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Christophe Carlei, Dirk Kerzel; Visual search for shape singletons as a function of visual hemifield. Journal of Vision 2015;15(12):1364. doi: 10.1167/15.12.1364.
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© 2017 Association for Research in Vision and Ophthalmology.
Asymmetries between left and right as well as upper and lower visual hemifield were investigated using pop-out search. Participants searched for a shape singleton and reported the orientation of a line segment inside the shape singleton. The target’s line orientation did not pop out, whereas its shape did. Our results showed that participants were faster to respond when targets were presented in the right compared to the left visual hemifield, which is opposite to a previous report that parallel search is better in the left visual hemifield (Poynter & Roberts, 2012). Our findings are also at odds with the idea that “global” or low-resolution processing is enhanced in the left visual field, which would predict faster singleton search on the left. Possibly, the requirement to report the line orientation inside the shape singleton implied “local” or high-resolution processing, which is supposed to be better in the right visual field, where we found reaction times to be shorter. Moreover, we also found shorter reaction times in the lower compared to the upper visual hemifield, which is consistent with previous reports of enhanced visual acuity in the lower visual hemifield. In sum, our findings show that both laterality and elevation affect reaction times in search for a shape singleton. Because our task required participants to report a visual detail after parallel search, presentation of shape singletons in the right and lower hemifields, which favor high-resolution processing, results in better performance.
Meeting abstract presented at VSS 2015
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