Eye of origin guides attention away: An ocular singleton column impairs visual search like a collinear column

Abstract

Collinearity and eye of origin were recently discovered to guide attention: Target search is impaired if it is overlapping with a collinear structure (Jingling & Tseng, 2013) but enhanced if the target is an ocular singleton (Zhaoping, 2008). Both are proposed to occur in V1, and we study their interaction here. In our 9 × 9 search display (Experiment 1), all columns consisted of horizontal bars except for one randomly selected column that contained orthogonal bars (collinear distractor). All columns were presented to one eye except for a randomly selected column that was presented to the other eye (ocular distractor). The target could be located on a distractor column (collinear congruent [CC]/ocular congruent [OC]) or not (collinear incongruent [CI]/ocular incongruent [OI]). We expected to find the best search performance for OC + CI targets and the worst search performance for OI + CC targets. The other combinations would depend on the relative strength of collinearity and ocular information in guiding attention. As expected, we observed collinear impairment, but surprisingly, we did not observe any search advantage for OC targets. Our subsequent experiments confirmed that OC search impairment also occurred when color-defined columns (Experiment 2), ocular singletons (Experiments 4 and 5), and noncollinear columns (Experiment 5) were used instead of collinear columns. However, the ocular effect disappeared when paired with luminance-defined columns (Experiments 3A and 3B). Although our results agree well with earlier findings that eye-of-origin information guides attention, they highlight that our previous understanding of search advantage by ocular singleton targets might have been oversimplified.

Collinear search impairment is luminance contrast invariant

“…In all reported cases of collinear search impairment (e.g. 20 , 21 , 42 ), the stimuli were high contrast (i.e. all well above the participants’ detection and discrimination thresholds).…”

“…A good candidate to account for the collinear search impairment is the collinear flanker effect. The early experiments examining collinear facilitation used a set of collinear bars 19 , similar to the collinear structure used by Chow et al 20 , 21 . The collinear flanker effect refers to the change in visual response to an oriented target in the presence of nearby oriented stimuli (flankers) that are collinear with the target.…”

“…Nevertheless, significant search impairment has been robustly reported, which indicates that the subjective awareness of a complete collinear structure is not required. Similarly, Chow, Jingling, and Tseng 20 used a singleton column defined by the eye-of-origin to provoke similar search impairment. As the participants were unable to identify the origin of the eye where the stimuli were displayed (i.e.…”