Recalibración perceptiva y epistemológica prostética

• Autores: Juan González
• Localización: Salud mental, ISSN 0185-3325, Vol. 27, Nº. 4, 2004, págs. 6-17
• Idioma: español
• Enlaces
  • Texto completo (pdf)
• Resumen
  • español

    El presente texto analiza el concepto de recalibración perceptiva en el contexto de la epistemología prostética. Primeramente, se trata de clarificar dicho concepto y de entender, a partir de dos casos de adaptación cognitiva bien estudiados, el papel que la recalibración juega en la dinámica sensorio-motora y en la constitución de los espacios perceptivos en general. Estos son casos de interfaz humano-máquina en los que la mediación prostética y sus efectos sobre la percepción son patentes. El primer caso es presentado a través de un dispositivo de substitución sensorial, mientras que el segundo trata sobre modificación perceptiva. Posteriormente, se presentan tres implicaciones que la recalibración perceptiva tiene para la epistemología prostética y la teoría de la percepción, y que corresponden al aspecto fundamentalmente dinámico de la cognición del espacio, al aspecto indeterminado de la tipología de las modalidades sensoriales y al aspecto difuso de la frontera entre el agente cognitivo y su medioambiente.

    Sin embargo, para introducir la discusión y facilitar el análisis, primeramente esbozo un marco conceptual perteneciente a la teoría de artefactos donde distingo tres tipos de instrumentos: las prótesis, las herramientas y las extensiones especiales. Dicho marco permite clasificar tales instrumentos según sus distintos objetivos o funciones, pero también permite destacar factores comunes en ellos, como la relevancia del aprendizaje activo en su operación. Al aplicar las precisiones anteriores al ámbito de los instrumentos perceptivos, surgen ciertos rasgos que resultan relevantes para comprender tanto la naturaleza del instrumento como la importancia del circuito ¿percepción-objetivo-acción¿ en la operación del mismo. Pasando ahora a la substitución sensorial, ésta se ilustra a través de un sistema diseñado para suplir la vista a través del tacto(TVSS1).

    Después de describir brevemente dicho sistema, así como el contexto teórico de su concepción, la discusión se enfoca sobre la plasticidad cerebral y sensorial subyacentes a la operación del TVSS, haciendo resaltar que plasticidad y adaptación son conceptos que se solicitan mutuamente. El desempeño cognitivo que el TVSS facilita ¿demostrado en la adaptación exitosa del agente que lo utiliza¿ anuncia ya al concepto de recalibración perceptiva.

    Enseguida se aborda la modificación perceptiva, que es otro caso útil para ilustrar la recalibración en cuestión. Se presenta un ejemplo clásico, que consiste en la utilización de lentes de modificación visual por seres humanos. Como en el caso de la substitución sensorial, para lograr una adaptación exitosa debe realizarse un aprendizaje previo que involucra tanto una aptitud cognitiva como una actividad sensorio-motriz. Y una condición sine qua non para dicha adaptación es el ajuste o recalibración del sistema perceptivo en respuesta a exigencias funcionales cuya satisfacción permite la correcta interacción entre el agente y su medioambiente.

    Los casos de substitución sensorial y de modificación perceptiva son ilustraciones patentes de recalibración perceptiva: en ambos casos existe una adaptación, se requiere un aprendizaje para ello, la aptitud cognitiva y la actividad sensorio-motriz son fundamentales en dicho aprendizaje, la retroalimentación (o reaferencia) en el circuito ¿percepción-objetivo-acción¿ permite el ajuste, están involucradas modalidades sensoriales filogenéticamente determinadas y empíricamente ¿inicializadas¿ y, finalmente,la recalibración parece ser posible gracias a una plasticidad cerebral y sensorial subyacente. La fuerza del concepto de recalibración aquí propuesto radica principalmente en: A) la manera en que críticamente relaciono dicho concepto con sus condiciones efectivas de implementación en un contexto perceptivo, destacando entre ellas el proceso de aprendizaje activo, la plasticidad nerviosa subyacente y las exigencias funcionales correspondientes; B) el señalamiento de algunas implicaciones que dicho concepto tiene para la epistemología prostética y la teoría de la percepción.

