Illusory contour representation across modal and amodal completion

• Main Author: Chay, Man Ting
• Other Authors: Gerrit Maus
• Format: Final Year Project
• Language: English
• Published: 2019
• Subjects: DRNTU::Social sciences::Psychology
• Online Access: http://hdl.handle.net/10356/76877
• Institution: Nanyang Technological University

Our visual system perceptually fills in incomplete visual information. An example of perceptually completed stimuli are illusory contours, which are perceived edges without physical components. A previous study has demonstrated inhibited contour interpolation in the blind spot, and suggested the importance of V1 neurons in contour interpolation. However, it remains unclear whether this impairment can also be observed in other forms of interruption. Therefore, this study aims to investigate illusory contour representation in the blind spot (modal completion) and across an occluder (amodal completion). We adapted the dot localization paradigm which requires participants to estimate the illusory contour position by judging whether a briefly flashed dot appeared inside or outside of the illusory shape. Based on existing literature, we hypothesized that performance deficits would be observed in illusory contours passing through the blind spot, but not in partially occluded illusory contours. Surprisingly, results showed comparable illusory contour localization performance between illusory contours passing through the blind spot and uninterrupted illusory contours, suggesting that intact neural representation can possibly be formed based on feedback signals from higher-level visual areas and lateral interactions within V1. Additionally, performance deficits (i.e., more bias and less precise) in partially occluded illusory contours reflect that the formation of intact illusory contour representation is only interrupted by real occluding objects. Recommendations are given for future research to further explore contour interpolation in amodal completion and compare the performance differences with pathological retinal scotomas.