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Darren E. Koenig, Heidi J. Hofer; Does Reporting Color Facilitate Detection In A Threshold-level, Dual-judgment Task?. Invest. Ophthalmol. Vis. Sci. 2011;52(14):4900.
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To assess the interaction between detection and appearance judgments for small, threshold foveal stimuli, specifically whether requiring subjects to monitor and report color appearance induces criterion shifts or facilitates detection compared with a detection-only task.
Four subjects viewed brief (6 msec), monochromatic (580 nm), small spot stimuli (~1’) at 4 intensity levels (including blanks) presented to the dark-adapted fovea. Subjects were instructed to rate either detection certainty (rating scale 1-5), color appearance (10 point ‘hue’ scale, categories: red, yellow, green, blue, and white) or both, in randomly interleaved blocks of 80 trials for a total of 500-1300 trials per response condition. Subjects practiced until ratings use was consistent (practice trials were excluded from analysis).
Despite the increased cognitive burden and task complexity, reporting color appearance in addition to detection certainty does not elevate thresholds. For 3 subjects (1 naïve, 2 experienced) thresholds in the dual-report condition were lower than when reporting detection certainty alone. Increased discriminability and decreased false positive rates in the dual-report condition indicate a facilitatory effect. For one subject, limiting response rate in a detection-only experiment elevated rather than lowered thresholds, implying results were not due to the effective reduction in response rate imposed by the dual-report requirement.
Response complexity, divided attention, and suboptimal perceptual recall may be expected to negatively impact thresholds when subjects are required to simultaneously report color appearance during a detection task. Surprisingly, our results showed some subjects perform significantly better when asked to do just that. Lower thresholds were accompanied by increased discriminability, not increased false positive rates, as if enhanced endogenous attention when reporting color allows access to otherwise unavailable information. These results suggest that 1. color mechanisms contain information relevant for detection at cone threshold, and 2. subjects are not able to voluntarily marshal the attentional or motivational resources to make full use of this information in a simple detection task.
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