Under the title 'Do mental events exist: Physiological adumbrations', this paper was originally published in the British Journal of Psychiatry, 1972, 120, 129-132. The abstract originally appeared in the November 1971 issue of the same journal.
DO MENTAL EVENTS EXIST OR IS MAN JUST A
PROTEIN MACHINE?
J. J. Ray
It is argued that the present state of neurophysiological knowledge and theory does give grounds for an explanation of all those phenomena normally held in some quarters to be irreducibly 'mental'. Suggestions are made as to what physiological events particular mental events could be made up of. It is proposed that perception should be regarded as a response and that the problem, 'What is consciousness?' should be treated as an empirical one -- the tentative answer proposed being: 'All those responses accompanied by an orienting response'. It is concluded that peculiarly "mental" events do not exist.
IN THIS PAPER, elaboration of a Realist answer to some of the classical questions of psychology and epistemology will be sought, starting from a knowledge of Soviet and Western findings in psychophysiology (particularly the work of Pavlov, 1932, and Hebb, 1949. See also the summary by Burt, 1968). The point of departure taken in the philosophical literature is the paper by Place (1969). This paper will adopt a reflexological model of brain function -- with its implied view that memory is synaptically encoded. While this model has largely fallen into disfavour, it is used here paradigmatically -- to show that well-developed physiological models in general can provide a satisfactory account of 'mental' phenomena.
The central expository device to be used here is theoretical consideration of a man who has had a microelectrode inserted in each cell of his CNS, each of these being connected to one of a vast array of oscilloscopes situated in front of him in a manner such that he can see at all times a representation of the electrical events going on in his brain. While such a preparation is not technically possible at the moment, the day when it may definitely be possible does not seem so far off at all against the historical perspective of the two or more millennia in which questions of epistemology have been discussed. Nonetheless the technical possibility as such is really irrelevant here. Such a preparation is considered merely for its value as a model. It will be evident that with such a preparation we would be able to determine exactly what brain processes go on when particular mental events go on. In this paper, an attempt to predict the type of answers we would get will be made on the basis of present neurophysiological knowledge and theory. There will then follow some consideration of questions more purely epistemological in nature.
A few stipulative definitions to start with: When 'stimulus' is used here, it will be used to mean any event which causes a neuron to discharge with a spike potential ('neuron' here will include those specialised cells which make up the classical sensory receptors). A discharge across a neuro-muscular synapse will also be called a stimulus (to muscle fibres). 'Response' will be used here to mean a spike potential in any neuron or a contraction in any muscle tissue. From this definition, it will be obvious that the stimulus to one neuron or muscle fibre will very often be a part of the response of another neuron or muscle fibre. A 'reflex' will be used to refer to a structural feature of nervous tissue which predisposes one particular neuron or set of neurons to fire another particular neuron or muscle fibre (out of the many particular adjacent neurons or muscle fibres it could possibly fire).
Let us go back now to our man with the wired-up brain. The responses shown on the oscilloscope are set up with a three-second time lag. He looks at a plain blue surface and then quickly looks at his oscilloscope array to find out what happened in his brain when he saw 'blue'. He sees a myriad of events going on, all over his brain. Not discouraged he looks again and again at a series of objects all of the same blue shade. Eventually he notes that of all the brain events going on there is one and only one which coincides always with his seeing blue and which never occurs without his seeing blue. What then might he say? He might say: 'Now I know what blue is' or 'Now I know what causes me to perceive blue' or 'Now I know what the perception of blue is made up of'. While we might feel confident of our ability to convince him that the first two of these statements need revision, it seems to me that, in the third statement, all people but some philosophers would agree that our man is right and his statement is accurate. But such a statement implies that the total set of brain events is the perception of blue, that a perception is a brain process. Only the object perceived is blue. There is no need of an internal analogue to represent blue. To perceive blue is to respond in a certain way to a blue object. Even in dreams, what we see are things -- not images. What does need explaining in dreams is that we see things at a time when those things are not present. The explanation of this is merely a particular technical problem. So perceiving that a thing is blue is not the same as seeing the brain process that goes on when a person perceives blue -- nor should it be. Blue is a property of the object. Perceiving is an activity of organisms. Accurate perceptions are adaptive responses in organisms, and misperceptions are unadaptive responses in organisms. (A part of the reason why they are unadaptive is that they set off stimulus-response chains which may call for opposing effector actions at any one point in time.)
The above is tantamount to a denial that there are mental events. When we close our eyes (and other receptors) what 'mental' events might go on? We could 'call up an image of an object' -- which is not quite like seeing an object. This is conceivably a conditioned response to a sub-vocalised or even non-vocalised verbal stimulus --and, like all conditioned responses, not quite like the unconditioned response. We do in fact 'see' a modified object because brain activity goes on in accordance with known conditions for brain activity.
To move out of the visual modality, we could also claim that we hear our own thoughts quite clearly. This testifies to the strength of the auditory conditioned responses to (sub-verbal) speech. At other times, brain activity may go on without verbalisations (or any 'central' part thereof), but while in retrospect we may feel that something went on, we cannot 'say' what it was -- i.e. in this sense there was 'imageless' (or non-verbal) thought. 'Imageless thought' then is any brain process not involving sub-vocal verbalisations or conditioned response perceptions of objects.
