Distal bias in knuckle mislocalisation is reduced but not eliminated by hand inspection

Knowledge of knuckle location shows highly stereotyped distortions: people judge their knuckles as farther forward in the hand than they actually are. This distal bias does not rely on any specific stimulus cue or single sensory modality, but rather reflects a conceptual misrepresentation of hand structure (Ambroziak, in press; Longo, 2015). Here, in 2 experiments, we investigated whether distal bias can be eliminated by careful inspection of participant’s own hand in movement. In Experiment 1, participants performed a knuckle localization task both before and after being allowed to explore the actual configuration of their hand. During the task, participants judged the location of their knuckles by pointing to the location on the palm directly opposite their knuckle. During the intervention, participants were inspecting their hand while bending their fingers. In Experiment 2, participants performed the same task three times: before any intervention, after inspecting the hand while splaying the fingers and after inspecting the hand while bending the fingers. In both experiments, after the interventions participants judged their knuckles to be closer to the actual location, however, significant distal bias still remained. These results showed that distal bias can be reduced but not eliminated by inspection of participant’s own hand.