Side-by-Side Observation of the <i>Ebbinghaus illusion</i> Affects Motor Performance, But Not Learning

Abstract

Background: The Ebbinghaus illusion may influence performers’ perceptions during the immediate execution of aiming tasks. However, it remains unclear whether these effects lead to relatively permanent changes in skill acquisition. Existing evidence is conflicting, and the role of self-efficacy under visual illusion conditions requires further investigation. Objectives: This study aimed to investigate the effect of the Ebbinghaus illusion on learning a golf-putting task. Methods: The small-perception group (SPG), large-perception group (LPG), and control group (CG) practiced a 2-m golf-putting task. During practice, the SPG and LPG observed small and large illusory circles around the hole, respectively, whereas the CG practiced without visual illusions. Learning was assessed by performance on a retention test conducted 24 hours later without illusions. Results: The perceived size of the hole was influenced by the surrounding circles, and self-efficacy was higher in the LPG. The effects on perception and self-efficacy were also sustained at retention. In addition, putting accuracy during practice was greater in the LPG. However, no significant between-group differences in learning were observed. Conclusions: Although practice with visual illusions influenced performance, the results did not replicate previous findings regarding learning, as assessed by retention performance. Further research is needed to clarify the mechanisms underlying perception-action coupling, particularly with respect to enhanced expectancies induced by visual illusions.