    En relación al punto ¿B¿, y sustentadas en la discusión precedente, tres consecuencias parecen imponerse naturalmente para la epistemología prostética y la teoría de la percepción (con esta discusión concluye el artículo):

    1) La cognición espacial es fundamentalmente dinámica. Esto concierne tanto al nivel filogenético como al ontogenético y obliga a analizar la percepción como una capacidad cognitiva inextricablemente ligada a la acción;

    2) El número y el tipo de las modalidades sensoriales es revisable. En efecto, a través de instrumentos apropiados y mediante una recalibración perceptiva se pueden inaugurar modalidades sensoriales inéditas;

    3) La frontera entre el agente cognitivo y el mundo es negociable. La cognición no está confinada a los límites del cuerpo, sino que es extensible, a través de instrumentos, a un espectro de fenómenos arbitrariamente amplio y complejo.

  • English

    In this article I analyze the concept of perceptual recalibration in the context of prosthetic epistemology. The text has two main goals.

    The first one is to clarify said concept and to understand, in the light of two well-studied cases of perceptual adaptation, the role that recalibration plays in the sensorimotor dynamics of cognitive systems and in the constitution of perceptual spaces in general.

    The alluded cases involve a human-machine interface wherein prosthetic mediation and its effects on perception are evident.

    The first case concerns a sensory-substitution system, whereas the second one concerns perceptual modification lenses.

    The second goal of the text is to address three implications that perceptual recalibration has for prosthetic epistemology and, more generally, for theory of perception. The first implication concerns the all-pervasive dynamic aspect of spatial cognition;

    the second one relates to the plastic character of the sensory modalities and, hence, to the malleable character of their typology;

    the third implication addresses the constitutive vagueness of the cognitive boundary between the agent and its environment. These implications present conceptual and empirical challenges for perception theory and for theory of knowledge in general.

    I introduce the discussion by sketching a conceptual framework belonging to the theory of artifacts, according to which we can distinguish three types of instruments: prostheses, tools and special extensions. This framework is useful to classify those instruments according to their intended goals or functions, but it also proves useful to pinpoint common traits among them, such as the relevance of active learning for their operation. And by applying the previous distinctions to the domain of perceptive instruments we can gain insight as to the nature of aided perception, all the while highlighting the importance of the feed-back loop ‘perception-goal-action’ involved in the mastery and subsequent operation of instruments in general.

    The discussion then moves on to the domain of sensory substitution. This is approached through a system, called TVSS1 , designed to substitute sight through touch. After briefly describing said system, together with the theoretical context in which it was conceived, emphasis is given to the role of the brain as an interface and to the sensory plasticity that underlies the successful operation of the TVSS system. It is then posited that plasticity and adaptation are concepts that necessarily solicit each other.

    From here there is only one short step towards showing that perceptual recalibration is at work in the demonstrated cognitive performance of the agents using the TVSS system.

    Then the case of perceptual-modification lenses is addressed through the classical experiments of visual-modification prisms worn by humans, which turns out to be useful to illustrate the nature of perceptual adaptation. These experiments are relevant to the extent that, as Kohler put it, “modification casts light on development”. To this I add that development is to be understood both at the ontogenetic and the phylogenetic levels. With this in mind, it is shown that –just as it is the case in the context of sensory substitution– the concept of perceptual recalibration in this other context elegantly captures and weaves together the ideas of cognitive aptitude, adjusting sensorimotor activity and adequate responses to functional demands, which simultaneously translate as a necessary condition for a satisfactory interaction between the agent and its environment. And, again, it is claimed that plasticity and adaptation appear at work together in the process of recalibration.

    Indeed, both sensory substitution and perceptual modification clearly illustrate the process of perceptual recalibration, since in both cases there is an adaptation achieved, there is learning involved (cognitive aptitude and sensorimotor activity being fundamental for learning), reafference or feed-back in the loop ‘perception-goal-action’ allows the adjustment of the system, the sensory modalities involved –though phylogenetically determined and empirically ‘initialized’– do change their functions and/or organization in the course of time, and, finally, recalibration in both cases is made possible due to an underlying brain and sensory plasticity.

    The interest and putative strength of the concept of perceptual recalibration here introduced come mainly from: A) the way in which I critically relate such concept with its actual conditions of implementation in a perceptual context, highlighting among those conditions the active learning involved, the underlying brain and sensory plasticity and the functional demands being satisfied within a constraining environment; B) the implications that such concept has for prosthetic epistemology and, more generally, for theory of perception. The rest of the article is dedicated to expounding three of those implications.

    Implication 1: Spatial cognition is fundamentally and pervasively dynamic This claim, substantiated in the preceding discussion, is to be understood in a more radical fashion than the mere idea that cognition is accompanied by bodily movement. Indeed, this claim goes beyond the uncontroversial idea that information pick-up is done through an orderly motion of the sensory receptors, and relates to the very constituency of perceptual spaces. And it applies to both the phylogenetic and the ontogenetic levels of perceptual development. In this perspective, there is movement constantly involved all throughout the perceptual process – whether it be information pick-up, perceptual experience, perceptual learning, or even the neurobiological formation of the perceptual system itself. Hence, the perception of objects in space and of spatial relations, among other things, is made possible by the fundamentally dynamic character of our cognitive systems, whether this character be implicit in their genealogical history or explicit in their actual operation. To conclude this section, two plausible objections are raised and discussed.

