Bridgeman's article is important but is only a single step in the right direction. It must also be accepted that the complete psychology of an individual could only portray a shadow of their full personality. It is the reportability of our plans that makes links between individuals possible, and that it is the consequences and characteristics of these links that complete our personalities.
2. Yerkes (1945) said "One chimpanzee is not a chimpanzee at all," echoing Donne's "No man is an island, entire of itself." And it is true: You simply cannot take a single, isolated, brain, whether it be of man or chimpanzee, and talk usefully about a high-level phenomenon such as consciousness. You can talk about the control of muscular contraction, the responses of retinal ganglion cells, and many other semi-autonomous, low-level, processes, but it is absurd even to think about consciousness as a phenomenon in a single isolated brain, because its biological role is to facilitate social interactions (Barlow 1987).
3. Resistance to the idea that it takes two (or more) to be conscious stems from the firm illusion that our own individual, unaided, brain provides an example to the contrary. But that is a gross conceit: if you have been reasonably lucky your brain will have had many years of care and affection lavished on it, not to mention many thousands of educational dollars. You have a right to regard your brain as your own, but not to deny the influence of these years and dollars. Since your own brain has been comprehensively worked over in this way it is an example of a brain moulded by other brains, and its properties, consciousness among them, cannot possibly be regarded as attributes of an isolated, single brain. You would not think of an earthenware vase as an attribute of clay alone, for most of its qualities result from the potter's hand; likewise, each of our brains includes the handiwork of many other brains.
4. William James (1890), who also thought that consciousness was much concerned with an individual's plans, was worried that mechanistic explanations of brain function might leave nothing for conscious thought to control or explain, even in the simple behaviour of seeking what gives conscious pleasure and avoiding what causes conscious pain. But why worry if simple hedonistic behaviour can be explained without taking consciousness into account? The fact that we can report our plans and associated subjective experiences makes all the difference to our social behaviour, for this is how we establish links with one another, with our past, and with our future. That is surely a grand enough role for consciousness.
Bridgeman, Bruce (1992) On the Evolution of Consciousness and Language. PSYCOLOQUY 3 (15) consciousness.1
Yerkes, R M (1945) Chimpanzees, a laboratory colony. New Haven: Yale University Press
Donne, John (1573-1631) A Valediction Forbidding Mourning.
Barlow, H.B. (1987). The biological role of consciousness. In: C. Blakemore & S. Greenfield (Eds.), Mindwaves. Oxford: Basil Blackwell.
James, W. (1890). Chapter 5 Book 1 of The Principles of Psychology Boston: Henry Holt and Co; (also Dover Publications Inc 1950).