HEMISPHERIC DIFFERENCES IN SEMANTIC CONTEXT PROCESSING AS A FUNCTION OF SCHIZOTYPY

Semantic processing deficits are present in schizophrenia and are particularly evident on semantic priming tasks. Using high schizotypes (psychosis-prone individuals) can overcome some confounds involved in studying actively symptomatic schizophrenics. In the current study, 26 high and 32 low scorers on the O-LIFE schizotypy scale (from a sample of 251 students) were selected for testing. All subjects were administered a lexical-decision semantic priming task where half the stimuli had a short 200 ms stimulus onset asynchrony (SOA, length of time from onset of prime to onset of target) and half the stimuli had a long 750 ms SOA. In addition, half the words were of high frequency and half of a low frequency. There were no group differences in priming for words of different frequencies. Low schizotypes showed greater priming at the 200 ms SOA than at the 750 ms SOA, whilst individuals with high schizotypy showed the opposite pattern. The pattern shown by the low schizotypes replicates earlier work by the authors using other normal control samples; establishing that there is greater priming under conditions of automatic spreading of activation. Furthermore, the data shows there is not an increase in automatic spreading of activation in individuals with high schizotypy. There has been controversy in the schizophrenia literature over whether there is increased priming under automatic conditions. The current study suggests that, when confounds are controlled for, schizophrenia-like symptoms are not related to an increase in automatic spreading of activation.