Influence of shape of receptor organ on the horizontal-vertical illusion in passive touch.

Abstract

In four experiments involving 156 5s, stimulus templates were traced onto the volar surface of 5's forearm. Experiment I showed that rotation of a T figure over 180° resulted in an illusion function, with a reversal of the effect at 90°. A similar function was obtained in Experiment II with an L figure, indicating the absence of a bisection effect. The component line along the shorter lateral axis was judged longer than that aligned with the longitudinal axis of the forearm. Experiments III and IV indicated that the effect was independent of the degree of stimulation on the skin and that an inscribed circle was similarly affected and perceived as a lateral ellipse. It was concluded that the horizontal-vertical illusion in passive touch is a function of the orientation of the figure with reference to the elongated frame of the receptor organ and is independent of the effect in vision and active touch.

Tactile spatial sensitivity and anisotropy

“…Previous studies (Essock et al, 1992(Essock et al, , 1997Geldard & Sherrick, 1983;B. G. Green, 1982;Lechelt, 1988Lechelt, , 1992Vierordt, 1870;Weber, 1834Weber, /1996Wheat & Goodwin, 2000;Wong et al, 1974), as well as the results from Experiments 2 and 3, support this view. One could imagine, however, that other dimensions of tactile sensitivity, such as intensive or temporal dimensions, might also show anisotropy.…”

“…Several recent studies (Essock, Krebs, & Prather, 1992Fuchs & Brown, 1984;Geldard & Sherrick, 1983;B. G. Green, 1982;Lechelt, 1988Lechelt, , 1992Stevens & Patterson, 1995;Wheat & Goodwin, 2000;Wong, Ho, & Ho, 1974) have noted changes in sensitivity as a function of the orientation of the stimuli on the body; however, the only previous systematic studies (Vierordt, 1870;Weber, 1834Weber, /1996 of anisotropy, which included multiple test sites, have used the two-point threshold, a problematic measure of spatial sensitivity.…”

The influence of vision, touch, and proprioception on body representation of the lower limbs

“…For instance, Cholewiak (1999) showed no effect of direction when making judgments about two unseen tactile stimuli applied to the thigh (as we show here), whereas Green (1982) showed that participants significantly underestimated distances applied to the thigh in the longitudinal direction compared to the transverse direction. Similar findings have been replicated for estimates made about the hand (Longo & Haggard, 2011) and arms (Le Cornu-Knight et al, 2014;Green, 1982;Wong, Ho, & Ho, 1974) as well. With respect to the shin, investigations on tactile distance perception for the lower leg are lacking in the literature.…”

Anisotropic distortion in the perceived orientation of stimuli on the arm

“…There have been a number of reports on discrepancies between tactile space and physical space 1 – 3 , 6 – 11 , 14 , 15 . For example, touch distances along the arm were perceived to be longer than those across the arm 3 , 7 , and touch locations on the arm were perceived to be closer to the wrist and the elbow 2 , 10 . Some studies investigated localization for touch and even pain on the dorsal surface of the hand and arm, and found that stimulus localization was more accurate (smaller uncertainty intervals) in the short axis than in the long axis 10 , 11 .…”