Why is it that only some responses are 'conscious'? When we 'see' an object a response takes place that has the quality of 'consciousness'. Why do not all our responses have this quality? The short answer is again that this would be unadaptive. Particular perceptual responses have their stimulus properties magnified by another, concurrent 'orienting response' (Lynn, 1966). This 'orienting response' is a stereotyped set of physiological changes which occur in various degrees after stimuli of certain strength. As so far measured, it has always peripheral components, but in the case of weak stimuli there may be a purely central form of the response with no peripheral indicators. It is stimuli eliciting orienting responses that we describe ourselves as being 'aware of or 'conscious of . Thus, when we open our eyes we respond to or perceive all the things before us. The strongest of all these responses however, will be accompanied by another, orienting, response and it is this strongest of responses which is conscious perception. For a person to be said to be conscious, orienting responses must be taking place in his central nervous system.
Just as I become 'conscious' of objects in the external world, so I may become 'aware' of my own responses. Each response acts in turn as a stimulus for another response. That a response is triggered off is perception. If this response is accompanied by another, orienting response, I then become 'aware' of my original action. Thus I may come to 'know that I know' -- when the perceptual response accompanied by an orienting response becomes itself a stimulus for a further response of like nature. At this point it becomes possible to define 'perceptual' versus 'non-perceptual' responses. A perceptual response is one that an orienting response could magnify. In humans, this is mainly the class of responses occurring in the cerebral cortex. Note that the difficulty of demonstrating unconscious conditioning is paralleled by the difficulty of demonstrating sub-cortical conditioning.
From the foregoing it follows that while it may be true that we describe a disposition of a person when we say 'he knows something', to say that 'he came to know something' is not to describe a disposition he had but rather to assert that he had an orienting and a perceptual response to a particular event that caused structural alterations in his brain; i.e. from that point on a reflex was established which was the mechanism for his having in future a disposition to respond in a way different to the way he would have responded had that perception never occurred.
In vision, how is it that we see objects, although it is a light wave that actually produces the receptor response, i.e. how is it that we know the object to be 'out there' and not on our retina? This is an inference the brain learns to make using several cues. How does it learn? Reflexes are set up by the coincidence of certain visual cues with tactile stimuli. Distance receptors evolved subsequent to contact receptors and hence touch is the 'final check' (unconditioned stimulus) of visual impressions (compare our responses when confronted with the 'bent stick' illusion in water). Thus responses to tactile stimulus could be said to form first-order conditioned reflexes while some responses to visual cues are formed as second order or 'generalised' reflexes. Note, however, that the distinction between touch and distance receptors is only one of the nature of the characteristic stimulus. In both cases stimuli cause us to 'perceive' (or: 'react to') objects. The difference is that in one case. we believe the stimulus event to involve only the object perceived (touch), whereas in the case of the distance receptors we have to learn otherwise.
The inferences necessary with distance receptors may of course fail when the needed cues are attenuated. This has often been shown in distance perception and size constancy experiments. This shows that the 'inference' is in fact a conditioned response as dependent on appropriate stimuli as any other conditioned response. To say the 'brain infers distance' is to say that we respond as if the thing perceived were not touching our receptors. This is what the perceiving of a thing 'out there' is. We respond in such a way because that has been both learnt and selected for in evolution -- and the reason such a response has been learnt and selected for in evolution is that the object really is 'out there'.
But when it is asserted that perception is made up of neural responses and nothing more, someone will want to claim that Watson (the founder of behaviourism) was discredited for just such an assertion when he denied that mental events exist. This is not so. The failure of Watson was not that he denied mental events but that he also acted as if brain processes too did not exist. Watson acted as if he believed that the only responses and stimuli which existed were those observable from outside the organism without the aid of instruments. The remarks made here, on the other hand, if they have any implications for the direction of future psychological research, point rather to the importance of introspection, free association and other techniques which stimulate and disinhibit vocal muscle responses to neural outputs from the brain.
I will, however, heartily concur with Watson in claiming that mental events do not exist. How do we know there are mental events unless we perceive them? But how could we perceive them? We perceive objects and some of our own physio-chemical processes, but if one defines mental events as something beyond physiochemical processes or objects then how can they be perceived? How can one know them? If mental events are an 'aspect' of brain processes, in what sense of the word 'aspect'? I believe that if we are to retain the term 'mental events' we may do so only if we use it as a term completely interchangeable with 'brain processes'.
As a coda to the above considerations, Anderson's (1962) suggestion that 'mind is feeling' rather than brain processes may be treated. Do we really think of emotions when we think of mental events? No. We think of emotions as somatic events. They are perceived in the same way as we perceive a blue object. The only difference is that the impulse comes from different receptors (visceral) and projects in a different part of the cortex. An emotion is a visceral conditioned response to stimuli perceived externally and then a conditioned stimulus for further motor conditioned responses (e.g. flight). The temporal order here is not important. As in the James-Lange theory, the motor action may also come as a direct conditioned response to external stimuli, with the emotional response subsequent.
REFERENCES
ANDERSON, J. (1962) Studies in empirical philosophy. Sydney: Angus & Robertson.
BURT, C. (1968) Brain and consciousness. British J. Psychology, 59(1), 55-69.
HEBB, D.O. (1949) The organization of behavior. N.Y.: Wiley.
LYNN, R. (1966) Attention, Arousal and the Orientation Reaction. London: Pergamon
PAVLOV, I. P. (1932) Selected works. Moscow: Foreign Languages Publishing House.
PLACE, U.T. (1969) Burt on brain and consciousness. Bulletin of the British Psychological Society, 22, 285-292.
FINIS
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