Carrasco, M. & Loula (2001).
Effects of selective adaptation on testure segmentation and its interaction
with covert attention. Vision ScienceS, Sarasota, Florida.
Introduction. In a texture segmentation task where perfromance peaks at
mid-peripheral locations, the performance drop near the fovea is usually
attributed to the spatial filters at the fovea being too small for the
scale of the texture. Yeshurun and Carrasco (1998, 2000) found that attending
to the target location improves performance where the resolution is already
too high (central locations) for the task. These results indicate that
attention enhances spatial resolution.
Goal. To investigate further the spatial properties underlying the central
performance drop in texture segmentation, and to further characterize
the attentional effect. For the first time, we combine selective adaptation
and precue procedures.
Method. In a 2IFC task (which interval contained a target) observers were
presented with a precue that indicated either both target location and
display onset (peripheral cue) or just display onset (neutral cue). The
target patch appeared at varying eccentricities in a large texture pattern
along the horizontal meridian. Observers adapted for 8 min to a display
containing either a high- (8 cpd) or a low- (1 cpd) spatial frequency
sinusoidal grating. Immediately after, they performed 250 trials of the
texture segmentation task. The same adaptation pattern was presented for
1 sec before each trial, to 'top-up' and maintain the initial adaptation
Results and Conclusion. In the neutral condition, adapting to the 1-cpd
grating produced similar functions for performance at the peripheral and
at the central locations. However, adapting to the 8 cpd grating diminished
the central performance drop. Furthermore, after adapting to the 8-cpd
grating we found no attentional impairment at the central locations. These
results support conclusively the spatial nature of the central performance
drop and advance our knowledge of the way that attention enhances spatial