Abstract
It has been shown that the rate of perceptual alternation between the left- and right-eye images during binocular rivalry is slowed by alcohol intake (Donnelly & Miller, 1995), indicating that alcohol enhances inhibitory mechanism that mediates visual competition. In previous studies, the acute alcohol effects on binocular rivalry have only been studied with simple geometric stimuli. These stimuli make it difficult to determine whether the alcohol influence on rivalry dynamics can occur at the object representation level. The purpose of this study is first to test the effect of alcohol on simple (two orthogonal 4cpd sinusoidal gratings) and complex stimuli ("face" and "house" images). In addition, the orthogonal sinusoidal gratings composed of either low (2 cpd) or high (6 cpd) spatial frequencies were used to investigate whether the inhibitory alcohol effect is spatial frequency specific. Young participants (N = 13, age 25±2.5 yrs) were tested in two randomized sessions, placebo and alcohol (0.8g/kg), and during each session they were tested twice, before the beverage and after the beverage consumption. The stimulus testing order was randomly interleaved. Participants reported rivalry percepts as a left-eye image, right-eye image or a piecemeal (mixed percept) by pressing pre-assigned buttons. The results showed that alcohol slowed alternation rate (approximately from 21 alternations to 15 alternations per minute) while alcohol’s reduction in alternation rate did not differ among stimulus types. Moreover, alcohol selectively increased the mean dominance time of piecemeal percepts from ~3.5 sec to ~5.5 sec after alcohol intake. However, the mean dominance time of the left or right eye image did not increase greatly (~0.4 sec increase) by alcohol. These results suggest that alcohol may interfere with the process for perceptual organization, leading to an increase in the likelihood of asynchronized local visual competition.
Meeting abstract presented at VSS 2013