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Raúl Luna, Ignacio Serrano-Pedraza; Duration thresholds for motion discrimination of complex stimuli show non-linear interactions between motion sensors. Journal of Vision 2017;17(10):604. doi: 10.1167/17.10.604.
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© ARVO (1962-2015); The Authors (2016-present)
Previous research has shown that motion direction discrimination for complex stimuli composed of fine and coarse scales is impaired when both components move together at the same speed (Serrano-Pedraza, Goddard & Derrington, JoV, 2007). This increment of duration thresholds for motion discrimination was higher if the contrast of the coarse-scale component was lower than the contrast of the fine-scale component (Luna & Serrano-Pedraza, 2016, VSS). Here we performed two experiments where we used Bayesian staircases to measure duration thresholds for motion discrimination. In the first experiment we tested whether the relative phase of coarse- and fine-scale components (vertical-Gabor patches) had an effect on duration thresholds that could explain the impairment in motion discrimination. In the second experiment we tested complex stimuli composed of two Gabor patches of different spatial frequencies and same contrast (28%). Two types of stimuli were used: simple horizontally drifting vertical-Gabor patches and complex vertical-Gabor patches resulting from the addition of two Gabor patches of different spatial frequencies. We tested spatial frequencies ranging from 0.25 to 6c/deg and 20 different combinations between them. Results from the first experiment show that duration thresholds were independent of the relative phase of the components of the complex stimuli. The second experiment shows that a) duration thresholds decrease with increasing spatial frequency from 0.5 to 6c/deg; b) duration thresholds for complex stimuli were always larger than those for the higher spatial frequency component; and c) when the lowest frequency of the pair was 0.25c/deg, duration thresholds were shorter than for 0.25c/deg presented alone. Our results are in agreement with previous results that suggest a nonlinear interaction between motion sensors tuned to coarse and fine scales.
Meeting abstract presented at VSS 2017
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