Fitting the body to the mind: cognitive tasks and somatic tools.

The first cognitive revolution, initiated by Bruner (1976) and Miller (1960), was directed against the behaviorist conception of the task of psychology. Bruner showed that many psychological phenomena, such as the perception of shape and the recognition of words, could not be explained without taking into account what appeared to be a body of knowledge that was not consciously referred to or deliberately accessed in making a conscious judgment or having a conscious experience. At that stage, the strategy of the cognitivists was to assume the existence of unconscious mental states and processes, an assumption still unquestioned by the advocates of "cognitive science." Furthermore, these states and processes were assumed to exist only in individual human beings.

The second cognitive revolution began with a rejection of psychological individualism and an emphasis on the interactions between persons as both the origin of cognitive capacities and as the site of many cognitive processes. In conversation and other symbolic interactions between persons, cognitive acts are performed publicly and collectively. Some cognitive phenomena only exist as properties of or structures in conversations (e.g., many cases of decision making). This emphasis led toward the developmental psychology of Vygotsky (1962) and a general anti-Cartesianism that was close to some of the insights of Wittgenstein's (1953) later philosophy, which has been influential in drawing attention to the dominant role of ordinary language as the main instrument of cognition. According to Vygotsky, the mind of an infant is created in the course of interpersonal interactions in which a symbiotic relation exists between mother and child. The mother completes what she takes to be the cognitive and intentional actions of the child, and the child imitates the mother's contributions. So many cognitive processes had their primary being in public collective interactions and only later were privatized and individualized.

At the same time as these developments were occurring, spurred in some measure by Bruner's (1976) own advocacy of attention to narratives in trying to understand the psychology of complex interactions, there has been great activity in the neurosciences. What role does the brain have in a psychology oriented to the intentional and normative interactions of which conversation is a major example? This question has wider implications because the answer that is given in this context may have consequences for the interpretation of the other area of great activity in contemporary psychology, namely artificial intelligence. I believe that the answer proposed in this article to the question posed in terms of cognition is also an answer to the question of the best interpretation of cognitive science as an offshoot of the program of artificial intelligence.

TRADITIONAL SOMATOPSYCHIC KNOWLEDGE AND SOME NEW DISCOVERIES

One can hardly imagine a time when it was not evident to even the Neanderthals that striking someone on the head deprived him (or sometimes her) of most cognitive and motor capacities. Because the brain is in the head, its role in the display of such capacities should have been obvious. Other correlations were evident too, such as the agitation of the heart when in an emotional state. The liver has also been implicated as the bodily site of melancholy and other depressions, although the experiential correlations are less immediately obvious.

But almost every day now there is additional weight being added to the correlation of brain processes and cognitive, social, and motor capacities. These reports refer to two rather different kinds of cases. There are correlations between genetic abnormalities and deficits in cognitive and social performance, the mediating structures in the central nervous system (CNS) being assumed, and there are demonstrations by positron emission tomography (PET) scans and magnetic resonance of the differential uptake of glucose in different parts of the brain, activated for different tasks. The older material, derived from studying which cognitive and motor processes were absent when certain kinds of brain damage occurred, was virtually useless because there was no way of knowing where in the chain of subprocesses the missing structure should fit. It might have been the site of the brain process actually involved in the cognitive task or merely the nearer of auxiliary or preliminary phases.

BRAIN ACTIVITY AND COGNITIVE PERFORMANCE

There are several different modes of correlation between cognitive activities and brain processes.

Positive Correlations

Example 1: "Both accurately and falsely remembered words stimulated cell activity - shown on PET scans as increased blood flow - in a part of the brain that has been linked to memory of information and events. Only accurate memories, however, sparked a simultaneous burst of activity in a brain region implicated in the retention of information about sounds and speech" (Bower, 1996).

Example 2: "Tiny electrical signals in the brain can be detected . . . if the volunteers move their fingers but also if they merely think of moving their fingers" (Stephen Roberts, reported in the Times, 11 September 1996).

Example 3: It has recently been shown in Oxford that the outer cortex of clever people is more alkaline than for those of lesser intellectual endowments.

Anomalous Correlations

Example 1: Men and women perform equally well at reading, as judged by ordinary standards of correctness. However, although PET scans show that in the brain, a small part of Wernicke's area is activated when men read, a broad band of cells across both hemispheres is active when women read.

Example 2: Some people diagnosed as having schizophrenia(1) benefit from chlorpromazine, others from lithium carbonate, and yet others are not helped by any psychoactive drug.

In these cases, the performance criteria do not pick out the same brain structure and activity in everyone capable of the activity.

Genetic Deficits

Example: The most surprising finding to appear recently concerns the fosB gene in mice. Greenberg and Brown (1996) showed that "both mother and father [mice] lacking the fosB-gene failed to make any attempt to nurture their young." At least we know now why there are no ordinary mice lacking that gene.

In each of these cases, the relevance of the neurological process is determined by criteria that identify the cognitive process …