Neural bottlenecks in concurrent multi-item visual search J Peters1, J Reithler1, R Goebel1, P Roelfsema2 |
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1Cognitive Neuroscience, Maastricht University, Netherlands |
| Psychophysical data suggest that concurrent visual search for two items is impossible, since only one item in working memory (WM) can function as search template at a time [Houtkamp and Roelfsema, 2009, Psychological Research, 73, 317–326]. Here, we studied the neural correlates of this multi-item search limitation using fMRI (3T, n=8, TR/TE = 1.25s/30ms). Participants had to detect a face or a house (uni-search), or a face and house (dual-search) in a stream of superimposed face and house images. Psychophysical results (n=16) confirmed that in the dual-search condition, the two target representations in WM could not guide attention simultaneously. This limitation was reflected in face- and house-preferring visual areas, where dual-search elicited lower responses than uni-search for the preferred category. In contrast, dual-search did induce stronger activation in a frontoparietal network involved in storage and control of items in WM. Our current investigations of the interaction between these frontoparietal and visual activations may provide more insights into the neural bottlenecks causing the limited capacity of attentional guidance by WM. |
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