Abstract
Crowding is a phenomenon of peripheral vision that impairs the ability to individuate (perceptually separate objects from each other) and, as a result, to recognize an object surrounded by flankers (Intriligator & Cavanagh, 2001; Whitney & Levi, 2011). There is a long-living controversy in the literature between theories supporting or denying the role of attention in crowding (Yeshurun & Rashal, 2010; Scolari et al., 2007). In our study, we suggest a new experimental approach to addressing this issue. It is based on a dual-task paradigm allowing to manipulate attentional allocation towards or away from the crowded stimuli. As a primary task to manipulate attentional load, we used multiple object tracking (MOT) at the center of the visual field: participants either tracked few moving targets among 8 items (load), or passively observed motion (no load). The crowding task was secondary and required observers to recognize the orientation of a Landolt's ring, surrounded by two flanker rings (crowding) or alone (control). To keep the rings at fixed eccentricity, observers performed MOT looking at fixation and were eye-tracked. Both the optimal difficulty of MOT and the baseline crowding threshold (critical target-flanker distance) were measured for each individual observer. Our results show attentional load under MOT impaired the recognition of the target ring both when this target is presented alone (under load: M = 78.03% vs no load: М = 92.5%) or when it is flanked (under load: М = 56.4% vs no load: М = 66.5%) which indicates the general role of attention in extrafoveal vision. As load-induced decrements in the recognition rate were approximately equal in the crowded and the control conditions, we cannot draw a strong conclusion regarding a specific effect of attention on recognition of an object surrounded by flankers and on crowding.
Meeting abstract presented at VSS 2018