Abstract
The function of visual dominance is basically unknown. Mapp et al. (2003) argue that eye dominance does not play a role in vision, and eye dominance may be attributed differently when using different defining tests (Walls 1951, Friedlander 1971, Pointer 2001). It is well known that an element which differs significantly from surrounding elements in a single dimension, such as orientation, pops-out and search performance is independent of the number of distractors (Treisman & Gelade, 1980). We evaluated eye dominance effects on performance of a feature search task. 13 subjects participated in the experiment; each had similar visual acuities in their two eyes. Dominant eye was determined several times, using the Hole-in-the-Card test (Durand & Gould 1910).
Subjects viewed through red-green glasses, an array of green and red lines oriented at 60°, followed by a masking stimulus after a variable Stimulus-to-mask Onset Asynchrony (SOA). On some trials, one element was replaced by a red or green line oriented at 40° - the target. The 8 nearest neighbors surrounding the target had the same color as the target, the opposite color, or a mixture of the two colors. Line colors were adjusted so that through the red-green glasses one eye saw only the red and the other the green lines - and both were perceived as black. In this way, we were able to test for differences in performance when subjects detected the target with the dominant vs. the non-dominant eye, and to test dependence on which eye viewed the surrounding elements.
We found significantly better performance when the target was seen by the dominant eye, especially when the surrounding elements were seen by the non-dominant eye. We conclude that there is an interaction between the salience arising from the pop-out and the dominance phenomenon. The advantage of the dominant eye may be in its perceiving items as if with more salience while items perceived by the non-dominant eye are relatively inhibited.
Supported by an Israel Science Foundation “Center of Excellence” grant and the US-Israel Binational Science Foundation (BSF).