Recuperamos este artículo de 2015, con una addenda de Dennett:
sábado, 21 de marzo de 2015
La proyección mental de la realidad
La sustancia (y ya lo dijo en cierto modo Berkeley) es que el objeto visual es construido por el cerebro, no "recibido" ya hecho desde el exterior. Yo lo llamo a veces la teoría de la "proyección del objeto", porque el efecto viene a ser como si nuestro cerebro proyectase a la realidad el objeto que ha generado, con el resultado de que lo vemos allí afuera, cuando no está sino en nuestra cabeza. Quizá sea más apropiado llamarla, como lo hacen estos autores, la teoría de la "integración del objeto."
Integration Trumps Selection in Object Recognition
http://www.cell.com/current-biology/abstract/S0960-9822%2815%2900132-3Highlights
- •Humans identified letter shapes defined by texture, color, and luminance cues
- •Humans integrate cues that define the same letter for improved shape recognition
- •They cannot filter out cues that define a conflicting letter, reducing performance
- •Mandatory cue integration results in a failure of attentional selection
Summary
Finding and recognizing objects is a fundamental task of vision. Objects can be defined by several “cues” (color, luminance, texture, etc.), and humans can integrate sensory cues to improve detection and recognition [ 1–3 ]. Cortical mechanisms fuse information from multiple cues [ 4 ], and shape-selective neural mechanisms can display cue invariance by responding to a given shape independent of the visual cue defining it [ 5–8 ]. Selective attention, in contrast, improves recognition by isolating a subset of the visual information [ 9 ]. Humans can select single features (red or vertical) within a perceptual dimension (color or orientation), giving faster and more accurate responses to items having the attended feature [ 10, 11 ]. Attention elevates neural responses and sharpens neural tuning to the attended feature, as shown by studies in psychophysics and modeling [ 11, 12 ], imaging [ 13–16 ], and single-cell and neural population recordings [ 17, 18 ]. Besides single features, attention can select whole objects [ 19–21 ]. Objects are among the suggested “units” of attention because attention to a single feature of an object causes the selection of all of its features [ 19–21 ]. Here, we pit integration against attentional selection in object recognition. We find, first, that humans can integrate information near optimally from several perceptual dimensions (color, texture, luminance) to improve recognition. They cannot, however, isolate a single dimension even when the other dimensions provide task-irrelevant, potentially conflicting information. For object recognition, it appears that there is mandatory integration of information from multiple dimensions of visual experience. The advantage afforded by this integration, however, comes at the expense of attentional selection.Este tipo de integración cognitiva en el cerebro resulta (claro está) de su complejidad de circuitos neuronales que procesan diversa información, parte proveniente del córtex, de la memoria, combinándola con "lo que se ve." Resulta de la historia evolutiva del cerebro, y en parte de su "recableo" provocado por la ampliación del córtex y la integración de la información lingüística en la estructura del cerebro. Más al respecto hablan Deacon (ver La caverna del cerebro) y Benjamin Bergen en Louder than Words. La estructura del cerebro, el desarrollo del lenguaje y la integración de nuestra cultura y experiencia con nuestra percepción generan así la realidad virtual o realidad aumentada donde vivimos. Para otros seres con ojos no está ahí—pero nosotros la vemos; y es más, nos movemos por ella y vivimos en ella.
La noción de estroma propuesta por Gustavo Bueno viene a ser una manera de enfocar el mismo fenómeno, visto desde su teoría. El "estroma" es el objeto cultural, el meme mental podríamos decir, que tiene una naturaleza cognitiva e informacional pero a la vez es un objeto físico. Esto da lugar a una ontología de objetos materiales gestionados y organizados por la mente.
Hablaba yo de esta cuestión de la generación mental de la realidad, a cuenta del libro de Weiskrantz Consciousness Lost and Found, de Gazzaniga, y de las neuronas espejo, y defendiendo la tesis de la "proyección" o de la "realidad proyectada", en ESPECULACIONES NEURONALES.
