Abstract
We can effortlessly focus on and compare separate items, even when part of different objects. Here, we ask whether establishing new links between items is enough to consider such items, or whether it is also necessary to build a more complex representation that integrates these new links with groups issued from automatic grouping, thus helping to preserve the stability of background information. We explore this question by studying how such processes are disturbed in patients with schizophrenia (N=43) relative to controls (N=43). In a perceptual task (derived from Beck & Palmer, JEP:HPP 2002), subjects have to find two identical and adjacent figures displayed among six different objects arranged on a circle. Targets are either connected by a line (within-group pairs), or are unconnected but belong to different groups (between-group pairs). It is easier to find targets when they belong to the same rather than to different groups, but this advantage is reduced when between-group trials are more frequent. In contrast with controls, patients with schizophrenia show an advantage for between-group trials, and an impairment in finding within-group targets when incited to prioritize between-group trials (i.e. when those trials are more frequent). Else they show a preserved advantage for within-group pairs. A similar result is observed when the task is adapted to explore memory. The results show that patients are able to establish links between separate, between-group figures when forced to do so. Automatic grouping also seems preserved in usual conditions, and even if such grouping is fragile, it could explain a loss but not a reversal of the advantage for within-group pairs. It is thus rather the integration of the two types of pairs in a single representation that seems to be impaired in patients, showing that establishing links between separate items is not enough to flexibly explore the environment.