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

The human brain's executive systems play 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 paradigm where the two eyes receive different inputs and perception demonstrably switches between these inputs, yet where switches themselves are so inconspicuous as to become unreportable, minimizing their executive consequences. Fronto-parietal fMRI BOLD responses that accompany perceptual switches were similarly minimized in this paradigm, 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 of the brain's executive systems.