Influence of visual illusion and attentional focusing instruction in motor performance. Issue 1 (2nd November 2019) - Marchant, David C.
Abstract : The present study examined the individual and combined influences of two factors that have been shown to benefit motor performance: an external focus of attention and the visual context of a target being aimed for. In a within-subjects design participants completed golf putts using control (C), internal (IN) and external (EX) attentional focus (AF) instructions under target-based visual illusion (perceptually larger (PLT) versus smaller (PST) targets) conditions. Twenty-six novice golfers completed six putts in each counterbalanced condition. Mean radial accuracy (cm) was calculated. Through the use of surrounding distracting visual stimulus, an Ebbinghaus illusion aimed to induce PLT or PST during putting. Verbal instruction directed attention to C (no specific focus), IN (arm movements) or EX (movement effect focus) focuses prior to execution. The Ebbinghaus illusions significantly altered perceived target size. Significant main effects indicated: (1) greater accuracy in EX (PLT: 27.32 vs. PST 31.46 cm) vs. IF (30.50 vs. 39.82 cm) and C (32.11 vs. 36.97 cm); (2) accuracy was benefited when putting towards the PLT vs. PST. No AF × Illusion interaction was evident. Performance was independently affected by AF and target visual context (e.g. perceived target size), suggesting different mechanisms in motor execution: instructions influence the control of movement whereas the target conditions inform motor planning through perceptual and motivational variables.