Frieder, K, & Carrasco,
M (2001, May). Negative priming for unfamiliar shapes occurs under covert
attention. Vision ScienceS Society, Sarasota, FL. 211-B11.
Introduction and Goal: In this study, for the first time, we explored
whether the selective processing of an unfamiliar shape at the attended
location is influenced by information outside the locus of attention even
when the short duration of the display precluded eye movements. We examined
the effects of a distracter in the unattended hemifield on the processing
of the target in the attended hemifield.
Method: To test the effect of unattended items, we employed a modified
Negative Priming (NP) task that required a symmetry judgment of a target.
Observers viewed a series of displays with a pair of overlapping shapes
(a lateralized green target was overlapping a red distracter). Observers
had to determine whether the target was symmetrical or not. Experimental
trials were paired so that a "Prime" trial was followed by a "Test" trial.
Following a negative priming paradigm, unbeknownst to the observers, in
the Priming Condition, the red overlapping-distracter in the Prime trial
re-appeared as the green target in the following Test trial. In the Control
condition, al the shapes were novel. In Condition 1, nothing appeared
in the opposite hemifield; in Condition 2 an additional black shape appeared
contralaterally. RTs and errors were analyzed.
Results and Conclusion: For the first time, we report a highly significant
NP effect for unfamiliar shapes under cover attention. More specifically,
RTs and errors were higher when the target was seen previously as the
overlapping-distracter than when the target was novel. Surprisingly, even
when the display was presented for less than 200ms, participants processed
the task-irrelevant overlapping-distracter, in all three conditions. Thus,
NP for unfamiliar shapes occurs under covert attention.