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Cherlyn Ng, Bart Farell; Rapid adaptation in stereopsis. Journal of Vision 2017;17(10):1057. doi: 10.1167/17.10.1057.
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© ARVO (1962-2015); The Authors (2016-present)
Adaptation is a canonical computation that compares stimuli in the context of the temporal history and spatial surround. Adaptation maximizes neurons' dynamic range, stabilizes activity despite large environmental variations, is energetically efficient, improves discrimination thresholds and enables perceptual constancy. However, the consequences are aftereffects that shift percepts away from the adaptor and reduce sensitivity to the adapting stimulus. Classical experiments use these aftereffects to quantify adaptation with the adapting stimulus typically presented for tens of seconds. However, since saccadic latency can be in the order of milliseconds, humans should be able to adapt at much shorter timescales as well. There is physiological evidence for such rapid adaptation, and a report that it is perceptually apparent in auditory encoding. We ask here if stereopsis, which is thought to have sluggish dynamics, is susceptible to rapid adaptation. To that end, the adapting stimulus was presented for 500ms prior to a test stimulus that also lasted the same duration. Both adaptor and test stimuli were full-field dynamic random dot stereograms that could either be nearer or farther than the fixation cross. We investigated the effect of depth polarity and magnitude of the adaptors on stereo-thresholds and biases. 3/3 subjects demonstrated higher thresholds when the adaptors were of the same depth polarity as the test. Adaptors with large disparities were more effective in reducing performance than small-disparity adaptors. Consistent with the presence of aftereffects, adaptors that were nearer than the fixation biased responses towards positive disparities and vice versa. Accommodation and vergence movements during adaptation cannot explain these results because performance would be reversed if that were the case. Hence, we conclude that stereopsis can adapt to brief stimuli presentations and is well poised for rapid changes to local visual stimulation.
Meeting abstract presented at VSS 2017
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