This is a comment on J. K. O’Regan. and Alva Noë, "A Sensorimotor Account of Vision and Visual Consciousness" Both their paper and my comment are forthcoming in The Behavioral and Brain Sciences

Behaviorism Revisited

Ned Block, Professor
Departments of Philosophy and Psychology
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Abstract: Behaviorism is a dead doctrine that was abandoned for good reason.  A major strand of O’Regan’s and Nöe’s view turns out to be a type of behaviorism, though of a non-standard sort.  However, the view succumbs to some of the usual criticisms of behaviorism.

O'Regan and Noe declare that the qualitative character of experience is constituted by the nature of the sensorimotor contingencies at play when we perceive.  Sensorimotor contingencies are a highly restricted set of input-output relations.  The restriction excludes contingencies that don’t essentially involve perceptual systems.    Of course if the ‘sensory’ in ‘sensorimotor’ were to be understood mentalistically, the thesis would not be of much interest, so I assume that these contingencies are to be understood non-mentalistically. Contrary to their view, experience is a matter of what mediates between input and output, not input-output relations all by themselves.  However, instead of mounting a head-on collision with their view, I think it will be more useful to consider a consequence of their view that admits of obvious counterexamples.  The consequence consists of two claims: (1) any two systems that share that highly restricted set of input-output relations are therefor experientially the same and (2)  conversely, any two systems that share experience must share these sensorimotor contingencies.  Once stated, the view is so clearly wrong that my ascription of it to them might be challenged.  At least it is a consequence of a major strand in their view.  Perhaps this will be an opportunity for them to disassociate themselves from it.   I will limit myself to (1).

There are some unfortunate people whose visual apparatus has been severely damaged to the point where they can distinguish only a few shades of light and dark. You can simulate this “legally blind” state at home, though imperfectly,  by cutting a ping-pong ball in half and placing one half over each eye.  In addition, many people are paralyzed to the point where they can control only a very limited set of behaviors, e.g. eye-blinks.  For someone who has both problems, visual sensorimotor contingencies are drastically reduced.  In fact, it would seem that they are so reduced that they could be written down and programmed into an ordinary laptop computer of the sort we find in many briefcases.  If this were done, O’Regan’s and Noe’s thesis would commit them to the claim that the laptop has experiences like those of the legally blind paralytic I mentioned.  (This form of argument derives from my reply to Dennett in Block, 1995a (p. 273) and has been subsequently used by Siewart, 1998.)
What would those experiences of the laptop have to be like?  Well, if you put the ping-pong balls on your eyes you can get some insight into the matter yourself.   My judgement is that such experiences are no less vivid than ordinary experience although of course greatly reduced in informational content. Perhaps O & N will say that the paralysis dims the experience to the point where it is not so implausible that the laptop has it. However, people who are temporarily completely paralyzed often report normal experience during the paralyzed period.   In any case, can there be any doubt that such people do have some experience, even visual experience, and the laptop has no experience at all?  I would say the same for people who are born with severe limits to their visual apparatus but report visual experience with low informational content.  There is every reason to think that these people have some visual experience and that the corresponding laptop has none.

Behaviorism in one form is the view that two systems are mentally the same just in case they are the same in input-output capacities and dispositions.  There are standard refutations of behaviorism.  (See for example, Block 1995b, 377-384 or Braddon-Mitchell and Jackson 1996, pp. 29-40 and 111-121.)  But what really killed behaviorism was the rise of the computer model of cognition.  If cognitive states are computational states of certain sorts, behaviorism runs into the problem that quite different computational states  of the relevant sort can be input-output equivalent.  For example, consider two input-output equivalent computers that solve arithmetic problems framed in decimal notation.  One  does the computation in decimal whereas the other translates into binary, does the computation in binary and then translates back into decimal.  Delays are added to get the two computations to have the same temporal properties.  Behaviorism died because it didn’t fit with the computational picture of cognition.  Putting the point dramatically and over-simply, behaviorism died because it isn’t true even of computers!

O & N’s view as I am interpreting it is a form of behaviorism.  It isn’t the general behaviorism that I just described because it is about sensory experience, not cognition and not mentality in general.  And so it might be thought to escape the problem just mentioned.  Since it is not about cognition, O & N don’t have to worry about two different cognitive states being input-output equivalent or two identical cognitive states implemented in systems with different input-output relations.  But their view is doomed by a similar problem nonetheless: the same input-output relations can be  mediated either by genuine experience or by simple computations that involve no experience.  Genuine experience need not have a complex computational role, and that less complex experience surely can be simulated in input-output terms by a system that has no experience.


Block, Ned, 1995a.  "How Many Concepts of Consciousness?" in The Behavioral and Brain Sciences 18, 2, pp. 272-284

Block, Ned, 1995b.  “The Mind as the Software of the Brain”, An Invitation to Cognitive Science, edited by D. Osherson, L. Gleitman, S. Kosslyn, E. Smith and S. Sternberg, MIT Press.

Braddon-Mitchell, David and Jackson, Frank, 1996.  Philosophy of Mind and Cognition, Blackwell: Oxford.

Siewart, Charles, 1998. the Significance of ConsciousnessPrinceton University Press: Princeton.