Crowding by a single bar E Poder |
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Institute of Psychology, University of Tartu, Estonia
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| Visual crowding does not affect much the detection of the presence of simple visual features but perturbs heavily their relative positions and combining them into recognizable objects. Still, the crowding effects have been rarely related to general pattern recognition mechanisms. In this study, pattern recognition in peripheral vision was probed using a single crowding feature. Observers had to identify the orientation (4AFC) of a rotated T presented briefly (60 ms) at a peripheral location (eccentricity 6 deg). Adjacent to the target, a single bar was presented. The bar was either horizontal or vertical, and located in a random direction (0-360 deg) from the target. It appears that such a crowding bar has very strong and regular effects on the identification of the target orientation. Certain combinations of relative position and orientation of the bar have little crowding effect while others deteriorate performance down to chance level. Different kinds of incorrect answers dominate for different combinations. It seems that responses are determined by approximate relative positions of features, exact image-based similarity to the target is not important. A simple model of pattern recognition is proposed that explains the main regularities of the data. [Supported by Estonian Ministry of Education, project SF0180027s12] |
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