The construct of attention in schizophrenia

Schizophrenia is widely thought to involve deficits of attention. However, the term "attention" can be defined so broadly that impaired performance on virtually any task could be construed as evidence for a deficit in attention, and this has slowed cumulative progress in understanding attention deficits in schizophrenia. To address this problem, we divide the general concept of attention into two distinct constructs: input selection, the selection of task-relevant inputs for further processing; and rule selection, the selective activation of task-appropriate rules. These constructs are closely tied to working memory, because input selection mechanisms are used to control the transfer of information into working memory and because working memory stores the rules used by rule selection mechanisms. These constructs are also closely tied to executive function, because executive systems are used to guide input selection and because rule selection is itself a key aspect of executive function. Within the domain of input selection, it is important to distinguish between the control of selection-the processes that guide attention to task-relevant inputs-and the implementation of selection-the processes that enhance the processing of the relevant inputs and suppress the irrelevant inputs. Current evidence suggests that schizophrenia involves a significant impairment in the control of selection but little or no impairment in the implementation of selection. Consequently, the CNTRICS (Cognitive Neuroscience Treatment Research to Improve Cognition in Schizophrenia) participants agreed by consensus that attentional control should be a priority target for measurement and treatment research in schizophrenia.