Abstract
Some aspects of decision-making are known to decline with normal aging. To understand how age affects visual decision-making, we investigated age-related changes in perception during binocular rivalry (BR). In BR, the image presented to one eye competes with that presented to the other eye in order to achieve perceptual dominance. Perception during BR consists of alternations between exclusive percepts, however sometimes mixed percepts become more prevalent. In the first experiment, 52 observers, ranging from 17 to 72 years old, viewed rivalry stimuli and they were forced to make a choice between exclusive percepts. Stimuli were presented intermittently for 1 second, with a range of inter-stimulus intervals (0.125 – 2 seconds). The results show that perceptual alternations decrease at an older age. In the second experiment, we instructed 23 subjects divided into two age groups (21.5±3 and 59.3±6.4 years old) to report both exclusive and mixed percepts during the intermittent stimulus representation for the same setting as in experiment 1. In addition to a decline in perceptual alternation rate for the older group, the proportion of mixed percept also decreased for this group. Furthermore, the results show that during sustained exposure to BR stimuli, the proportion of mixed percepts among young and old subjects is not significantly different. These results challenge the hypothesis that older age differences in perceptual decision-making in BR are related to less adaptation and/or less cross-inhibition. To investigate the cause of this aging difference, we used the spiking neural model for BR by Laing and Chow (J. Comp. Neurosci., 2002). Our data and model suggest that differences in gain modulation at the input can simulate the aging aspect of perceptual decisions in BR, and not differences in parameters related to adaptation or synaptic depression.
Meeting abstract presented at VSS 2016