Journal of Consciousness Studies
jcs-online thread:
Synchronous Oscillations and the Emperor's New Clothers

How Can we Explain the Unity of Conscious Experience?

Benjamin Libet, Department of Physiology, UCSF

Keith Sutherland (1996) has written a formidable and well-reasoned critique of the proposition (by Metzinger and others) that synchronous oscillations (of electrical potentials) in diverse neuronal groups results in perceptual binding and even in the unified phenonenal self. As I have produced a completely opposed (top down) proposal (Libet, 1994), I should like to restate the argument from my perspective, and show how my proposed "conscious mental field" (CMF) fits in.

It is useful to consider all such proposals with at least two separate kinds of criteria - the scientific ones and the philosophical ones (that make no pretense of being experimentally testable).

As a scientific proposal the "synchrony theory" is very deficient. There is at present no evidence to support the view that the observed synchronizations actually are a causative mediator of either perceptual binding or phenomenal unity of conscious sensory experience. The proponents of the synchrony role should at least produce a design for an experimental test, one that includes a potentiality for falsifying the proposal. If and when such an experiment is designed, it must be recognized that a test for perceptual binding would not tell us about the unity of conscious subjective experience, unless evidence for the latter from introspective reports is included. I would note that my proposal for a CMF was accompanied by a fully elaborated experimental design that achieved such requirements.

Now, as to the more purely philosophic aspects of theories to explain subjective unity: How does one get from synchrony of neuronal oscillations to a unified conscious sensation? Sutherland produces an appropriate criticism of any such bottom-up approach.

Then there is the "widespread belief within the cognitive sciences [and I would add cognitive philosophers] that the phenomenal self is a constructed illusion." This is partly due to a robust "homuphobia" - as Sutherland aptly puts it. I agree fully with him that "in the field of human consciousness it is better to start with our own experience rather than dogma". Indeed the primacy of the subjects' reported experiences was a stated and practiced feature in our experimental work on the relation between cerebral (physical) and conscious mental processes (e.g. Libet 1985, see p.559). Theories are supposed to explain facts, not eliminate or distort them without compelling evidence to justify that.

If it is proposed that subjective experience and the phenomenal self are constructed illusions, then we should ask "Who is observing this illusion?" I agree with Sutherland that we must not accept the panicking fear, of most philosophers and probably cognitive scientists, that any theory must exorcise any implied "ghost of agency". Theories that avoid any "ghost" have not successfully or convincingly explained the unity of conscious experience and the experience of conscious control of voluntary acts. Postulating a subjective "ghost" need not be incompatible with the laws of nature, as Schroedinger pointed out.

The conscious mental field (CMF), that I have postulated to account for the unity of experience and an active role for conscious intention to act, could be viewed as a sort of "ghost". However, it is supposed to emerge from suitable natural activities of cerebral neurons, but with *de novo* properties not evident in the physical neural elements from which it derived. Some people may wish to call this dualism, but let us not be frightened off by name calling. The CMF does not represent the dualism of Descartes, who described the mind as a separable substance. My CMF proposal is of course very speculative. But I do not know of any existing evidence that contradicts the proposal, and, furthermore, it is amenable to a direct experimental test of its validity.

References

Libet, B. (1994), "A testable field theory of mind-brain interaction", Journal of Consciousness Studies, 1(1) pp. 119-126.

Libet, B. (1985), "Unconscious cerebral initiative and the role of conscious will in voluntary action", Behavioral and Brain Sciences, 8, pp. 529-566.

Sutherland, K. (1996), "Synchronous Oscillations and the Emperor's New Clothes"


Onlinejcs-online menu