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H. P. Snippe, L. Poot, J. H. van Hateren; Asymmetric dynamics of adaptation after onset and offset of flicker. Journal of Vision 2004;4(1):1. doi: 10.1167/4.1.1.
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We measured human psychophysical detection thresholds for test pulses which are superimposed on spatially homogeneous backgrounds that have abrupt onsets and offsets of high-contrast 25 Hz flicker. After the onset of the background flicker, test thresholds reach their steady-state levels within 20–60 ms. After the offset of the background flicker, test thresholds remain elevated above their steady-state level for much longer durations. Adaptation after onsets and offsets of background flicker is modeled with a divisive gain control that is activated by temporal contrast. We show that a feed-back structure for the gain control can explain the asymmetric dynamics observed after onsets and offsets of the back-ground contrast. Finally, we measure detection thresholds for tests presented on steadily flickering backgrounds as a function of the contrast of the background flicker. We show that the divisive feedback model for contrast gain control can describe these results as well.
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