abstract: Previous research has shown that perceptual illusions can enhance golf putting performance, and the effect has been explained as being due to enhanced expectancies. The present study was designed to further understand this effect by measuring putting in 3 additional variations to the Ebbinghaus illusion and by measuring putting kinematics. Nineteen ASU students with minimal golf experience putted to the following illusion conditions: a target, a target surrounded by small circles, a target surrounded by large circles, a target surrounded by both large and small circles, no target surrounded by small circles and no target surrounded by large circles. Neither perceived target size nor putting error was significantly affected by the illusion conditions. Time to peak speed was found to be significantly greater for the two conditions with no target, and lowest for the condition with the target by itself. Suggestions for future research include having split groups with and without perceived performance feedback as well as general performance feedback. The size conditions utilized within this study should continue to be explored as more consistent data could be collected within groups. / Dissertation/Thesis / Masters Thesis Human Systems Engineering 2019

Page 193 is included twice. Numbered the same, but are different pages. / Although visual illusions have been used extensively to explore the mechanisms subserving perception and action, controversy exists regarding the extent to which illusions may differentially affect the perceptual and motor systems. In part, this is because it is often difficult to accurately assess the perceptual influence of illusory stimuli since participants are usually asked only to report binary size decisions (bigger or smaller) of an illusory stimulus relative to a control figure. Questions of relative size or the direction of misperception remain unanswered. In this thesis, 10 experiments, comprising eight separate studies, were conducted to address these issues. In Experiment 1, a software tool was developed that allowed participants to size-match a target to a Control figure (Experiment 1a), as well as both the Large (Experiment 1b) and Small Annuli (Experiment 1c) Ebbinghaus Illusion stimuli. These experiments provided an accurate percentage of misperception score when each of the three conditions was presented in isolation. Results from Experiment 2, however, suggest that when each of the three conditions are presented in a random and repeated stimulus array, a degree of perceptual adaptation occurs in which illusory effects are biased in the direction of the large annuli stimulus. Experiments 3-8 provided evidence to suggest that the degree of motor involvement (Experiment 3), number of illusory stimuli present (Experiments 4 and 5), direction of attention (Experiment 6) and visual field laterality (Experiments 7 and 8) have minimal influence on the adaptation effects observed in Experiment 2. / Thesis / Master of Science (MSc)