The sensorimotor theory of phenomenal consciousness (as proposed initially in O’Regan & Noë, 2001 and developed more extensively in (Noë, 2004; O’Regan, 2011) differs from other current theories of consciousness in a very important way: it is directly aimed at solving the “hard” problem of consciousness. To do this, the theory proposes a new, counterintuitive view about what sensory experiences or “feels” really consist of. Instead of assuming that feels are things that are generated by the brain and happen to you, the theory suggests that feels should be understood as “things that you do”. Understood this way, the quality of a feel lies in the law that describes the sensorimotor interaction involved when you experience the feel. For example, the softness of a sponge is an abstract law that describes the fact that when you press the sponge it squishes under the pressure of your fingers. Feeling the softness of the sponge involves currently being engaged in a physical interaction with the sponge and at the same time mentally probing whether at this moment your interaction obeys the sensorimotor laws of softness. More generally, having a feel with a particular quality means being currently engaged in an interaction and at the same time mentally poised to confirm that the sensorimotor laws corresponding to that quality are valid.
This approach solves one aspect of the “hard” problem of phenomenal consciousness, namely the problem of why feels feel the the way they do. It is no longer necessary to postulate as-yet-undiscovered brain mechanisms that generate feels of different qualities. Instead, explaining the quality of feels simply involves describing the differences in sensorimotor laws that correspond to the different feels. For example, vision feels different from audition because sensorimotor input from seeing depends differently on your movements than from hearing (for example if you blink there is an abrupt change in visual input but not in auditory input).
But how can merely mentally probing your current engagement with the world and the accompanying sensorimotor law explain why feels “feel like something”? The sensorimotor theory approaches this second aspect of the “hard problem” by noting that when you are engaging with the world, the sensorimotor laws that govern such engagements have three special properties: bodiliness, insubordinateness, and grabbiness. Bodiliness is the fact that a body movement necessarily modifies sensory input corresponding to the feel. Insubordinateness is the fact that sensory inputs corresponding to feels from the outside world can also change without the body moving. And grabbiness corresponds to the fact that sensory systems are hard-wired by evolution to interrupt cognitive processing (for example a sudden loud noise, bright flash, etc.).
Because of these properties, when you are engaged in sensory experiences, you have the impression of being mentally and physically subjected to them, rather than fully controlling them as is the case for purely mental activities. This gives you the impression of something happening to you, and imposing itself on you. The sensorimotor approach suggests that this may be very close to what people mean when they say it “feels like something” to have a phenomenal experience.
So does the sensorimotor theory bridge the explanatory gap and solve the hard problem? The claim is that it does. There remain tricky issues like how to account for hearing and smell, for example, that involve only a small amount of bodily motion. But progress is being made, and even feels like the pure redness of red are yielding to the approach (Philipona & O’Regan, 2006) — all this makes it unnecessary to postulate obscure mechanisms like quantum gravity effects in microtubules, recurrent oscillations in cortico-thalamic networks, or information integration, etc. as somehow “generating” the what it’s like of feels. The approach is also scientifically productive, making predictions and impulsing research in domains like change blindness, illusions of body ownership, color, and sensory substitution.
But what about other aspects of consciousness? Questions of “conscious access” are not the focus of the sensorimotor approach. For example, whether or not you perceive a stimulation under given presentation conditions, and how this is implemented in neural circuits is something that the theory leaves to psychologists and neurophysiologists. The “self” is another issue that is not the focus of the sensorimotor theory. “Who” is it that is consciously experiencing a feel? The sensorimotor approach assumes that an account of the self can be given in terms of known social and cognitive mechanisms.
Does the sensorimotor approach to qualia have affinities with “illusionist” approaches? The approach is not illusionist in the sense of Frankish, who suggests that the brain manufactures the illusion of phenomenality for sensory states. The sensorimotor approach considers on the contrary that there is no illusion being fabricated by the brain. The interactions with the world that we call “feels” do indeed have the qualities that we attribute to them: they are subjective (because we are doing them ourselves), ineffable (because we cannot describe all the infinite number of sensorimotor laws that underlie them — can you say, for example what exactly you do with your tongue when you whistle?), and they feel like something to us (because they impose themselves on our minds in a certain way that leads us to say that we are engaged with the world and feel them rather just know them). While the sensorimotor approach shares Dennett’s view that the notion of qualia is logically incoherent, again, the sensorimotor view is that there is nevertheless much to be said about the quality of sensory experiences (for example, how they differ and are similar, or to what extent they have phenomenal “presence” and feel like something), and these things can be explained scientifically and are not illusory (O’Regan, 2010).