Shared lexical-semantic features and the animacy effect in early-course psychosis

Language deficits in psychosis, and in schizophrenia, are presumed to be due to increased activation and connectivity of the semantic memory, which is determined by lexical-semantic features of concepts. The aim of this study was to analyse the influence of shared lexical-semantic features on language processing in patients with first-episode and early-course psychosis. The study included 15 Croatian-speaking patients from the University Psychiatric Hospital Vrapče, Zagreb, diagnosed with first-episode and early-course psychosis and a healthy control group. The subjects performed a lexical-semantic decision task in which the primes and the target words were either related as hypernym and hyponym or were unrelated, and in which the target words represented either animate or inanimate concepts. Two results analyses were conducted: one on the taxonomic (hyponym–hypernym) condition and one on the animacy (living/non-living stimulus) condition. The patient group was less accurate on the taxonomy condition because the taxonomy relations were dependent on their shared features. The patients’ activation of shared features was higher, and their inhibition was reduced. Consequently, the patients will have a greater number of concepts activated and not inhibited. For the inanimate concepts, a high correlation of distinctive features is characteristic, while the animate concepts have a high correlation of shared features. The presupposition is that the greater activation of shared features influenced the patients’ answers, so the distinctive features had no influence. Thus, the control group had higher accuracy for inanimate concepts.