Influences of Selective Attention during Binocular Rivalry

Binocular rivalry is a unique perceptual phenomenon in which sensation and perception are dissociated. Despite the presentation of unchanging sensory stimulation (disparate images in each of the two eyes), an observer's perceptual experience fluctuates between the two equally plausible interpretations of the input. Perhaps surprisingly, one consistent finding is that this process is largely inaccessible to selective attentional control — in other words, observers cannot willfully cause greater predominance of one or the other image, except under certain special circumstances. Because this paradigm so starkly illustrates the limits of voluntary attention, it represents a unique opportunity for studying the factors that promote attentional control.

The series of studies comprising this thesis are designed to investigate ways of overcoming the limitations of attentional control during binocular rivalry. To begin, the complex pattern of results in the attention and rivalry literature are explained within the framework of the biased competition theory of attention, a theory that is found to synthesize seemingly diverse results from previous studies. This framework is then tested in a number of studies, with results supporting several predictions arising from this novel understanding. First, we find that direct practice at a demanding perceptual task during binocular rivalry can give rise to profound selective control. We next investigate whether this increase in attentional control of binocular rivalry might also be achieved through less direct training. Specifically, we compared attentional control of binocular rivalry in video game players and experienced psychophysical observers to control in non-gamers, and found some support for the idea that extensive visual training may be necessary for observers to attentionally control binocular rivalry. Finally, we tested how the effects of attention over binocular rivalry change throughout its timecourse and found that attentional control emerges near the end of each percept, as competition between stimuli becomes less resolved. Taken together, these experiments reveal ways of overcoming limitations in attentional control of visual perception, and demonstrate a key role of visual competition in the activity of attentional mechanisms.