E. Gentaz et al., The reproduction of vertical and oblique orientations in the visual, haptic, and somato-vestibular systems, Q J EXP P-A, 54(2), 2001, pp. 513-526
Citations number
37
Categorie Soggetti
Psycology
Journal title
QUARTERLY JOURNAL OF EXPERIMENTAL PSYCHOLOGY SECTION A-HUMAN EXPERIMENTAL PSYCHOLOGY
This study investigates whether the vertical orientation may be predominant
ly used as an amodal reference norm by the visual, haptic, and somato-vesti
bular perceptual systems to define oblique orientations. We examined this q
uestion by asking the same sighted adult subjects to reproduce, in the fron
tal (roll) plane, the vertical (0 degrees) and six oblique orientations in
three tasks involving different perceptual systems. In the visual task, the
subjects adjusted a moveable rod so that it reproduced the orientation of
a visual rod seen previously in a dark room. In the haptic task, the blindf
olded sighted subjects scanned an oriented rod with one hand and reproduced
its orientation, with the same hand, on a moveable response rod. In the so
mato-vestibular task, the blindfolded sighted subjects, sitting in a rotati
ng chair, adjusted this chair in order to reproduce the tested orientation
of their own body. The results showed that similar oblique effects (unsigne
d angular error difference between six oblique orientations and vertical or
ientation) were observed across the three tasks. However, there were no pos
itive correlations between the visual, haptic, and somato-vestibular obliqu
e effects. Moreover, in some oblique orientations, there was a tendency to
overestimate the angle between the oblique orientation and the vertical ori
entation. This effect varied according to the orientation value and the mod
ality. Taken together, these findings suggest that although vertical orient
ation is used as a reference norm in the visual, haptic, and somato-vestibu
lar systems to define oblique orientations, specific processing mechanisms
seem to be at work in each perceptual system.