Negligible fronto-parietal BOLD activity accompanying unreportable switches in bistable perception

The human ability to choose relies considerably on frontoparietal association cortex. Constructing unified perception from inconclusive sensory input also requires selection among alternatives. Combining fMRI with a novel visual stimulus, Brascamp and colleagues find evidence against frontoparietal involvement in such perceptual selection, instead suggesting choice capability in the visual system itself. The human brain's executive systems have a vital role in deciding and selecting among actions. Selection among alternatives also occurs in the perceptual domain; for instance, when perception switches between interpretations during perceptual bistability. Whether executive systems also underlie this functionality remains debated, with known fronto-parietal concomitants of perceptual switches being variously interpreted as reflecting the switches' cause or as reflecting their consequences. We developed a procedure in which the two eyes receive different inputs and perception demonstrably switches between these inputs, yet the switches themselves are so inconspicuous as to become unreportable, minimizing their executive consequences. Fronto-parietal fMRI BOLD responses that accompanied perceptual switches were similarly minimized in this procedure, indicating that these reflect the switches' consequences rather than their cause. We conclude that perceptual switches do not always rely on executive brain areas and that processes responsible for selection among alternatives may operate outside the brain's executive systems.