Abstract
We investigated the flexibility and adaptability of spatial covert attention in a texture segmentation task that is constrained by spatial resolution. In a study of transient attention and texture segmentation, Yeshurun & Carrasco (1998) found that precueing the target location improved performance in the periphery, where spatial resolution was too low for the task, but impaired performance at central locations, where spatial resolution was already too high. This counterintuitive central attentional impairment can only be explained by transient attention increasing spatial resolution, even when it is detrimental to performance. Such unidirectionality of the effect supports the automaticity of transient attention and suggests that it is not flexible. Here we investigated whether the voluntary and more controlled component of covert attention-sustained attention-can also affect spatial resolution and be more flexible, i.e., both increase and decrease spatial resolution to optimize performance at all eccentricities.
As previously found, in neutral trials performance peaked at mid-peripheral locations and dropped at farther peripheral and more central locations. Sustained attention aided performance at both central and peripheral locations; thus, in contrast to transient attention, it did not impair performance at central locations. This is consistent with the hypothesis that sustained attention can affect spatial resolution. The attentional effect varied as a function of both target eccentricity and texture scale. The benefit of sustained attention at all eccentricities suggests that it increased spatial resolution where it was too low (periphery), but decreased spatial resolution where it was too high (central locations). These results indicate that sustained attention is more flexible than transient attention, and are consistent with the idea that it can optimize performance by either enhancing or decreasing spatial resolution at the attended location.
Grant 25-91551-F5461 from the United States-Israel Binational Science Foundation (BSF)