Salient collinear grouping diminishes local salience in visual search: An eye movement study

Our eyes and attention are easily attracted to salientitems in search displays. When a target is spatiallyoverlapped with a salient distractor (overlapping target),it is usually detected more easily than when it is not(nonoverlapping target). Jingling and Tseng (2013),however, found that a salient distractor impaired visualsearch when the distractor was comprised of more thannine bars collinearly aligned to each other. In this study,we examined whether this search impairment is due toreduction of salience on overlapping targets. We usedthe short-latency saccades as an index for perceptualsalience. Results showed that a long collinear distractordecreases perceptual salience of local overlappingtargets in comparison to nonoverlapping targets,reflected by a smaller proportion of the short-latencysaccades. Meanwhile, a salient noncollinear distractorincreases salience of overlapping targets. Our results ledus to conclude that a long collinear distractor diminishesthe perceptual salience of the target, a factor whichposes a counter-intuitive condition in which a target on asalient region becomes less salient. We discuss thepossible causes for our findings, including crowding, theglobal precedence effect, and the filling-in of a collinearcontour.