Abstract
The range of variation in environmental stimuli is much larger than the visual system can represent. It makes sense for the system to adjust its responses to the input statistics of the environment such as when our pupils contract to limit the light entering the eye, which comes at a cost to the representation of lower luminance levels. Previous evidence indicates that the visual system increasingly centers responses on the mean of the visual input and scales responses to its variation during adaptation. Here we tested to what degree adaptation to a brightness-varying stimulus will result in such adjustment of responses. The first two experiments tested whether the sensitivity to change in the amplitude and the mean of a large (9.6 deg) patch which varied sinusoidally in brightness over time (0.6Hz) would increase or decrease. In the third and fourth experiments this was tested for a dynamic peripheral stimulus (random patches moving around a circle on the screen) to test to what extent the effects uncovered in experiments 1 and 2 were driven by retinotopic mechanisms. Sensitivity to changes in mean and amplitude of the temporal brightness variation increased sharply the longer the adaptation to the variation both for the large patch as well as during variation of the random patches. The results show that adaptation to brightness variation leads to increased sensitivity to temporal brightness variation for both central and peripheral presentation.
Meeting abstract presented at VSS 2012