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Abstract:
This research investigates the role of spatial attention in
target localization. Hazeltine et al. (1997) used a task that
required subjects to first localize a green target letter among a
row of non-green letters, and then indicate whether or not the
green letter was an "O". On some trials, there was a non-green "O"
present with a green target which was not an "O". An illusory
conjunction of color and form occurred if a green "O" was reported
on this type of trial. The distributions of localization errors
were similar for trials with illusory conjunctions and trials with
veridical perceptions, except that the center of the distribution
for illusory conjunctions was shifted halfway between the green
target and non-green "O". In the present research, we use a spatial
cue with the Hazeltine et al. procedure to examine the role of
spatial attention in object localization. Subjects were cued to the
location of the letter row with either a spatially uninformative
exogenous cue or a spatially informative endogenous cue.
Localization accuracy was greater and illusory conjunctions were
fewer for attened letter rows than unattended letter rows, but the
distributions of localization errors were not affected. The role of
spatial attention in the perception of visual space and in the
construction of veridical percepts is discussed.
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