Abstract
Vision adapts to different environments. For example, when wearing colored glasses, the world gradually appears less tinted. For repeatedly encountered environments, the visual system may learn to adapt almost instantly to maintain accurate perception. We previously reported that wearing red glasses for 5 one-hour periods a day, separated by 1 hr gaps, over 5 days, caused the world to appear less and less reddish when first putting on the glasses (Li et al., eLife, 2020). However, the factors that control this learning remain unknown. Here, we tested if observers can learn to adapt more rapidly when environmental change is less frequent. Ten observers wore red glasses for a single 5-hr period on 5 consecutive days. We measured adaptation by asking them to adjust the color of a 0.5-degree square, presented on a naturalistic background, to “unique yellow”, containing neither red nor green. Observers performed five-min blocks of this task, beginning with the glasses off. Then, they put on the glasses and immediately performed another block, and then again every 10 mins for 1 hr. Observers next went about their daily activities with the glasses on for 3 hrs. During the fifth hour of wear, they repeated identical task blocks as during the first hour. When observers first put on the glasses, the world appeared very reddish, so their unique yellow settings were physically very greenish. As vision adapted during the 5 hr of wear, the redness faded, and observers’ settings became less greenish. Critically, across days, the first unique yellow setting with glasses on became significantly less and less greenish (p < 0.001), indicating stronger immediate adaptation. The preceding glasses-off blocks showed no change in settings. This pattern suggests that the single daily experience of the novel environment was sufficient to teach the visual system to adapt more rapidly.