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Joseph Nah, Marco Neppi-Modona, Lars Strother, Marlene Behrmann, Sarah Shomstein; The Effect of Object Size in Object-Based Attentional Selection. Journal of Vision 2017;17(10):1337. doi: https://doi.org/10.1167/17.10.1337.
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© ARVO (1962-2015); The Authors (2016-present)
While decades of research has provided evidence that within-object attentional shifts are faster than between-object shifts, most evidence is drawn from studies employing two objects that are identical in size. Thus, it remains unclear whether the size of an object influences attentional shifts within- and between-objects. Here, in a set of four experiments (3 behavioral and 1 eye-tracking), we manipulated the width of an object in a modified version of the classic two-rectangle paradigm by Egly et al. (1994). Participants were presented with one of three possible displays: (1) two identical parallel rectangles of two mixed widths (thin, thick), (2) two identical trapezoids (having both a thin and a thick end) that were inverted in orientation, or (3) two perceptually different yet physically identical parallelograms achieved by utilizing a variant of the famous Shepard's Table illusion. One end of an object was cued and participants performed a T/L discrimination or a target detection task, depending on the experiment. Combined results show that, in addition to the standard object-based effects, shifting attention within or between 'thick' objects or toward the 'thick' end of objects, resulted in significantly faster response times (RT) than the corresponding shifts of attention involving 'thin' objects or 'thin' object parts. The results were replicated with target detection tasks, providing evidence against a possible crowding explanation (targets in thin objects are detected more slowly because object edges are crowding the target). Additionally, object-based effects were replicated using eye-tracking measures (i.e., total number of saccades, saccade duration, saccade amplitude, peak velocity). Importantly, size effects were not observed in eye-tracking measures, providing further evidence against possible crowding effects. Taken together, these results suggest that deployment of object-based attention is modulated by properties of the object, such as its width; and that size affects attentional rather than motor processing
Meeting abstract presented at VSS 2017
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