific cognitive and memory deficits observed in patients is to examine those persons at increased biological risk for schizophrenia (e.g. first-degree relatives), schizotypal personality disorder patients, and/or psychometrically identified schizotypes for comparable deficits, though perhaps less profound than those seen in actual patients. We examined verbal memory and auditory working memory functioning in 31 schizotypic and 26 normal control subjects from a large randomly ascertained non-clinical university population. Schizotypy status was determined psychometrically using the well-known Perceptual Aberration Scale. Contrary to our theory-guided expectations, noteworthy deficits in verbal memory and auditory working memory were not observed in the schizotypic subjects and the two experimental groups did not differ significantly on any of the memory measures. These results were discussed in light of prior results obtained using the spatial delayed response task (i.e. spatial working memory) and Wisconsin Card Sorting Test performance on these same subjects. The theoretical implications of these findings are discussed in relation to the putative processes involved in the working memory system, as well as in relation to the schizotypy construct.

Structured Interview of Personality Organization (STIPO): preliminary psychometrics in a clinical sample.

In this article, we describe the development and preliminary psychometric properties of the Structured Interview of Personality Organization (STIPO), a semistructured interview designed for the dimensional assessment of identity, primitive defenses, and reality testing, the three primary content domains in the model of personality health and disorder elaborated by Kernberg (1984; Kernberg & Caligor, 2005). Results of this investigation, conducted in a clinical sample representing a broad range of personality pathology, indicate that identity and primitive defenses as operationalized in the STIPO are internally consistent and that interrater reliability for all 3 content domains is adequate. Validity findings suggest that the assessment of ones sense of self and significant others (Identity) is predictive of measures of positive and negative affect, whereas the maladaptive ways in which the subject uses his or her objects for purposes of regulating ones self experience (Primitive Defenses) is predictive of measures of aggression and personality disorder traits associated with cluster B personality disorders. We discuss implications of these findings in terms of the theory-driven and trait-based assessment of personality pathology.

Consideration of the Challenges, Complications, and Pitfalls of Taxometric Analysis.

The taxometric analytic procedures developed by P. E. Meehl and colleagues represent powerful statistical tools for use in the evaluation of observed quantitative data for the possible existence of a qualitative latent class, natural subgroup, or, more commonly, a taxon. Taxometric methods, like any other statistical procedures, require thoughtful application, and the responsibility for proper interpretation of the results from a taxometric study lies with the investigator. Any investigator using taxometric methods must be mindful of those substantive and methodological issues that will facilitate the most fruitful utilization of the general taxometric approach, as well as those issues that will handicap or, perhaps, fatally flaw a taxometric investigation. A number of these issues are highlighted and discussed in this article, and a readers, writers, and reviewers guide for the evaluation of taxometric research reports is provided.