Decrement of Visual and Haptic Müller-lyer Illusion on Repeated Trials: A Study of Crossmodal Transfer

Abstract

Twenty adults, 10 male and 10 female, ranging in age from 22 to 54 years, were asked to set the centre arrowhead of a Müller-Lyer pattern for 80 consecutive trials. Ten of the subjects did so visually, while 10 blindfolded subjects made the settings haptically, i.e. by active palpation. Following the 80th trial, those subjects who had been making settings visually were blindfolded and were asked to make six haptic settings. Conversely, those who had made 80 haptic settings proceeded to make six settings visually. The initial size of the illusion was essentially identical for the visual and haptic groups. Both groups showed significant decrement, since 19 of the 20 subjects had a smaller illusion on trials 71–80 than on trials 1–10. There was significant transfer of the decrement to the six settings made in the other modality. However, transfer effects were greater for the subjects who went from touch to vision than for those who went from vision to touch. Verbalization did not appear to be the vehicle of these crossmodal transfer effects.