Low confidence for perceptual completion of partially occluded objects

Pervasive gaps in sensory information are completed in perception. Interestingly, humans are unaware of that perceptual completion in cases of proximal gaps, which are caused by properties of their own sensory system, and report high confidence for the inferred information in those gaps. Here, we investigated whether such overconfidence is also observed in perceptual completion of visual information in distal gaps (i.e., those caused by the properties of the stimulus). In three experiments, we asked participants to perform a perceptual (type 1) task and report their confidence (type 2 task) using stimuli that were either intact (full stimulus), with a partial cutout (stimulus with gap), partially occluded (amodal completion) or induced (modal completion). We examined whether participants report high confidence for amodal and modal completion in comparison to a full stimulus or stimulus with gap. Over three experiments, participants had the highest confidence for full stimuli, whereas amodal and modal completion led to comparable confidence as stimuli with gap. These findings demonstrate that there was low confidence for stimuli whose distal gaps are perceptually filled in. In combination with previous research, our results suggest that visibility of the gaps in information influences confidence judgments.