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Sensory substitution constitutes an interesting domain of study to consider the philosopher's classical question of distal attribution: how we can distinguish between a sensation and the perception of an object that causes this sensation. We tested the hypothesis that distal attribution consists of three distinct components: an object, a perceptual space, and a coupling between subjects' movements and stimulation. We equipped sixty participants with a visual-to-auditory substitution device, without any information about it. The device converts the video stream produced by a head-mounted camera into a sound stream. We investigated several experimental conditions: the existence or not of a correlation between movements and resulting stimulation, the direct or indirect manipulation of an object, and the presence of a background environment. Participants were asked to describe their impressions by rating their experiences in terms of seven possible "scenarios". These scenarios were carefully chosen to distinguish the degree to which the participants attributed their sensations to a distal cause. Participants rated the scenarios both before and after they were given the possibility to interrupt the stimulation with an obstacle. We were interested in several questions. Did participants extract laws of co-variation between their movements and resulting stimulation? Did they deduce the existence of a perceptual space originating from this coupling? Did they individuate objects that caused the sensations? Whatever the experimental conditions, participants were able to establish that there was a link between their movements and the resulting auditory stimulation. Detection of the existence of a coupling was more frequent than the inferences of distal space and object.

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Work aimed at studying social cognition in an interactionist perspective often encounters substantial theoretical and methodological difficulties: identifying the significant behavioral variables; recording them without disturbing the interaction; and distinguishing between: (a) the necessary and sufficient contributions of each individual partner for a collective dynamics to emerge; (b) features which derive from this collective dynamics and escape from the control of the individual partners; and (c) the phenomena arising from this collective dynamics which are subsequently appropriated and used by the partners. We propose a minimalist experimental paradigm as a basis for this conceptual discussion: by reducing the sensory inputs to a strict minimum, we force a spatial and temporal deployment of the perceptual activities, which makes it possible to obtain a complete recording and control of the dynamics of interaction. After presenting the principles of this minimalist approach to perception, we describe a series of experiments on two major questions in social cognition: recognizing the presence of another intentional subject; and phenomena of imitation. In both cases, we propose explanatory schema which render an interactionist approach to social cognition clear and explicit. Starting from our earlier work on perceptual crossing we present a new experiment on the mechanisms of reciprocal recognition of the perceptual intentionality of the other subject: the emergent collective dynamics of the perceptual crossing can be appropriated by each subject. We then present an experimental study of opaque imitation (when the subjects cannot see what they themselves are doing). This study makes it possible to characterize what a properly interactionist approach to imitation might be. In conclusion, we draw on these results, to show how an interactionist approach can contribute to a fully social approach to social cognition.

A quarter of a century ago, in the preface to « Brain Mechanisms in Sensory Substitution », Paul Bach y Rita wrote: "This monograph thus risks becoming outdated in a very short time since the development of refined sensory substitution systems should allow many of the question raised here to be answered, and some of the conclusions may appear naive to future readers." (BACH Y RITA, 1972) As it turns out, this prediction is far from having been fulfilled: in spite of their scientific and social interest, their real effectiveness and a certain technological development, prosthetic devices employing the principle of "sensory substitution" are not widely used by the blind persons for whom they were originally destined. After a brief recall of the general principle of sensory substitution, we will advance several hypotheses to account for this situation. We will then identify some elements which may favour the conception and, especially, the usability of future devices. To this end, we will focus our analysis on the work of Bach-y-Rita, particularly well documented, devoted to TVSS (Tactile Vision Sensory Substitution) since the 1960's. This choice is motivated by the extensive and exemplary nature of this research, devoted to the rehabilitation of a handicapped population, as an enterprise which is both technical and scientific in character. We will also present the specific interest of substitution systems employing tactile stimulation, and we will emphasize the essential coordination of fundamental and technological research in this area. In addition, besides their direct utility for handicapped persons, these devices open broad experimental and theoretical perspectives on cognition in general (brain plasticity, perception,