Carrasco, M. & Yeshurun, Y. (1998). The contribution of covert attention
to the set-size and eccentricity effects in visual search. Jrnl
of Exptl Psych, 24(2): 673-692.
To reexamine the role of covert attention in visual search, the
authors directly manipulated attention by peripherally cueing the target
location and analyzed its effects on the set-size and the eccentricity
effects. Observers participated in feature and conjuction tasks. Experiment
1 used precues, and Experiment 2 used postcues in a yes-no task under
valid-, invalid-, and neutral-cueing conditions. Experiments 3 and 4 used
a 2-interval forced-choice visual-search task under cued and neutral conditions.
Precueing the target location improved performance in feature and conjunction
searches; postcueing did not. For the cued targets, the eccentricity effect
for features and conjunctions was diminished, suggesting that the attentional
mechanism improves the quality of the sensory representation of the attended
location. The conjunction set-size effect was reduced but not eliminated.
This questions serial-search models that attribute a major role to covert
attention in visual search.