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Orienting of Visual Attention Based on Peripheral Information

by Kean, Matthew Raymond

Abstract (Summary)
Restricted Item. Print thesis available in the University of Auckland Library or available through Inter-Library Loan. The spatial cueing technique (see M. I. Posner, 1980) was employed across five experiments to examine the orienting of visual attention in response to peripherally-presented information. In each experiment, peripheral cues conveyed useful information regarding the likely location of an impending target, and participants were informed of this probabilistic relationship. The primary dependent variable was the latency to initiate a saccadic eye movement to the target stimulus. In Experiment 1, identical bilaterally- and simultaneously-presented cue stimuli symbolically communicated the target's likely location. The slow time course of effective orienting in this situation - i.e., at the stimulus onset asynchrony (SOA) of 600 ms - points to the operation of the endogenous orienting mechanism. The bilateral cue stimuli in Experiment 2 differed from each other with respect to their identities (X versus T). Successful orienting was observed across a range of SOAs (zero, 100, 300, & 600 ms) when X was the valid indicator of the target's location, but no orienting was observed when T was valid. This disparity suggests that the identity of the cue letters may have been confounded with their respective levels of salience. In Experiment 3, bilateral cue stimuli were presented that shared the same identity but differed with respect to luminance levels, and only brief SoAs were employed (zero, 50, 100, & 150 ms). Attention was rapidly (across the two shortest SOAs) attracted to the location of the most salient cue when the cue stimuli were uninformative. This exogenous attention-capturing effect of the bright cue was significantly attenuated when the dim cue was the valid indicator of the target's likely location, and when the bright cue was valid. In Experiment 4, the location of a highly salient unilateral cue communicated the likely target location. Given long SOAs (300 & 600 ms), participants could readily direct attention away from the cue when its location rarely corresponded with that of the target, but could not endogenously maintain attention at the cued location when the target was expected there. At the brief SOA of 100 ms, results evidenced successful orienting both towards and away from the cue, depending on the cue-target contingency. The latter observation was replicated in Experiment 5, which also indicated that the brief SOAs of 33 and 67 ms are not conducive to effective orienting away from a salient cue. Taken together, results indicate that peripheral information is an important factor influencing attentional orientation. It is argued that attention capture is not the only process capable of activating the attentional response system via a bottom-up pathway.
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Advisor:

School:The University of Auckland / Te Whare Wananga o Tamaki Makaurau

School Location:New Zealand

Source Type:Master's Thesis

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Date of Publication:01/01/2003

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