CHAPTER 18 



Interaction between Adaptations 



18/1. At this stage it is convenient to consider in more detail 

 the question of ' localisation ' in a multistable system : how will 

 the pattern of activity be distributed within it ? In treating the 

 brain as a multistable system we followed the incoming sensory 

 stimuli through the sense-organs to the sensory cortex (S. 15/5 

 and 15/6) ; we have now to consider what happens in the areas of 

 4 association ', not of course in detail but sufficiently to develop a 

 clear picture of what we would expect to see there. 



Some functions in the cortex are, of course, unquestionably 

 localised : the reception of retinal stimuli at the area striata for 

 instance. With such I shall not be concerned. I shall consider 

 only the localisation of learned reactions, especially of those to 

 situations, such as puzzle-boxes containing food, for which the 

 organism has no detailed inborn preparation. In such a case the 

 simplest hypothesis, the one to be tried first, is that the dispersion 

 occurs at random. By this I mean that at each elementary point, 

 at each synapse perhaps, the functional details are determined by 

 factors of only local significance and action : whether two pieds 

 terminaux make contact or three, whether the nucleus happens to 

 be on this side of the cell or that, whether five dendrons converge 

 or seven (I use these examples only as illustrations of my mean- 

 ing). Such details have been determined by primary genetic 

 factors modified by merely local incidents in embryological 

 development and perhaps by local incidents in past learning. 



But though the local details were once decided by some trifling 

 local event, I assume that they persist with some tenacity; for 

 learned behaviour can, in the absence of disruptive factors, per- 

 sist for many years. I will quote a single example. By differ- 

 ential reinforcement with food, Skinner trained twenty young 

 pigeons to peck at a translucent key when it was illuminated 

 with a complex visual pattern. They were then transferred to the 



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