    Implication 2: The number and type of sensory modalities are revisable This claim derives from the fact that, with the aid of appropriate instruments and a corresponding perceptual recalibration, it is in fact possible to modify/augment the capabilities of, and even inaugurate, sensory modalities. Although some would claim that these novel modalities (or capabilities) are not on equal epistemic footing with the classical modalities, the novel modalities, it is argued, do comply with functional and phenomenal criteria that establish them as new senses in their own right. If these criteria are accepted, then we must revise the traditional Aristotelian credo regarding the number of specialized perceptual senses humans are endowed with (presumably five), for there are assuredly more than five ways we can get particular information and experience about the world. Moreover, if the number of sensory modalities is revisable, then it seems to follow that the typology of our senses must be revisable as well –including the revision of intramodal and intermodal boundaries within the typology– making the issue about the number and type of specialized modalities there are an open, and perhaps indeterminate, matter.

    Implication 3: The cognitive boundary between the agent and the world is negotiable Cognition is not confined to the limits of our body. Occidental and industrialized common sense has it, in spite, that our skin is the definitive boundary between us and the rest of the world, and that the cognitive agent and the perceived environment are two clearly distinct things. But, again, through the use of appropriate instruments and a corresponding perceptual recalibration, it is in fact possible to extend our cognition to what prima facie is an arbitrarily complex and unlimited range of phenomena. In this way, the cognitive boundary between a perceiving agent and its surrounding environment can be displaced, depending on the purposes at hand. The limits of our cognition and, therefore, of our cognitive selfhood, are negotiable. Several examples in the text illustrate this claim. Although this epistemological negotiation should have ontological repercussions, these, however, are not addressed in the text.Implication 1: Spatial cognition is fundamentally and pervasively dynamic This claim, substantiated in the preceding discussion, is to be understood in a more radical fashion than the mere idea that cognition is accompanied by bodily movement. Indeed, this claim goes beyond the uncontroversial idea that information pick-up is done through an orderly motion of the sensory receptors, and relates to the very constituency of perceptual spaces. And it applies to both the phylogenetic and the ontogenetic levels of perceptual development. In this perspective, there is movement constantly involved all throughout the perceptual process – whether it be information pick-up, perceptual experience, perceptual learning, or even the neurobiological formation of the perceptual system itself. Hence, the perception of objects in space and of spatial relations, among other things, is made possible by the fundamentally dynamic character of our cognitive systems, whether this character be implicit in their genealogical history or explicit in their actual operation. To conclude this section, two plausible objections are raised and discussed.

    Implication 2: The number and type of sensory modalities are revisable This claim derives from the fact that, with the aid of appropriate instruments and a corresponding perceptual recalibration, it is in fact possible to modify/augment the capabilities of, and even inaugurate, sensory modalities. Although some would claim that these novel modalities (or capabilities) are not on equal epistemic footing with the classical modalities, the novel modalities, it is argued, do comply with functional and phenomenal criteria that establish them as new senses in their own right. If these criteria are accepted, then we must revise the traditional Aristotelian credo regarding the number of specialized perceptual senses humans are endowed with (presumably five), for there are assuredly more than five ways we can get particular information and experience about the world. Moreover, if the number of sensory modalities is revisable, then it seems to follow that the typology of our senses must be revisable as well –including the revision of intramodal and intermodal boundaries within the typology– making the issue about the number and type of specialized modalities there are an open, and perhaps indeterminate, matter.

    Implication 3: The cognitive boundary between the agent and the world is negotiable Cognition is not confined to the limits of our body. Occidental and industrialized common sense has it, in spite, that our skin is the definitive boundary between us and the rest of the world, and that the cognitive agent and the perceived environment are two clearly distinct things. But, again, through the use of appropriate instruments and a corresponding perceptual recalibration, it is in fact possible to extend our cognition to what prima facie is an arbitrarily complex and unlimited range of phenomena. In this way, the cognitive boundary between a perceiving agent and its surrounding environment can be displaced, depending on the purposes at hand. The limits of our cognition and, therefore, of our cognitive selfhood, are negotiable. Several examples in the text illustrate this claim. Although this epistemological negotiation should have ontological repercussions, these, however, are not addressed in the text.