Ebbinghaus visual illusion: no robust influence on novice golf-putting performance

Visual illusions influence proceduralized sports performance

Does the Ebbinghaus visual illusion really influence sports performances? Does the influence depend on the type of knowledge (procedural vs. declarative) that guides movement? To address these questions, we evaluated the knowledge hypothesis, a novel hypothesis according to which the more sports performance relies on procedural knowledge, the more it will be influenced by visual illusions. In the context of golf putting, we first used the high-error/low-error motor-learning technique (Experiment 1) or varied the number of practice trials (Experiment 2) to induce novice participants to rely more on procedural knowledge than on declarative knowledge (or vice versa). We then manipulated the perceived size of two golf holes by projecting a ring of small or large circles around them, which caused the holes to appear larger or smaller, respectively. This Ebbinghaus visual illusion had an influence on putting in both experiments. We also observed a pattern of findings consistent with the knowledge hypothesis: the procedural groups were moderately influenced by the illusion when putting, but the declarative groups were influenced only weakly, at best. Among the participants most sensitive to the illusion, the analyses confirmed a significantly stronger influence for the procedural group. Overall, these findings demonstrate that the effect of visual illusions on sports performance is a reliable phenomenon for proceduralized actions. The knowledge hypothesis represents an attractive way of reconciling earlier divergent findings.

The Effect of Large Visual Illusion and External Focus of Attention on Gaze Behavior and Learning of Dart Throw Skill

Research has shown that large visual illusions and an external focus of attention can improve novice’s motor learning. However, the combined effects of these approaches and the underlying mechanisms have yet to be studied. Therefore, the present study examined the effects of a large visual illusion and an external focus on the learning of a dart throwing task in novices and measured the perceptual mechanisms underpinning learning using quiet eye. Forty novice participants were randomly divided into four groups: large visual illusion, external focus of attention, combined large visual illusion and external focus of attention, and control group. The study consisted of a pretest, a practice phase, an immediate retention test, a 24-hr retention test, and a transfer test. Results revealed that all groups increased throwing accuracy and quiet eye duration from pretest to immediate retention. In the immediate retention, 24-hr retention, and transfer test, large visual illusion had greater accuracy and longer quiet eye duration than the control group. In addition, there were no significant differences between the visual illusion and external focus groups for throwing accuracy and quiet eye duration. The findings suggest that combining large visual illusion and external focus can independently improve motor learning but combining these manipulations does not have additive benefits.