Effects of attention and working memory on perception
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Selective attention refers to perceptual selection and working memory refers to the active maintenance of mental representations. Selective attention and working memory are believed to be two of the most important functions in human cognition and have been intensively investigated in cognitive psychology. However, it is quite recent that the link between attention and working memory has been systematically researched. One question that remains controversial is the effect of working memory on attentional control with inconsistent results reported in the human psychophysical literature, despite clear and strong evidence from physiological studies with nonhuman primates that working memory is the main source of top-down attentional control. The main goal of the current study is to provide a plausible solution to the puzzle of attentional control by introducing the concept of goal-specificity and competition between working memory representations. I hypothesized that the strength of the biasing effect of working memory on attention depends on the specificity of representations in working memory, and developed an experimental paradigm (the goal-specificity paradigm) to test this hypothesis using psychophysical and neuroimaging methods. One of the most important manipulations in the goal-specificity paradigm is how specifically targets in different tasks are defined. The results demonstrate that there is competition between items in working memory for attentional control that is influenced by the specificity of each representation as well as task relevancy. Also, it is shown that the effect of goal-specificity is present in both spatial and temporal domains as revealed by visual search and rapid serial visual presentation tasks. The results suggest the possibility that the negligible effect of working memory in some previous studies may be due to insufficient specificity of the objects in working memory or to the presence of other specifically-defined information in working memory. Furthermore, based on the implication from the current study that goal-specificity has a significant influence on attentional control, I expect that the experimental paradigm introduced in the current study can be utilized as an objective psychophysical measure of attentional control.