Distinct mechanisms control contrast adaptation over different timescales

Min Bao, Elizabeth Fast, Juraj Mesik, Stephen Engel

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

Changes to the visual environment can happen at many timescales, from very transient to semi-permanent. To adapt optimally, the visual system also adjusts at different timescales, with longer-lasting environmental changes producing longer-lasting effects, but how the visual system adapts in this way remains unknown. Here, we show that contrast adaptation-the most-studied form of visual adaptation-hasmultiple controllers, each operating overa different time scale. In a series of experiments, subjects completed either a contrast matching, contrast detection, or tilt adjustment task, while adapting to contrast at one orientation. Following a relatively longer period (5 min) of adaptation to high contrast, subjectswere "deadapted"for a shorter period (e.g., 40 s) to a lower contrast. Deadaptation eliminated perceptual aftereffects of adaptation, but continued testing in a neutral environment revealed their striking recovery. These results suggest the following account: Adaptation was controlled by at least twomechanisms, with initial adaptation affecting a longertermone and deadaptation affecting a shorter-termone in the opposite direction. Immediately following deadaptation, the effects of the twomechanisms cancelled each other, but the short-term effects rapidly decayed, revealing ongoing longer-term adaptation. A single controlling mechanism cannot account for the observed recovery of effects, since once deadaptation cancels the initial longer-term adaptation, no trace of it remains. Combined with previous results at very long adaptation durations, the present results suggest that contrast adaptation is possibly controlled by a continuum of mechanisms acting over a large range of timescales.

Original languageEnglish (US)
Article number14
JournalJournal of vision
Volume13
Issue number10
DOIs
StatePublished - 2013

Keywords

  • Adaptation
  • Contrast
  • Spontaneous recovery
  • Timescale

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