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Come Back, Homunculus—All Is Forgiven!

Descartes’ view of consciousness fits the diametric model nicely.

In a previous post, I drew attention to the parallel between a particular kind of psychotic delusion and the “homuncular thinking” that has recently been found to be beneficial to autistic children. (This is not to be confused with the epigenetic homunculus, for which nothing good can be said).

The mental homunculus—a self within the brain that in some way observes itself—goes back to Descartes, and is rooted in his mind/body dualism. But the idea has not been popular either with philosophers or psychologists in recent times. On the contrary, the philosopher Daniel Dennett has relished demolishing what he contemptuously calls the Cartesian theatre model of consciousness. In particular, critics single out the infinite regress of selves-within-selves that they think the metaphor implies, and dispute the possibility of finding anything corresponding to such a set-up in the architecture of the brain (left).

Nevertheless, the Cartesian theatre has a powerful precedent in the way in which we experience vision. Even though our retinas form two separate, two-dimensional, inverted images, each with a blind spot, what we perceive is a single, three-dimensional, up-right scene with no apparent gaps. Furthermore, we see this virtual, corrected, and fabricated image of outside reality as if we were indeed sitting inside our heads and viewing it—something that becomes unmistakably obvious in the case of visual illusions, which manifestly do not simply reproduce reality. Such scenes resemble something you might see on a screen or stage, and to that extent make the theatre analogy apt and compelling, along with the implication that we must be the viewer, just as the homuncular idea suggests.

Again, the Cartesian theatre model is strikingly similar to what both psychotics and autistics report. At the very least, hearing voices and seeing hallucinations—two classic symptoms of psychosis—demonstrably demand a self to experience them, and indeed suggest an inner theatre of the mind in which they are heard or seen. Furthermore, as sufferers from such symptoms are only too well aware, their sense of being the captive audience to such sounds or scenes does not offer them any kind of regress via which to escape. On the contrary, they suffer simply because they cannot help but witness the internal psychodramas enacted inside their own minds, as I pointed out in a previous post.

A mentalistic deficit widely commented on by writers on autism—and indeed by autistics themselves—is a limited or absent sense of self as an agent responsible for your own actions. According to one such account,

One of the best ways of understanding what autism is like is to imagine yourself as a perpetual onlooker. Much of the time life is like a video, a moving film I can observe but cannot reach. The world passes in front of me shielded by glass.

Temple Grandin comments that “Using my visualization ability, I observe myself from a distance. I call this my little scientist in the corner, as if I’m a little bird watching my own behavior from up high.” She adds that this has also been reported by other people with autism and that Asperger noted that autistic children constantly observe themselves. [pp. 92-50] Such a detached, observing sense of self is also homuncular to the extent that it reproduces the Cartesian theatre symbolism of the self being essentially an onlooker, and this may explain why therapists have found homuncular symbolism of the kind described by psychotics to be valuable in treating autism, as I reported in the earlier post.

The fact that aspects of homuncular consciousness can be found in both autism and psychosis suggests that such may also be the case with normality, which after all, according to the diametric model of the mind, sits mid-way between them. The implication of the model would be that normality represents sufficient detachment from your own mentality to be able to stand back and judge the appropriateness of a mentalistic or mechanistic mode of thinking, but with sufficient subjective mentalism to avoid feeling like a mere onlooker as some autistics report, or without the excessive mentalism that made a psychotic such as Schreber look at his own mind as it were the social world around him, as explained in the earlier post.

A further argument in favor of the Cartesian theatre view of consciousness is the fact that, as I argued in another post, our conscious awareness appears to lag by a fraction of a second behind the brain mechanisms that enable it. Indeed, you could say that consciously we experience a virtual reality slightly offset from actuality by this tiny but crucial time lag. Virtual realities of this kind require an agent to perceive them, and as I argued, the agent in question is conscious choice, which, acting more like the censor than the author of our acts, can veto an entrained action just before it happens. Here again, no infinite regress of selves-within-selves applies: the whole point is that conscious choice must act quickly and decisively if it is to act at all, and the fact that it demonstrably does act like this vindicates the mental existence of a choosing homuncular self, sited in a Cartesian theatre of virtual, time-delayed reality.

Such a view of consciousness implies that there must be somewhere in the brain where “it all comes together” and consciousness occurs, and a recent discovery suggests there indeed is. As long ago as 2005, the late Francis Crick, writing with Christof Koch suggested that “the highly networked nature of the claustrum raises the question of whether it acts as a sort of ‘Cartesian theatre’.” They go on to comment that the claustrum is

a thin, irregular, sheet-like neuronal structure hidden beneath the inner surface of the neocortex in the general region of the insula. Its function is enigmatic. Its anatomy is quite remarkable in that it receives input from almost all regions of cortex and projects back to almost all regions of cortex.

Crick and Koch also point out that the claustrum “appears to be in an ideal position to integrate the most diverse kinds of information that underlie conscious perception, cognition and action.” Indeed, they add that “It is not known whether there is any one cortical region that does not receive an input from the claustrum.”

Finally, according to a recent report, a patient suffering from intractable epilepsy suddenly became unconscious during electrical stimulation of her claustrum but returned to consciousness immediately the stimulation ended. This is almost as if the claustrum were acting as an on/off switch for consciousness—and indeed as if it were the management mechanism of a mental theatre of consciousness.

You could argue that the diametric model of the mind is a neo-Cartesian one in being based on a dualistic view of cognition, and to the extent that such a model demands a discriminating, observing self to integrate and reconcile the often conflicting pictures of reality presented by mentalistic and mechanistic cognition, the Cartesian theatre seems a natural and apt metaphor of consciousness. Perhaps Descartes was right after all!

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