Esta cuestión de neurología, de lingüística y de psicología cognitiva también tiene implicaciones filosóficas, fenomenológicas y antropológicas, claro está. Así que por qué no añadir un ingrediente más al cocido de este artículo, relacionando esta noción de la realidad aumentada gestada en el cerebro, con la teoría de la mente y de la experiencia de George Herbert Mead, que veníamos discutiendo estos días por aquí también. Entre pragmatismo y fenomenología anda la cosa, pero más que rozando la metafísica, puesto que Mead pretende explicar la generación misma de la realidad, de la realidad espacio-temporal (esos irreductibles kantianos) a través del análisis de la experiencia de contacto, y explicando la genesis del tiempo mediante la auto-interacción. En fin, se lo lean en Mind, Self and Society o en La Filosofía del presente. Mead se vio influido por muchos (Dilthey, Wundt, James, Dewey, Bergson, etc.) pero muy inmediatamente aquí por las reflexiones de Alfred North Whitehead en What Is Nature. (Oigan aquí un podcast sobre la teoría de la constitución mental de la realidad del propio Whitehead, que a su vez nos lleva más atrás—a Locke, etc.). Pero dejaremos para otra ocasión, quizá para la eternidad, la teoría de la Realidad como Realidad Virtual y la organización mental del mundo según Whitehead.
Aquí sólo traeré a colación un par de textos relevantes de Mind, Self, and Society de Mead, el primero en realidad de uno de los ensayos suplementarios llamado "El individuo biológico":
From the point of view of instinctive
behavior in the lower animals, or of the immediate human response to a
perceptual world (in other words, from the standpoint of the
unfractured relation between the impulses and the objects which give
them expression), past and future are not there; and yet they are
represented in the situation. They are represented by facility of
adjustment through the selection of certain elements both in the direct
sensuous stimulation through the excitement of the end-organs, and in
the imagery. What represents past and what represents future are not
distinguishable as contents. The surrogate of the past is the actual
adjustment of the impulse to the object as stimulus. The surrogate of
the future is the control which the changing field of experience during
the act maintains over its execution.
The flow of experience is not differentiated into a past and future over against an immediate now until reflection affects certain parts of the experience with these characters, with the perfection of adjustment on the one hand, and with the shifting control on the other. The biologic individual lives in an undifferentiated now; the social reflective individual takes this up into a flow of experience within which strands a fixed past and a more or less uncertain future. The now of experience is represented primarily by the body of impulses listed above, our inherited adjustment to a physical and social world, continuously reconstituted by social reflective processes; but this reconstitution takes place by analysis and selection in the field of stimulation, not by immediate direction and recombination of the impulses. The control exercised over the impulses is always through selection of stimulations conditioned by the sensitizing influence of various other impulses seeking expression. The immediacy of the now is never lost, and the biologic individual stands as the unquestioned reality in the minds of differently constructed pasts and projected futures. It has been the work of scientific reflection to isolate certain of these fixed adjustments (in terms of our balanced postures, our movements toward objects, our contacts with and manipulations of objects) as a physical world, answering to the biologic individual with its intricate nervous system. (350-51)
The flow of experience is not differentiated into a past and future over against an immediate now until reflection affects certain parts of the experience with these characters, with the perfection of adjustment on the one hand, and with the shifting control on the other. The biologic individual lives in an undifferentiated now; the social reflective individual takes this up into a flow of experience within which strands a fixed past and a more or less uncertain future. The now of experience is represented primarily by the body of impulses listed above, our inherited adjustment to a physical and social world, continuously reconstituted by social reflective processes; but this reconstitution takes place by analysis and selection in the field of stimulation, not by immediate direction and recombination of the impulses. The control exercised over the impulses is always through selection of stimulations conditioned by the sensitizing influence of various other impulses seeking expression. The immediacy of the now is never lost, and the biologic individual stands as the unquestioned reality in the minds of differently constructed pasts and projected futures. It has been the work of scientific reflection to isolate certain of these fixed adjustments (in terms of our balanced postures, our movements toward objects, our contacts with and manipulations of objects) as a physical world, answering to the biologic individual with its intricate nervous system. (350-51)
Y en la primera mitad de Mind, Self, and Society, habla de cómo la mente y la consciencia no están localizadas en ningún punto concreto del cerebro, sino que son el resultado emergente de la interacción de los circuitos cerebrales entre sí:
In the cortex, that organ which in some
sense answers to human intelligence, we fail to find any exclusive and
