title: The influence of exploration mode, orientation, and configuration on the haptic Müller-Lyer illusion.
abstract: We studied the impact of manner of exploration, orientation, spatial position, and configuration on the haptic Müller-Lyer illusion. Blindfolded sighted subjects felt raised-line Müller-Lyer and control stimuli. The stimuli were felt by tracing with the index finger, free exploration, grasping with the index finger and thumb, or by measuring with the use of any two or more fingers. For haptic judgments of extent a sliding tangible ruler was used. The illusion was present in all exploration conditions, with overestimation of the wings-out compared to wings-in stimuli. Tracing with the index finger reduced the magnitude of the illusion. However, tracing and grasping induced an overall underestimation of size. The illusion was greatly attenuated when stimuli were felt with the index fingers of both hands. Illusory misperception was not altered by the position in space of the Müller-Lyer stimuli. No effects of changes in the thickness of the line shaft were found, but there were effects of the length of the wing endings for the smaller, 5.1 cm stimuli. The theoretical and practical implications of the results are discussed.
authors.affiliation: Department of Psychology, Physical Sciences Building, Eastern Illinois University, 600 Lincoln Avenue, Charleston, IL 61920, USA. cfmah1@ux1.cts.eiu.edu
authors.forename: Morton A
authors.initials: MA
authors.lastname: Heller
authors.forename: Melissa
authors.initials: M
authors.lastname: McCarthy
authors.forename: Jennifer
authors.initials: J
authors.lastname: Schultz
authors.forename: Jayme
authors.initials: J
authors.lastname: Greene
authors.forename: Melissa
authors.initials: M
authors.lastname: Shanley
authors.forename: Ashley
authors.initials: A
authors.lastname: Clark
authors.forename: Samantha
authors.initials: S
authors.lastname: Skoczylas
authors.forename: Jamie
authors.initials: J
authors.lastname: Prociuk
mesh_terms: D000704:Analysis of Variance; D005260:Female; D005385:Fingers; D006225:Hand; D006801:Humans; D007088:Illusions; D007600:Judgment; D008297:Male; D009068:Movement; D009903:Optical Illusions; D009949:Orientation; D010812:Physical Stimulation / Q000379:methods; D011581:Psychological Tests; D013933:Thumb; D014110:Touch