Abstract
The human visual system continuously adjusts its responses to optimize neural processing in a changing environment, a process known as visual adaptation. Although adaptation has been widely studied, it remains relatively unknown whether its dynamics change as familiarity with the adapting conditions increases. To test this question we introduced subjects into a novel visual environment, and measured adaptation on three consecutive days. Subjects viewed their surroundings through a head-mounted display (HMD), which presented them with filtered video from a camera attached to the HMD. The video was filtered to remove 99% of vertical energy, creating adapting conditions with previously unencountered visual statistics. Adaptation to such vertically deprived input has previously been shown to cause a tilt aftereffect (TAE) consistent with increased sensitivity of vertically-tuned neurons. During each day of the experiment, 7 subjects experienced two hours of vertical deprivation while watching popular films on an external monitor. TAE magnitude was assessed before deprivation, and after 30 minutes and 2 hours of adaptation. During these tests, subjects viewed brief presentations of a plaid stimulus, and used a keyboard to adjust the tilt of the two ~45 deg component gratings until the plaid appeared to contain square checks. Over the 3 days, the TAE grew larger at the 30 min timepoint, by 0.4 deg, but decreased at the 2 hour timepoint by 0.5 deg (statistical interaction between the two, p <0.04; overall average TAE was about 1.4 deg). Hence, as subjects became more familiar with the filtered visual statistics, the peak level of aftereffect caused by adaptation decreased, while the rate of growth of adaptation toward the peak increased. These results suggest that prior experience may allow the visual system to adapt faster to familiar environments and to limit aftereffects of this adaptation.
Meeting abstract presented at VSS 2014