A Role for Control in an Action-Specific Effect on Perception

According to the action-specific account of perception, people perceive the spatial layout of the environment in relation to their ability to act. Pioneering research by Bhalla and Proffitt (1999) demonstrated that hills were judged as steeper to perceivers with less physiological potential. Since this seminal work, much research has shown these action-specific effects generalize beyond hill slant perception and beyond physiological potential, but the underlying mechanisms are underspecified. The present experiments explore the potential mechanism that information about action is integrated with visual information about the target. According to an integration account, information from various sources are weighted, and the strength of these weights dictates the strength of that source of information on the resulting percept. One prediction is that it should be possible to vary the strength of the weights and thereby vary the size of a particular effect. To reduce the effect of action on perception, control over the action was taken away from participants. As predicted, losing control reduced the impact of action on spatial perception. This is the first reported instance of a partial action-specific effect, and is consistent with an integration-based mechanism.