Abstract
Binocular rivalry is a form of visual ambiguity that occurs when dissimilar images are presented to each of the two eyes. Despite unchanging visual stimulation, perception fluctuates between two possible interpretations of the input, suggesting that the mechanisms underlying binocular rivalry may ultimately give rise to our visual awareness. Recent studies have established that attention can modulate rivalry dynamics, indicating some degree of internal control. Here, we examined whether prolonged practice at directing endogenous attention toward one of the two eyes can lead to lasting changes in low-level visual mechanisms.
In our training experiment (twelve 30-minute sessions), subjects viewed a flickering bullseye stimulus presented to one eye (trained eye), and a rotating pinwheel stimulus presented to the other (untrained) eye. Whenever the bullseye was dominant, subjects were instructed to identify slight changes in its aspect ratio. This attentionally demanding task increased dominance durations of the attended stimulus, with the magnitude of this effect increasing over the course of training. Additionally, training shortened dominance durations of the unattended stimulus, ultimately resulting in strong predominance of the attended stimulus.
A battery of pre- and post-training tests, including tests with stimuli not used during training, indicated that the training induced effects were strongly eye-specific. Importantly, these changes in rivalry dynamics were observed even when attention was not directed toward one of the rival stimuli, demonstrating broad plasticity that also extended to untrained stimuli. These novel results indicate that prolonged directed attention during rivalry can lead to low-level changes in the visual system.