It is well known that attention can improve performance in a variety of tasks. A crucial unsettled issue is whether this improvement is due to noise reduction (internal or external), a change in decisional criteria, features binding, or signal enhancement. By combining peripheral precues with Visual Search (Chapter 1), Acuity, and Hyperacuity (Chapter 2) tasks we show that attention improves performance by signal enhancement. Specifically, we claim that attention increases the spatial resolution at the attended location.
The use of a texture segregation task in which performance is actually diminished due to enhanced spatial resolution provides the principal evidence for this claim (Chapter 3). We observed that attention improved performance at peripheral locations where spatial resolution was too low, but impaired performance at central locations where spatial resolution was too high. The counterintuitive impairment of performance that we found at the central locations appears to have only one possible explanation: attention enhances spatial resolution. Further manipulations of the texture's spatial frequency indicated that these attentional effects reflect changes in second-order filters (Chapter 4).
