Context, complexity, and cognitive processing in schizophrenia.

Background: Cohen et al.'s (1990, 1999) concept of context has been employed to explain various schizophrenic cognitive deficits. Braver et al.'s (2001) modified definition allows us to link context to cognitive complexity and explain a range of our experimental findings.

Method: Saccadic and manual responses to experimental paradigms involving familiar and unfamiliar versions of tasks varying in stimulus-response compatibility, response familiarity, and temporal factors were used. These include comparison of acoustic and visually driven saccades and antisaccades, manual and saccadic pattern reproduction, and colour (cognitively guided) saccades with two delay intervals.

Results: In one experiment, schizophrenic participants, unlike controls, made fewer errors on the auditory compared to the visual antisaccade task, suggesting that prepotent responses are more easily inhibited when stimulus-response compatibility is reduced. In a second experiment in which a left-right response sequence is reproduced manually or saccadically, schizophrenic performance is impaired when the novel and thus more complex saccadic response is required. In the third experiment, a colour signal is interpreted to determine the correct direction of a saccade. With two different blocked delay intervals, shortening the delay results in schizophrenic performance decline, suggesting difficulty adjusting to temporal context changes.

Conclusion: These results, together with our previous findings (Schooler et al., 1997a; Zahn et al., 1998) suggest schizophrenic context processing deficits become increasingly evident as contexts become more complex. These results may be due to microgaps in schizophrenic individuals' maintenance of context.