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Amira A. Rezec, Bart Krekelberg, Karen R. Dobkins; Effects of contrast and attention on chromatic vs. achromatic motion processing. Journal of Vision 2004;4(8):553. doi: 10.1167/4.8.553.
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© ARVO (1962-2015); The Authors (2016-present)
PURPOSE: Directing attention toward a stimulus enhances motion processing for various types of motion stimuli and tasks. It has been suggested that attention may play a greater role for chromatic (red/green), than for achromatic (black/white), motion processing. To investigate this possibility, we measured the effect of attention on the duration of the motion after-effect (MAE) over a range of cone contrasts for both chromatic and achromatic stimuli. METHODS: Stimuli were achromatic or isoluminant chromatic sine wave gratings presented at 8 different cone contrasts (3–25%). For each stimulus contrast, MAE duration was obtained for two conditions: 1) Full Attention- subjects were instructed to attend to the adapting motion stimulus, and 2) Poor Attention- subjects were instructed to perform an attentionally demanding vowel detection task in the center of gaze during adaptation. Thus, subjects' attention to the adapting stimulus was greatly diminished in condition #2. In both conditions, a dynamic test stimulus was presented after 30 seconds of adaptation. Subjects responded with a key press to indicate when the MAE was no longer perceived. RESULTS & CONCLUSIONS: The influence of attention on MAE duration for chromatic and achromatic stimuli was very similar (1.4 fold) and constant over all stimulus contrasts. Hence, for these stimuli and with the MAE duration as a measure of motion strength, chromatic motion does not appear to rely more on attentional processing than achromatic motion.
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