Direct and indirect semantic priming with neutral and emotional words in schizophrenia: Relationship to delusions

Abstract

Introduction. Evidence is accumulating that suggests that semantic networks are abnormal in schizophrenia. Methods. To investigate this further, we examined priming in 42 schizophrenics and 28 normal controls on a lexical decision task involving three different prime-target conditions all at 700 ms stimulus onset asynchrony (SOA): directly semantically related, indirectly semantically related, and unrelated; and three types of emotional pairings: positive, negative, and neutral. Two schizophrenic groups were compared: nondeluded (no current delusions) and deluded. Results. Schizophrenic patients did not demonstrate significant direct priming overall, whereas controls did. However, when material was examined according to emotional pairing, the controls and deluded subjects demonstrated significant priming to neutral word pairs. Neither schizophrenic group showed direct priming with positive and negative word pairings, the deluded subjects showing inhibition of priming with negative stimuli. Controls failed to show direct priming with negative stimuli. Indirect priming was obtained in all groups. The absence of direct priming and indirect priming with negative material in deluded subjects was particularly striking. The results point to quantitative and qualitative abnormalities in semantic networks in schizophrenia. Conclusions. We propose that delusions may be the result of intact, unusual (indirect) associations in contrast to poorer normal (semantic) associations; a particular bias being shown toward material of a negative valence.