The Effect of Attentional Load on Object Recognition and Individuation in Peripheral Vision

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 (Scolari, Kohnen, Barton, & Awh, 2007; Yeshurun & Rashal, 2010). The current study is based on last year research and suggests 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, multiple object tracking (MOT) at the center of the visual field was used: participants either have to track three 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 with staircase procedure. It was expected that attentional load under MOT would impair the recognition of the target ring both when the target was presented alone or when it was flanked. However, results support niether the role of central attention in individuation process nor in a clear recognition of peripheral stimulus.