<qa>  What is a hallmark characteristic of SZ?While a hallmark characteristic of SZ is neurocognitive impairment, these deficits notably overlap with the cognitive domains that are improved by caffeine. Among the core deficts observed within SZ is a dysfunction of attentional systems, which can be observed in patients who are both acutely psychotic and in remission. Deficits of attention in SZ include both alteration of sustained attention, particularly as measured by continuous performance tasks and visual selective attention Luck Gold, 2008, as measured by visual search tasks. It has further been suggested that within SZ these deficits of attention contribute to dysfunction of the central executive and working memory, the limited capacity system for storing and manipulating information for short time periods up to 30 s, in order to carry out complex cognitive operations such as planning, reasoning, and problem solving. Impairment in working memory processes, such as those indexed by the n-back task, are a robust feature of SZ, are stable over time, and independent of psychotic symptoms. 