| Three series of experiments discussed the impact of uncertainty reduction on attentional guidance and selection. First, uncertainty was examined in the context of object-based attention by manipulating the predictive power of a sensory cue. It was shown that when uncertainty is reduced with a highly predictive spatial cue, object-based effects were not present. This demonstrates that uncertainty is what determines selection. Second, uncertainty reduction was applied to a dynamic display to separate spatial locations from overlapping objects to determine which benefits from uncertainty reduction. It was demonstrated that with uncertainty, surfaces and spatial locations influence selection but when uncertainty was reduced, only spatial locations guided attention. Results suggest that uncertainty plays an important role in attentional selection and the focus of prioritization changes over time. Third, uncertainty reduction was applied to an internal signal by introducing reward. A significant reward effect was demonstrated with controls: search was structured so that the high rewarded targets were selected faster than low rewarded targets. Effects in neglect patients depended on lesion location: those with the putamen intact showed a sensitivity to reward (in either bottom-up or top-down orienting), and one showed a significant reduction of neglect. This series suggests that not only is an internal signal effective for attentional allocation, but that it can help to overcome an attentional deficit such as neglect. Overall, results from the three series suggest that uncertainty plays a vital role in attentional selection, in that it determines the most efficient way to allocate resources. |
