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Travis L. Young, Satomi Amster, Allen L. Nagy; Combining spatial information and color in a visual search task. Journal of Vision 2004;4(8):680. doi: 10.1167/4.8.680.
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© ARVO (1962-2015); The Authors (2016-present)
Previous research in our lab has shown that if observers are cued about color of a target stimulus they can combine color information with line length information to facilitate detection of a target line that is longer than distractor lines. In this experiment we reversed the roles of color and length information. We asked if observers could combine cued length information with color information to facilitate detection of a line that differs in color from distractor lines. Four observers searched for a line of cued length that differed in redness (L chromaticity) from white distractor lines that varied in length. Ten stimuli were presented with half on each side of fixation. Two stimuli of the cued length were presented among 8 other lines. A spatial 2AFC procedure was used to estimate thresholds for detecting the redder line. A cue informed the observer of the length of the target for each block of trials. The observer indicated whether the redder target line appeared to the left or the right. Thresholds in this heterogeneous condition were compared with thresholds in homogeneous conditions in which all lines were the same length and set size was either 2 or 10. Results showed that thresholds increased with set size in the homogeneous conditions. In all conditions, thresholds decreased slightly as line length increased. Thresholds in the heterogeneous conditions were slightly smaller than thresholds in the homogeneous condition and a set size of 10, but larger than thresholds with a set size of 2. Results from a second experiment with line orientation as the cued spatial dimension were similar to results in the first experiment. We conclude that cued spatial information cannot be combined efficiently with the chromatic information to facilitate detection of the chromatic target. Results differ from those obtained in earlier experiments when cued color information was combined with length information effectively to facilitate detection.
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