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David Bridwell, Sam Thorpe, Ramesh Srinivasan; The influence of goal-directed attention on unattended stimulus-driven responses. Journal of Vision 2010;10(7):156. doi: 10.1167/10.7.156.
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Attention is influenced by internal goals and external stimulus-driven events. In the following experiment we investigate how peripheral goal-directed attention to one visual field modulates the steady-state visual evoked potential (SSVEP) to a flickering noise patch in the opposite visual field. In the experiment, goal-directed attention is shaped by conditions that emphasize 1) enhancement of external noise at the attended location (by detecting changes in external noise contrast) 2) suppression of external noise at the attended location (by detecting a Gabor patch within high external noise), and 3) neither suppression nor enhancement of external noise in the attended location (by detecting a Gabor patch within low external noise). SSVEP responses to the unattended noise flicker allow us to examine how suppression and enhancement of external noise at the attended location may modulate the response to external noise at an unattended location. SSVEP responses to the flickering (f2 = 8 Hz) unattended noise were measured across 40 second trials and Fourier analyzed. We found a patch of occipitoparietal electrodes contralateral to the attended location (ipsilateral to the flicker) that were significantly larger when individuals detect changes in noise contrast at the attended location (condition 1 vs. 2). During Gabor detection within high and low noise (condition 2 vs. 3) we find no significant difference in occipitoparietal responses. These results indicate that 8 Hz occipitoparietal responses to an unattended noise flicker increase when top-down goals match features of the unattended flicker. These occipitoparietal responses do not decrease when top-down goals promote suppression of features at the attended location. The results are consistent with findings suggesting that peripheral attention suppresses external noise primarily at the attended location (Lu, Lesmes, & Dosher, 2002, Journal of Vision) while feature enhancement extends to unattended locations.
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