Failure to benefit from target novelty during encoding contributes to working memory deficits in schizophrenia.

INTRODUCTION: Although working memory (WM) impairments are well documented in schizophrenic patients (PSZ), the underlying mechanisms are poorly understood. The aim of this study was to investigate the role of target salience during encoding to determine whether impaired visual attention in PSZ leads to poor WM.
METHODS: Thirty-one PSZ and 28 demographically matched healthy controls (HC) performed a spatial delayed-response task. Attentional demands were manipulated during WM encoding by presenting high salient (novel) or low salient (familiar) targets. Participants also rated their level of response confidence at the end of each trial, allowing us to analyse different response types.
RESULTS: WM was impaired in PSZ. Increasing target salience by increasing novelty improved WM performance in HC but not in PSZ. Poor WM performance in PSZ was largely due to an increase in the proportion of incorrect but high confident responses most likely reflecting a failure to encode the correct target.
CONCLUSIONS: Our findings suggest that dysfunctions of non-mnemonic attentional processes during encoding contribute to WM impairments in schizophrenia and may represent an important target for cognitive remediation strategies.