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Kelly E Neriani, Allen L Nagy; Combining information in different color mechanisms in visual search. Journal of Vision 2003;3(9):705. doi: 10.1167/3.9.705.
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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. The purpose of this study was to investigate the efficiency for combining information. A yes-no task was used in all experiments. Stimuli were small disks that differed in luminance from a uniform gray background. Disks were presented for 200 msec within an annular region centered on a fixation point. In preliminary experiments we determined psychometric functions for detecting a white target stimulus among distractors that differed in L chromaticity and matched in S chromaticity. Nine stimuli were presented on each trial. These data were used to estimate L chromaticity differences in the red and green directions that corresponded to 98% correct. In the primary experiments we determined thresholds for detecting an increment in the S chromaticity of the white stimulus. In one condition the white stimulus was presented among 4 red and 4 green distractor stimuli set to the chromaticity differences determined in the preliminary experiments or to one half these chromaticity differences. S thresholds in these conditions were compared with S thresholds when all 9 stimuli were white and also when only 2 white stimuli were presented on each trial. Results showed that when the white stimulus was presented among red and green distractors, S thresholds were lower than when all 9 stimuli were white, suggesting that information in the L and S cardinal mechanisms was combined to facilitate performance. Furthermore, when the chromaticity differences were set to the level corresponding to 98% correct, thresholds were lower than when only 2 white stimuli were presented on each trial. We conclude that there is little or no information lost when information in different cardinal color mechanisms is combined. Similar experiments will be reported for luminance and chromaticity information.
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