Extreme Elemental Processing in a High Schizotypy Population: Relation to Cognitive Deficits

Schizotypy is associated with difficulty maintaining multiple hypotheses

Among neurocognitive accounts of delusions, there is a growing consensus that it is the certainty with which delusions are held, rather than their content that defines some beliefs as delusional. On a continuum model of psychosis, this inappropriate certainty ought to be present (albeit in an attenuated form) in healthy adults who score highly in schizotypy. It was hypothesised that this might be most evident in circumstances where the environment provides incomplete or probabilistic information, which thereby forces the participant to hold two imperfectly supported, concurrent hypotheses in mind. A cued visual search task was used to measure people's capacity to use partially predictive information (i.e., a cue that predicted the target may occur in one of the two locations) to facilitate speeded responding. As hypothesised, people's performance on the trials that required holding two hypotheses in mind concurrently was significantly and specifically associated with the positive components of schizotypy. This finding is consistent with a hyperfocusing of attention in schizophrenia, and may help explain why delusion-prone individuals have a tendency to "jump to conclusions" or be resistant to disconfirming information when faced with multiple, partially supported hypotheses.

Impaired perceptual processing of facial expression categorization in social anhedonia

The current event-related potential study investigated the perceptual processing of the categorization advantage of happy over sad faces in social anhedonia with a nonclinical sample. A high social anhedonia (HSA, N = 25) group and a low social anhedonia (LSA, N = 27) group performed a facial expression categorization task during which they classified facial expressions (happy, neutral, sad), irrespective of face orientation (upright, upside-down). Behaviorally, happy faces were identified more quickly than sad ones in the upright but not inverted orientation. Electrophysiologically, the LSA group showed earlier N170 latencies for happy than for sad faces in the upright but not upside-down orientation, whereas the HSA group did not show any expression effect on N170 latencies. Moreover, N170 and P2 amplitude results revealed that HSA relative to LSA individuals showed delayed neural discrimination between happy and sad faces. These results suggest that social anhedonia is associated with a deficit of perceptual processing during facial expression categorization.

[Oculomotor activity as an indicator of disturbances in perception and programming in patients with schizotypal disorder]

AIM

To consider the patterns of stimuli analysis and task execution in conditions of voluntary and involuntary attention in people with schizotypal disorder from the psychopathological and psychological points of view.

MATERIAL AND METHODS

A total of 40 subjects were examined including 16 patients diagnosed with schizotypal disorder, 13 with personality disorders and 11 without psychiatric pathology (controls). In the first part of the study, subjects looked upon various static images without any instructions, followed by a test with antisaccade task in vertical and horizontal directions; the last task duplicated the first, but the subjects were asked to remember the presented images as best as possible.

RESULTS

In the group of patients with schizotypal disorder, an increase in average and maximum fixation variance, its greater variation between images, and a decrease in the scanpath length were found. These differences were associated with the intentional focus of attention and several indicators of the accomplish efficiency of the antisaccade task.

CONCLUSION

The changes in fixative eye movements observed in individuals with schizotypal disorder indicate violations of information selectivity and construction of an image of future action. Assumptions about inadequacy of their perceptual strategy to the simultaneous one and the primacy of the sense-bearing (motivational) violations in the programming of saccadic activity were made.

Cue competition influences biconditional discrimination

When multiple cues are presented in compound and trained to predict an outcome, the cues may compete for association with an outcome. However, if both cues are necessary for solution of the discrimination, then competition might be expected to interfere with the solution of the discrimination. We consider how unequal stimulus salience influences learning in configural discriminations, where no individual stimulus predicts the outcome. We compared two hypotheses: (1) salience modulation minimises the initial imbalance in salience and (2) unequal stimulus salience will impair acquisition of configural discriminations. We assessed the effect of varying stimulus salience in a biconditional discrimination (AX+, AY-, BX-, BY+). Across two experiments, we found stronger discrimination when stimuli had matched, rather than mismatched, salience, supporting our second hypothesis. We discuss the implications of this finding for Mackintosh's model of selective attention, modified elemental models and configural models of learning.