unvarying control, that is, any evidence of it in the structure of the
form itself. In some way we can assume that the cortex acts as a whole,
but we cannot come back to certain centers and say that this is where
the mind is lodged in thinking and in action. There are an indefinite
number of cells connected with each other, and their innervation in
some sense leads to a unitary action, but what that unity is in terms
of the central nervous system it is almost impossible to state. All the
different parts of the cortex seem to be involved in everything that
happens. All the stimuli that reach the brain are reflected into all
parts of the brain, and yet we do get a unitary action. There remains,
then, a problem which is by no means definitely solved: the unity of
the action of the central nervous system. Wundt undertook to find
certain centers which would be responsible for this sort of unity, but
there is notheing in the structure of the brain itself which isolated
any parts of the brain as those which direct conduct as a whole. The
unity is a unity of integration, though just how this integration takes
place in detail we cannot say. (24)
Now behavioristic psychology, instead of setting up these events in the central nervous system as a causal series which is at least conditional to the sensory experience, takes the entire response to the environment as that which answers to the colored object we see, in this case the light. It does not locate the experience at any point in the nervous system; it does not put it, in the terms of Mr. Russell, inside of a head. Russell makes the experience the effect of what happens at that point where a causal process takes place in the head. He points out that, from his own point of view, the head inside of which you can place this experience exists empirically only in the heads of other people. The physiologist explains to you where this excitement is taking place. He sees the head he is demonstrating to you and he sees what is inside of the head in imagination, but, on this account, that which he sees must be inside of his own head. The way in which Russell gets out of this mess is by saying that the head which he is referring to is not the head we see, but the head which is implied in physiological analysis. Well, instead of assuming that the experienced world as such is inside of a head, located at that point at which certain nervous disturbances are going on, what the behaviorist does is to relate the world of experience to the whole act of the organism. It is true, as we have just said, that this experienced world does not appear except when the various excitements reach certain points in the central nervous system; it is also true that if you cut off any of those channels you wipe out so much of that world. What the behaviorist does, or ought to do, is to take the complete act, the whole process of conduct, as the unit in his account. In doing that he has to take into account not simply the nervous system but also the rest of the organism, for the nervous system is only a specialized part of the entire organism. (111)
Now behavioristic psychology, instead of setting up these events in the central nervous system as a causal series which is at least conditional to the sensory experience, takes the entire response to the environment as that which answers to the colored object we see, in this case the light. It does not locate the experience at any point in the nervous system; it does not put it, in the terms of Mr. Russell, inside of a head. Russell makes the experience the effect of what happens at that point where a causal process takes place in the head. He points out that, from his own point of view, the head inside of which you can place this experience exists empirically only in the heads of other people. The physiologist explains to you where this excitement is taking place. He sees the head he is demonstrating to you and he sees what is inside of the head in imagination, but, on this account, that which he sees must be inside of his own head. The way in which Russell gets out of this mess is by saying that the head which he is referring to is not the head we see, but the head which is implied in physiological analysis. Well, instead of assuming that the experienced world as such is inside of a head, located at that point at which certain nervous disturbances are going on, what the behaviorist does is to relate the world of experience to the whole act of the organism. It is true, as we have just said, that this experienced world does not appear except when the various excitements reach certain points in the central nervous system; it is also true that if you cut off any of those channels you wipe out so much of that world. What the behaviorist does, or ought to do, is to take the complete act, the whole process of conduct, as the unit in his account. In doing that he has to take into account not simply the nervous system but also the rest of the organism, for the nervous system is only a specialized part of the entire organism. (111)
_____
Más sobre percepción, reconocimiento y constitución perceptual de los objetos en esta conferencia de Ned Block: Seeing-as, Concepts, and Non-conceptual Content
—oOo—
Addenda (2025):
Un pasaje del libro de Daniel Dennett From Bacteria to Bach and Back (p. 356-58), donde retoma la idea y el término de "proyección" para describir este fenómeno de interacción entre la consciencia y la realidad percibida, lo mismo que Zubiri llama percepción intelectiva, o lo que Hobbes describe como esa especie de sueño despierto que es la generación de la realidad y del efecto de realidad en la mente.
