Individual differences in cognitive processes: Towards an explanation of schizophrenic symptomatology

Abstract

A study is reported that examined the relationship between a measure of schizophrenic-like characteristics (schizotypy) in normal subjects and cognitive inhibition. Both repetitive and semantic measures of priming were used. It was found that low schizotypes showed negative priming (i.e. longer reaction times to the re-presentation of initially ignored stimuli) while high schizotypes did not; high schizotypes exhibited semantic facilitation (i.e. shorter reaction times to previously ignored stimuli) but low schizotypes did not. A model is suggested, including both inhibitory and facilitatory processes, which can account for these findings. Theorizing about these processes is of interest as it may shed some light on the mechanisms involved in the specifically cognitive symptoms of schizophrenia.

Negative priming from ignored distractors in visual selection: A review

“…For example, Beech, Powell, McWilliam, and Claridge (1989) found that people with schizophrenia show diminished NP in comparison with a group of matched controls. Furthermore, university students who obtain high scores on questionnaire measures of schizophreniclike symptoms tend to show increased flanker interference from ignored distractors, but reduced NP relative to those with low scores on the same questionnaires Beech & Claridge, 1987;Beech et al, 1991). Once again, it should be noted that these results may indicate problems with retrieval mechanisms rather than with inhibitory mechanisms.…”

“…Several individual-difference studies have indeed found evidence for such an inverse relation between flanker interference and NP. To illustrate, Beech and his colleagues (Beech, Baylis, Smithson, & Claridge, 1989;Beech & Claridge, 1987;Beech, McManus, Baylis, Tipper, & Agar, 1991;Beech, Powell, MeWilliam, & Claridge, 1989) have demonstrated that subjects with high schizotypical personality traits are more susceptible to flanker interference from ignored distractors and also show less NP from the same distractors. A very similar pattern has been found both for older adultswho tend to show heightened distractibility and reduced NP relative to younger adults (Hasher et aI., 1991;Tipper, 1991)-as well as for young children (Tipper et aI., 1989).…”

Semantic priming in the prime task effect: Evidence of automatic semantic processing of distractors

“…When evidence for the inhibition of distractor identity is sought, researchers have mainly used identification tasks (Driver & Baylis, 1993;Driver & Tipper, 1989;Fuentes & Humphreys, 1996). To obtain evidence for the inhibition of central/semantic representations of distractors, categorization and naming tasks are preferred (Beech, McManus, Baylis, Tipper, & Agar, 1991;Tipper & Baylis, 1987;Tipper & Driver, 1988). To examine negative priming from locations, participants are asked to perform a localization task in the prime (Milliken, Tipper, & Weaver, 1994).1…”

Attentional window in schizophrenia and schizotypal personality: Insight from negative priming studies

“…Such studies can examine the relationship between schizotypal syndromes and NP in the absence of medication. There is considerable evidence supporting reduction of verbal NP effect in schizotypal individuals especially when positive syndromes are present (Beech & Claridge, 1987;Beech, McManus, Baylis, Tipper, & Agar, 1991;Beech et al, 1989;Moritz, Mass, & Junk, 1998). But Sturgill & Ferraro, (1997) found that deficits in verbal NP was correlated with elevated schizotypal traits.…”

“…Studies of schizotypal personality have shown that spatial NP is reduced in unmedicated schizotypal individuals, especially among those with elevated positive syndromes (e.g., Beech et al, 1991;Moritz et al, 1998;Park et al, 1996;Watson & Tipper, 1997).…”