A further step in Pylyshyn's discontinuity thesis is to examine the penetrability of haptic (tactual-kinesthetic) perception. The study of the perception of orientation and the “oblique effect” (lower performance in oblique orientations than in vertical–horizontal orientations) in the visual and haptic modalities allows this question to be discussed. We suggest that part of the visual process generating the visual oblique effect is cognitively impenetrable, whereas all haptic processes generating the haptic oblique effect are cognitively penetrable.

Constructivist and ecological approaches are also observed in tactile perception studies. The question is whether identification and localization are dissociated in the tactile modality as well, and whether Norman's conception may be generalized to the field of touch. An analogue to blindsight was evidenced in passive touch, but no such dissociation was observed in active touch. A study is in progress in this domain.

We discuss the assumptions put forward by Thelen et al. about motor planning processes. We examine the results of an experiment inspired by the authors' contention that the motor plans of both infants and adults are continuous and graded. We wondered whether adults, in an adapted version of the A-not-B error paradigm, would point between the A and B targets, as in some degraded conditions of pointing (Ghez et al. 1990), or would make A-not-B errors. Unexpectedly, we observed that adults (...) tended to shift the direction of their pointings to B away from A, and did not make any A-not-B errors. (shrink)