Confidence as a diagnostic tool for perceptual aftereffects

Perceptual judgements are, by nature, a product of both sensation and the cognitive processes responsible for interpreting and reporting subjective experiences. Changed perceptual judgements may thus result from changes in how the world appears (perception), or subsequent interpretation (cognition). This ambiguity has led to persistent debates about how to interpret changes in decision-making, and if cognition can change how the world looks, or sounds, or feels. Here we introduce an approach that can help resolve these ambiguities. In three motion-direction experiments, we measured perceptual judgements and subjective confidence. Sensory encoding changes (i.e. the motion-direction aftereffect) impacted each measure equally, as the perceptual evidence informing both responses had changed. However, decision changes dissociated from reports of subjective uncertainty when non-perceptual effects changed decision-making. Our findings show that subjective confidence can provide important information about the cause of aftereffects, and can help inform us about the organisation of the mind.