Ver:
_____. "Impresión de realidad: La percepción intelectiva en la epistemología de Zubiri." SSRN 23 June 2021.*
http://ssrn.com/abstract=3866299.
2021
_____. "Lo mismo despiertos, que soñando: Hobbes sobre la virtualidad de lo real." Academia 25 Feb. 2017.*
https://www.academia.edu/31599964/
2017
Bien, pues he aquí un pasaje en el que Dennett describe la consciencia como una ilusión generada para el usuario de la misma ("Consciousness as an evolved user-illusion") usando la analogía de la proyección.
It is how our brainsrespond that causes "us" (in the manifest image) to "project" an illusory property into the (manifest) world. There are structural, chemical properties of glucose—mimicked in saccharine and other artificial sweeteners—that cause the sweetness response in our nervous systems but "the intrinsic, subjective sweetness I enjoy" is not an internal recreation or model of these chemical properties, nor is it a very special property in our non-physical minds that we use to decorate the perceptible things out there in the world. It is no property at all; it is a benign illusion. Our brains have tricked us into having the conviction, making the judgment, that there seems to bean intrinsically wonderful but otherwise undescribable property in some edible things: sweetness. We hcan recognize it, recall it, dream about it, but we can't describe it; it is ineffable and unanalyzable.
There is no more familiar and appealing verb than "project" to describe this effect, but of course everybody knows it is only metaphorical; colors aren't literally projected (as if from a slide projector) out onto the front surfaces of (colorless) objects, any more than the idea of causation is somehow beamed out onto the point of impact between billiard balls. If we use the shorthand term "projection" to try to talk, metaphorically, about the mismatch between manifest and scientific image here, what is the true long story? What is literally going on in the scientific image? A large part of the answer emerges, I propose, from the predictive coding perspective we explored briefly in chapter 8 (How do brains pick up affordances?)
Here is where Bayesian expectations can play an iterated role: our ontology (in the elevator sense) does a close-to-optimal job of cataloguing the things in the world that matter to the behavior our brains have to control. Hierarchical Bayesian predictions accomplish this, generating affordances galore: we expect solid objects to have backs that will come into view as we alk around them, doors to open, stairs to afford climbing, cups to hold liquid, and so forth. But among the things in our Umwelt that matter to our well-being are ourselves! We ought to have good Bayesian expectations about what we will do next, what we will think next, and what we will expect next! And we do. Here's an example:
Think of the cuteness of babies. It is not, of course, an "intrinsic" property of babies, though it seems to be. What you "project" onto the baby is in fact your manifold of "felt" dispositions to cuddle, protect, nurture, kiss, coo over,... that little cutie-pie. It's not just that when your cuteness detector (based on facial proportions, etc.) fires, you have urges to nurture and protect; you expect to have those very urges, and that manifold of expectations just is the "projection" onto the baby of the property of cuteness. When we expect to see a baby in the crib, we also expect to "find it cute"—that is, we expect to expect to feel the urge to cuddle it and so forth. When our expectations are fulfilled, the absence of prediction-error signals is interpreted by our brains as confirmation that, indeed, the thing in the world we are interacting with really has the properties we expected it to have. Cuteness as a property passes the Bayesian test for being an objective structural part of the world we live in, and that is all that needs to happen. Any further "projection" process would be redundant. What is special about properties like sweetness and cuteness is that their perception depends on particularities of the nervous systems that have evolved to make much of them. They have a biased or privileged role in the modulation of our control systems—we care about them, in short.
Here we must be very careful not to confuse two independent claims. The properties of sweetness and cuteness depend on features of our nervous systems and hence are in that limited sense subjective, but that must not be taken to mean that sweetness, say, is an intrinsic (subjective) property of conscious experience! Hume's strange inversion is wonderful but incomplete: when he spoke of the mind's "great propensity to spread itself on external objects," this should be seen not as a stopping point but as a stepping-stone to a further inversion. Hume's image nbrilliantly conjures up the curious vision of the mind painting the external world with the propietary ("intrinsic") hues properly worn by the mind's internal items.—impressions and ideas, in his vocabulary. But there is no such paint (which is why I once dubbed it "figment"). We need to push Hume's inversion a little harder and show that the icons of the user-illusion of our minds, unlike the user-illusion of our computers, don't need to be rendered on a screen.
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