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Kyle C. McDermott, Jeffrey B. Mulligan, George Bebis, Michael A. Webster; Visual search in familiar contexts - effects of learning or adaptation?. Journal of Vision 2006;6(6):527. doi: 10.1167/6.6.527.
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Search times for detecting a novel color on a background of varying colors are faster when observers are previously exposed to the background colors. We examined whether this improvement reflects changes in color salience resulting from adaptation to the background vs. changes in search strategies or learning for familiar backgrounds. The target was an ellipse at a random location on backgrounds of overlapping ellipses. Target colors varied across trials over a wide range. The luminance and color of background elements varied randomly by sampling from different color distributions. In the first condition, we used selective distributions with colors confined to the LM or S cardinal axes. Subjects first viewed sequences of LM or S backgrounds for 2 min and then searched for targets on an LM or S background. Searches were monitored with a CRS eyetracker and terminated when the targets were fixated for 0.5 sec. Targets were located more quickly on the pre-exposed backgrounds. However, eye movements patterns (e.g. fixation durations and saccade lengths) did not differ across the two backgrounds, suggesting that sampling strategies remained similar. In a second condition, we measured search on a nonselective color distribution drawn from a circle of hues at fixed contrast. Prior exposure to this background did not facilitate search for novel contrasts relative to an achromatic adapting background, suggesting that subjects were not simply learning the background distributions. Instead, results for both conditions are consistent with a selective adaptation effect that enhances the salience of novel stimuli by discounting the background.
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