The goal of our research program is to identify highly specific, low-level building blocks of cognition that are impaired in schizophrenia (SZ) and are linked both with the underlying neurobiology of the illness and with broad measures of higher cognitive function. Such cognitive processes need to be (a) simple enough to be understood neurobiologically; (b) substantially impaired in SZ; and (c) tightly linked to performance on complex cognitive tasks. We propose that the ability to simultaneously represent multiple pieces of information (e.g., multiple objects, multiple locations)-which underlies working memory capacity and plays a key role in many cognitive tasks-meets these criteria. We have developed both behavioral and electrophysiological methods for measuring the ability to represent multiple objects or locations, and have shown that this ability is impaired in SZ and is strongly correlated with performance on complex tests that predict functional outcome in SZ (MATRICS and WASI). Moreover, computational neuroscience research has shown that local circuit abnormalities in SZ may lead to exaggerated winner-take-all processing that would interfere with the ability to maintain multiple simultaneous representations. Thus, by understanding why SZ patients exhibit a deficit in this low-level cognitive building block, we will be able to build a bridge from local circuit abnormalities in SZ to the impairments in broad cognitive functioning that influence functional outcome. Our Aims are designed to advance our understanding of the origins of reduced working memory capacity in SZ (Aim 1); test the hypothesis that exaggerated winner take all processing impacts attention across a range of tasks (Aim 2); test the hypothesis that the ability of maintain multiple representations can be linked to local circuit abnormalities may be indexed by gamma-band EEG oscillations and lateral sensory interactions (Aim 3), to develop computational models of local circuit abnormalities that can account for observed performance in patients (Aim 4) and to examine the same processes in a group of non-psychotic first degree relatives to determine if the abnormality observed in patients may represent a genetic risk factor for the illness (Aim 5). One important feature of our hypothesis is that it leads to the predictionof either fully normal or supranormal performance among patients in task environments where an excessively narrow focus of attentional selection should benefit performance, thereby potentially avoiding the interpretive problem posed by the generalized cognitive deficit that patients often demonstrate. Relevance: The working memory deficits in SZ are substantially related to impairments in complex cognitive operations that limit daily functioning. This research program is designed to increase understanding of the specific processes that are involved in the genesis of these deficits, providing the field with a computational framework to guide basic research, an important biomarker for treatment development as well as potentially valuable clinical assessment tools.