In daily life, an action we select at once is often a "habituated" one we have iteratively performed. Do we choose those actions because we like them or find them easy? A psychological phenomenon that may answer this question is the "mere exposure effect (MEE)", by which repeated exposure of a stimulus object to an individual enhances his/her attraction to the object. However, it remains unclear whether a phenomenon of MEE occurs in the case of repetitive visuomotor associations. In the present study, we aimed at clarifying the effects of repeatedly executed or observed actions onto preference evaluation for visually presented stimuli indicating actions (visuomotor MEE).
Sixteen healthy subjects first participated in a pre-rating session with a set of visual stimuli showing hand-signs (finger alphabets). The participants rated those stimulus using visual analogue scaling for evaluate a preference rating (PR) based on a like-dislike scale and also an easiness rating (ER) based on an easy-difficult scale. Next, they were repeatedly presented with the hand-sign stimuli, and instructed to imitate or merely observe them (exposure session). After exposure to the same stimulus for 5 times in each condition, the participants underwent a midterm-rating session for PR and ER of all of the stimuli. Following the midterm-rating session, the exposure session was resumed. Thus, they were exposed to a set of hand-sign stimulus for 10 times in each condition. Finally, the participants underwent a post-rating session for PR and ER. As control stimuli, we prepared a set of hand-sign stimuli used only for PR and ER (no exposure).
The behavioral data showed that increases in PR for the imitated stimuli were significantly larger than those for the observed stimuli (p<.05) and larger than those for control stimuli with marginal significance (p<.10) . However, the difference in ER between the pre and post-rating sessions was not significantly affected by the exposure. These results suggest that repeated motor imitations elicit greater MEE than do repeated motor observations for visual stimuli associated previously with actions.