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Background: We sought to develop a Dot Pattern Expectancy task (DPX) to assess goal maintenance for use in clinical trials. Altering the standard task created 5 versions of the DPX to compare-a standard version and 4 others. Alterations in the interstimulus interval (ISI) length and the strength of a learned prepotent response distinguished the different tasks. These adjustments were designed to decrease administration time and/or improve reliability of the data., Methods: We determined participant eligibility in an initial session (the first of 3) using clinical interviewing tools. The initial session also included a demographic assessment and assessments of community functioning and symptom severity. All versions of the DPX were administered, across 3 sessions. Specific deficits on the context processing compared with difficulty control condition were evaluated using mixed-effects logistic regression within a hierarchical linear model., Results: We analyzed the data from 136 control participants and 138 participants with schizophrenia. Relative to a difficulty control condition, patients performed worse than controls on context processing conditions that required goal maintenance. ISI did not predict errors. Stronger prepotency was associated with increased errors in the difficulty control relative to context processing condition for controls, which improved the interpretability of findings for patients. Reliability was acceptable for a version of the task with a 10-minute running time., Conclusions: The best compromise between task duration and interpretability occurred on a version with a short ISI and a strong prepotency.

To examine the relationship between emotional activation and information gathering in schizophrenia, the eye movements and emotional responses of 20 patients with schizophrenia and 10 patients without history of psychosis were recorded while viewing 30 images varying in pleasantness. Emotionally activating pictures were more extensively explored than neutral pictures by both groups but especially by schizophrenia patients. Comparison patients explored pictures more extensively during the early part of image exposure, whereas patients with schizophrenia took longer to engage in informative exploration. The scan path lengths and the proportions of fixation time spent in regions of interest did not differ between groups, although persons with schizophrenia had longer fixations and looked at fewer regions of interest in neutral pictures. Emotion reports did not differ between groups. Schizophrenia patients' results are consistent with the hypothesized normalizing effects of emotional activation on the distribution of attention.

The effects of aging on visuospatial attention were investigated with event-related brain potentials (ERPs). A central arrow pointed towards (75% valid cues) or away from (25% invalid cues) the location of upcoming visual targets to which subjects made two choice discriminations. Young and older adults responded faster following valid than invalid cues. The absolute magnitude of the cueing effect was larger for older than young subjects, but cueing effects were similar between groups when estimated proportionally to overall response time. Under the present conditions, the electrophysiological manifestations of visuospatial attention were similar for young and older adults. Early ERP components following the target stimulus (P1, N1, Nd1) were slower for older than young subjects, but amplitude was similarly affected by cueing in each group. The temporal correspondence between component latencies and the observed cueing effects are consistent with theories positing that attention amplifies the sensory gain of early perceptual processes. The observation that aging slowed latency of the ipsilateral but not the contralateral P1, is consistent with age differences in interhemispheric transfer times. A broadly distributed 200-400 ms validity effect on ERP amplitude was similar between groups in timing, spatial distribution, and magnitude. The 200-400 ms attention effect appeared to be a modulation of the P3 in younger subjects, as earlier observed. However, the present study dissociated the 200-400 ms attention effects from the P3 component because the P3 did not peak until 526 ms in older subjects.

Structural equation modeling (specifically, analysis of moment structures; J. L. Arbuckle, 1996) was used to evaluate the goodness of fit of a model of components of attention (A. F. Mirsky, B. J. Anthony, C. C. Duncan, M. B. Aheam, & S. G. Kellam, 1991) to neuropsychological test data from 2 samples. One sample consisted of psychiatrically normal persons with and without sleep-disordered breathing, and the other sample consisted of the adults studied by A. F. Mirsky et al. (1991), who gave rise to this model. That sample included psychiatric patients as well as normals. An exploratory data reduction procedure, principal-components analysis, suggested that attention might be conceptualized as composed of 4 independent elements or components: focus-execute, sustain, shift, and encode. Neither the proposed orthogonal model nor a model permitting correlated factors adequately fit either data set, suggesting that these 4 attention constructs are as yet not clearly validated in the measures used to assess them.

