Although motor learning can occur from observing others perform a motor skill (action observation; AO), observers’ confidence in their own ability to perform the skill can be falsely increased compared to their actual ability. This illusion of motor competence (i.e., ‘over-confidence’) may arise because the learner does not gain access to sensory feedback about their own performance—a source of information that can help individuals understand their veridical motor capabilities. Unlike AO, motor imagery (MI; the mental rehearsal of a motor skill) is thought to be linked to an understanding of movement consequences and kinaesthetic information. MI may thus provide the learner with movement-related diagnostic information, leading to greater accuracy in assessing ability. The present study was designed to evaluate the effects of MI when paired with AO in assessments of one’s own motor capabilities in an online observation task. Two groups rated their confidence in performing a juggling task following repeated observations of the action without MI (OBS group; n = 45) or with MI following observation (OBS+MI; n = 39). As predicted, confidence increased with repeated observation for both groups, yet increased to a greater extent in the OBS relative to the OBS+MI group. The addition of MI appeared to reduce confidence that resulted from repeated AO alone. Data support the hypothesis that AO and MI are separable and that MI allows better access to sensory information than AO. However, further research is required to assess changes in confidence that result from MI alone and motor execution.
