Not physically present contours can yield illusory motion.
We demonstrate a perceptual effect whereby contours not physically present in a visual scene can yield striking illusory motion. The not physically present contours are paths of invariant contrast polarity (CP). For example, when a square checkerboard composed of dark and light square checks with small black and white discs covering the vertices is put in lateral motion, there is the striking perception of vertical expansion/contraction. Such a checkerboard has (not physically present) diagonal paths of CP presentation with vertical components. However, when a square checkerboard made up of square black and very light checks with gray discs of luminance intermediate to the checks is put in lateral motion, no expansion/contraction is seen. For this checkerboard the vertical components of paths of CP preservation cancel each other out, predicting the lack of perception of vertical expansion/contraction. We also discuss how not physically present contours can explain previously described effects and suggest new effects to be explored.
Rutgers New Jersey Medical School, University Hospital, B-403, 150 Bergen Street, Newark, NJ 07103, USA. altschel@njms.rutgers.edu
Eric L
EL
Altschuler
Rutgers New Jersey Medical School, University Hospital, B-403, 150 Bergen Street, Newark, NJ 07103, USA.
Hee J
HJ
Kim
Rutgers New Jersey Medical School, University Hospital, B-403, 150 Bergen Street, Newark, NJ 07103, USA.
Abigail E
AE
Huang
Rutgers New Jersey Medical School, University Hospital, B-403, 150 Bergen Street, Newark, NJ 07103, USA.
Alice J
AJ
Hon
Rutgers New Jersey Medical School, University Hospital, B-403, 150 Bergen Street, Newark, NJ 07103, USA.
Meghan C
MC
McCormick
Dipartimento di Psicologia Generale, Università degli Studi di Padova, Room 310, via Venezia 8, 35131 Padova, Italy.
Sergio
S
Roncato
D015350:Contrast Sensitivity; D005556:Form Perception; D006801:Humans; D009039:Motion Perception; D009903:Optical Illusions / Q000502:physiology*; D010364:Pattern Recognition, Visual