Spatial navigation within a real 3-D maze was investigated to study space perception on the sole basis of tactile information transmitted by means of a 'tactile vision substitution system' (TVSS) allowing the conversion of optical images-collected by a micro camera-into 'tactile images' via a matrix in contact with the skin. The development of such a device is based on concepts of cerebral and functional plasticity, enabling subjective reproduction of visual images from tactile data processing. Blindfolded sighted subjects had to remotely control the movements of a robot on which the TVSS camera was mounted. Once familiarised with the cues in the maze, the subjects were given two exploration sessions. Performance was analysed according to an objective point of view (exploration time, discrimination capacity), as well as a subjective one (speech). The task was successfully carried out from the very first session. As the subjects took a different path during each navigation, a gradual improvement in performance (discrimination and exploration time) was noted, generating a phenomenon of learning. Moreover, subjective analysis revealed an evolution of the spatialisation process towards distal attribution. Finally, some emotional expressions seemed to reflect the genesis of 'qualia' (emotional qualities of stimulation).

A methodological approach to perceptual learning was used to allow both early blind subjects (experimental group) and blindfolded sighted subjects (control group) to experience optical information and spatial phenomena, on the basis of visuo-tactile information transmitted by a 64-taxel pneumatic sensory substitution device. The learning process allowed the subjects to develop abilities in spatial localisation, shape recognition (with generalisation to different points of view), and monocular depth cue interpretation. During the training phase, early blind people initially experienced more difficulties than blindfolded sighted subjects (having previous perceptual experience of perspective) with interpreting and using monocular depth cues. The amelioration of the performance for all blind subjects during training sessions and the quite similar level of performance reached by two groups in the final navigation tasks suggested that early blind people were able to develop and apply cognitive understanding of depth cues. Both groups showed generalisation of the learning from the initial phases to cue identification in the maze, and subjectively experienced shapes facing them. Subjects' performance depended not only on their perceptual experience but also on their previous spatial competencies.

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This article analyzes the attraction of stimulation produced by a visuo tactile sensory substitution device, which was designed to provide optical infor mation to infants who are blind via a tactile modality. The device was fi rst tested on sighted infants, to demonstrate that this type of stimulation on the abdomen is pleasant and rewarding in comparison to visual and auditory reinforcement. The preliminary results of this research allow us to consider the possibility of devel oping practical visual-substitution devices for infants who are blind.

We investigated handedness in relation with haptic perception and not with motor ability. Habituation and novelty reaction procedure in haptic modality was used to provide evidence for indices of laterality, as early as 2 months of life. After a tactual habituation with either the left hand (lh) or right hand (rh), infants received an intramodal discrimination test performed in the same hand as the habituation, or a transfer test performed in the opposite hand. A third group received a tactual habituation with both hands. Three main results were obtained : 1 / in 2-month-old infants, habituation was observed in the Left as well as in the Right Hand ; 2 /perceptual performance differed according to the hand. Holding time was longer during the first three trials in the rh than in the lh. However, total holding time and number of trials for habituation were greater during left handling. These results provide evidence of two indications of laterality in the course of haptic habituation process : the object holding (rh > lh) and the information processing (lh > rh) ; 3 / results obtained on information transfer from one hand to the other were ambiguous. RésuméCette étude examine le problème de la latéralité manuelle en relation avec les capacités perceptives du bébé et non son habileté motrice. La procédure d'habituation et de réaction à la nouveauté dans la modalité tactile est utilisée afin de mettre en évidence un indice de latéralité dès 2 mois. Après habituation sur la main gauche (mg) ou sur la main droite (md), les enfants reçoivent un test de discrimination intramodale effectué de la même main ou de la main opposée. Un troisième groupe reçoit une habituation tactile des deux mains. Trois résultats principaux sont obtenus : 1 / à 2 mois, l'habituation est observée de la mg comme de la md ; 2/ les performances perceptives diffèrent suivant la main. Le maintien de l'objet est plus long dans la md que dans la mg aux trois premiers essais. Cependant, le temps total d'exploration et le nombre d'essais nécessaires à l'habituation sont plus importants lors d'une manipulation mg. Ces résultats mettent en évidence deux indices de latéralité au cours du processus d'habituation tactile : la manipulation ponctuelle d'un objet (md > mg) et le traitement d'information (mg > md) ; 3 / Les résultats obtenus sur le transfert d'information d'une main à l'autre sont moins clairs.