Objective: Previous studies of attention/information processing impairments in schizophrenia suggest that patients with the deficit syndrome should be characterized by impaired performance on measures of visual information processing. Therefore, the authors examined whether two measures of visual information processing, a degraded stimulus version of the continuous performance test and a forced choice span of apprehension task, were uniquely related to the deficit syndrome., Method: Performance on the continuous performance test and span of apprehension task was examined in 20 deficit and 56 nondeficit patients with schizophrenia and in 27 subjects in a normal comparison group., Results: Deficit patients performed significantly less well than both nondeficit patients and the normal comparison group on the continuous performance test and span of apprehension task. There were no significant differences between the nondeficit patients and the normal group on the continuous performance test, but nondeficit patients performed significantly less well on the span of apprehension task than the normal group. Differences between the deficit and nondeficit patients in performance on the continuous performance test and span of apprehension task were not related to total scores on the Brief Psychiatric Rating Scale factor 1 or on the Thought, Language, and Communication scale or to neuroleptic level., Conclusions: The results suggest that deficit patients are uniquely characterized by impaired performance on the continuous performance test. The deficit patients' differential performance on the continuous performance test may be related to either an inability to activate and allocate attention or an impairment in the perceptual organization of visual information.

Information-processing impairments have been suggested to be at the core of the cognitive deficits observed in schizophrenia and may represent preclinical markers of genetic vulnerability to the illness. Of particular importance in information-processing research have been measures such as the Continuous Performance Test (CPT) and the Partial Report Span of Apprehension (SPAN) that place high momentary loads on processing resources. The relationships between the two cognitive measures and between the two measures and clinical symptoms were examined in 50 patients with either DSM-III-R schizophrenia or schizoaffective disorder. The information-processing measures were modestly correlated with each other and with an estimate of verbal, but not nonverbal IQ. The SPAN was correlated with negative symptoms and the CPT with formal thought disorder. These results provide some evidence of convergent validity but also suggest that constructs other than high momentary processing load are implicated in their sensitivity to schizophrenia.

Posner et al. (1988) recently found a lateralized impairment in the shift of covert visual attention to the right visual field in acute schizophrenic patients. Strauss et al. (1991) did not find this lateralized attentional deficit in remitted neuroleptic-treated chronic schizophrenic outpatients. The present study examined the covert shifting of visuospatial attention in clinically ill inpatients with chronic schizophrenia and in nonpsychotic control subjects. Although patients with schizophrenia were slower in all conditions, no lateralized attentional abnormalities were found. Taken together, these studies suggest that neuroleptic treatment may affect a lateralized attentional impairment in chronic schizophrenia.

We compared covert shift of visual attention in patients with schizophrenia or bipolar disorder, both in states of remission, to normal controls to examine the persistence of lateralized attentional deficits into nonpsychotic states. Although patients were slower in all conditions than normals, there was no difference in pattern of attentional shift among the groups. This suggests that the left-hemisphere deficit in shift of covert attention in schizophrenia may be limited to periods of florid illness.

Distractibility and reaction time were measured in 25 clinically stable chronic schizophrenic subjects receiving psychotropic medications. Higher serum neuroleptic levels were associated with lessened distractibility. Extrapyramidal side effects and level of symptoms were each related to slow and variable reaction times.

Perceptual span was assessed in schizophrenic, bipolar affective disorder-manic, bipolar affective disorder-depressed, and nonpsychotic inpatients. Both schizophrenics and manics processed less information than depressives, and did not differ from each other. This suggests that reduced span may be a concomitant of psychoses characterized by distractibility and thought disorder, rather than a trait specific to schizophrenia.

Reduced perceptual span has been suggested to be a cognitive marker of vulnerability to schizophrenia. However, the specificity of this impairment in visual information processing to schizophrenia is not well established. This preliminary study examined perceptual span in schizophrenic and manic patients divided into subgroups with and without active symptomatology. Symptomatic patients had reduced span in comparison with less symptomatic groups, but there were no differences between schizophrenic and manic patients.

The reaction-time crossover phenomenon discovered by Rodnick and Shakow has come to be studied mainly with the embedded isotemporal sets procedure and indexed by the difference in reaction time to regular and irregular trials at a 7-second preparatory interval (PI). A 1983 report in this journal by Galbraith et al. (J Nerv Ment Dis 171:670-675) demonstrated that the magnitude of crossover at this PI was influenced by the duration of the preparatory interval immediately prior (PPI) to the first trial of the 7-second isotemporal blocks. Secondary analyses reported here extend the examination of PPI influences and indicate: a) that the crossover phenomenon as assessed in the embedded sets procedure is due mainly to the very slow reaction time to the first trial of the 1-second isotemporal blocks; and b) that crossover in this paradigm is partially due to uncontrolled PPI influences across the 1-, 3-, and 7-second embedded blocks. These are further reasons for returning to the original Rodnick-Shakow method as Galbraith et al. recommended.