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Travis L Young, Allen L Nagy; Combining information about color and line length in visual search. Journal of Vision 2003;3(9):704. doi: 10.1167/3.9.704.
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© ARVO (1962-2015); The Authors (2016-present)
Previous research in our lab has shown that observers can combine information in different cardinal color mechanisms to facilitate search and supports a non-linear model of the information combination. In the present experiments we investigated whether information about color and line length could be combined to facilitate search. Observers searched for a single longer line among distractor lines subtending a visual angle of 0.47 deg. in a brief display. A spatial 2AFC procedure was used to estimate thresholds for detecting the longer line. Either 2 or 10 stimuli were presented with half to the left and half to the right of fixation. The observer indicated whether the longer line appeared to the left or the right. In uniform conditions all lines within a display were the same chromaticity, and were green, white, or red in different experiments. In the variable conditions 2 target lines (1 to the left and 1 to the right) of known color were presented among 8 distractors. One of the target lines was longer than the other 9 lines. A cue informed the observer of the target line color for each block of trials. Targets were saturated green, desaturated green, or white. Distractors differed from the targets in color and varied in appearance from green to red in each display. Results from the uniform conditions show that line color had no effect on thresholds, but thresholds for 10 stimuli were 2.3 times higher than thresholds for 2 stimuli. In the variable conditions thresholds were lower than in the uniform condition with 10 stimuli for saturated green and white targets, but not for desaturated green targets. Results show that information about color and length can be combined to facilitate search in some cases, and are consistent with a linear model of the information combination rather than the non-linear model that described the combination of information in different cardinal color mechanisms.
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