Neuron connections will also, and inevitably, spread activation to areas where all the other data about the person is managed – their place in my life, the world and so on. And so on. And so on. (And see a discussion of pattern associators in the notes to chapter two.)
Supposing, then, that I know that my Danish wife and our son are both home and a voice calls to me. My voice recognition modules burst into action. They detect a characteristic pattern of higher frequencies and Danish intonations. These patterns will tend to excite the distant but related ‘wife identification’ modules but tend also to inhibit those for ‘son recognition’. I will be some way towards the correct identification of my wife’s call, and my wife herself as a result, even before my voice bank has fully analysed the sound. The excitation of ‘wife ID’ modules will tend to excite even very distantly related modules, for example those related to shopping – we are to do the weekly shopping today – and these modules will tend to excite those in which (I hope) I presently hold the information as to what I think we need to buy, what I need to wear and where the keys are. All this (it is time to go) is tending to inhibit activity in those modules presently engaged in locating and organising ideas about cognition, and dressing them in respectable language.
This has been our first glimpse of the absolutely fundamental mental process of spreading activation whereby any brain activity tends to reverberate around all sorts of perhaps only vaguely related subject areas in the mind. We can begin to see how this process, especially if on/off and dimmer switching possibilities are built into the system, enables decisions to be reached very fast and their implications spread and considered very rapidly. These decisions may involve many different aspects of the same issue simultaneously (remember our tennis player). Spreading activation not only enables rapid decision-making but also enriches information by involving all the different facets of it which we have in our heads. This combining and re-combining of information within the mind is association. It is thought that about 95% of the activity in the cerebral cortex at any time is pure association within it, only about 5% being either the intake of new information to the brain or the delivery of instructions from it. This association can be thought of as what, today, would be called ‘information processing’. (Though see a fascinating chapter by Frank Smith in Olson et al (1985) debating whether what we have in our heads should properly be called ‘information’ at all. You may also wish to read about ecological psychology. This now-you-see-it-now-you-don’t approach begins with Gibson (1986) and is briefly discussed in my notes to this chapter).
We have taken a preliminary look at the brain – its structures and its processes. What we have seen is an organ of colossal potential in which specific tasks are managed in specific areas but in which everywhere informs and is informed by everywhere else. We saw that we have two distinct brains but that these communicate totally and continuously across the corpus callosum. We saw the limbic system curled up at the centre of the brain and we saw that these structures also communicate intimately and continually with the ‘higher’ cortex. The limbic system mediates, monitors and to some extent at least controls some of the activities of the cortex which we used to regard as purely, indeed loftily, intellectual.
It’s not quite this simple and the cortex is neither as distinct nor as authoritative as we would like to believe. Nor, of course, is our consciousness. The limbic system also mediates general states, such as emotional status and mental arousal, and is involved in issues such as memory and recall. We dismissed phrenology and crossed laterality but embraced humility and scepticism, and we considered two very basic brain processes, association and spreading activation. We observed, as a result, that the brain is a flexible, omnivorous learner with a capacity which we may consider to be limitless for practical purposes. Having laid these foundations we are now ready to consider the brain’s behaviours; how it may manage language in its various forms and literacy in particular.