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The Haptic Muller-Lyer Illusion In Sighted And Blind People, Morton A. Heller, Deneen D. Brackett, Kathy Wilson, Keiko Yoneyama, Amanda Boyer, Heather Steffen

Morton A. Heller

We examined the effect of visual experience on the haptic Mu« ller-Lyer illusion. Subjects made size estimates of raised lines by using a sliding haptic ruler. Independent groups of blind- folded-sighted, late-blind, congenitally blind, and low-vision subjects judged the sizes of wings-in and wings-out stimuli, plain lines, and lines with short vertical ends. An illusion was found, since the wings-in stimuli were judged as shorter than the wings-out patterns and all of the other stimuli. Subjects generally underestimated the lengths of lines. In a second experiment we found a nonsignificant difference between length judgments of raised lines as opposed to …