Story of Psychology - Morton Hunt [367]
On a larger scale, the connectionist model of information processing is in striking accord with other seminal findings of cognitive psychological research. Consider, for instance, what is now known about the semantic memory network in Figure 41. Each node in that network— “bird,” “canary,” and “sing,” for instance—corresponds to a connectionist module something like the entire array in the last diagram but perhaps consisting of thousands of units rather than eight.110 Imagine, if you can, enough such multithousand-unit modules to register all the knowledge stored in your mind, each with millions of connections to related modules, and… But the task is too great for imagination. The connectionist architecture of the mind is no more possible to visualize in its entirety than the structure of the universe; only theory and mathematical symbols can encompass it.
The connectionist model is strongly analogous to actual brain structure and function. The late Francis Crick, who shared a Nobel Prize for discovering the structure of DNA and then did neuroscience research at the Salk Institute, said that the concept of the brain as a complex hierarchy of largely parallel processors “is almost certainly along the right lines.”111 Paul Churchland and Patricia Churchland—each a philosopher of cognitive science—have said that the brain is indeed a parallel machine “in the sense that signals are processed in millions of different pathways simultaneously.” Each aggregation of neurons sends millions of signals to other aggregations and receives return signals from them that modify its output in one way or another. It is these recurrent patterns of connection that “make the brain a genuine dynamical system whose continuing behavior is both highly complex and to some degree independent of its peripheral stimuli.”112 Thus could Descartes, lying abed all morning, think about his own thoughts, as has many a psychologist since.
Possibly the most remarkable development of all is, as noted above, the change in the relationship between computer and mind. A generation ago, it seemed that the computer was the model by which the reasoning mind could be understood. Now the order has been reversed: The reasoning mind is the model by which a more intelligent computer can be built. Artificial intelligence researchers have been writing programs that simulate the parallel processing of small neural networks, their aim being to create AI programs that are more nearly intelligent than those based on serial processing, and to create programs that simulate hypothesized mental processes so that they can be tested on a computer.
A wonderful irony: The brain that makes mind possible turns out to be the best model for the machine that had been thought vastly superior to it, a model so complex and intricate that it is all the computer can do, for now, to replicate a few of its multitude of functions and make only symbolic simulations of a handful of others.
As David, the greatest of psalmists, sang twenty-five centuries before the cognitive revolution and the computer age, “I will praise thee; for I am fearfully and wonderfully made.”
And the Winner Is—
We have followed the revolutionary development of cognitive psychology and the later but equally revolutionary development of cognitive neuroscience, which currently coexist, overlapping and infiltrating each other. But will they continue to do so or is one likely to dominate and absorb the other, becoming the psychology of the future? The answer would seem to depend on which discipline offers the better scientific explanation of mental processes and behavior.
Cognitive psychology, as we have seen,