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HANDBOOK OF PHYSIOLOGY 



\l I KOPHYSIOLOGY III 



Neural and Humoral Forms oj Information 



The mind stuff or information which requires to 

 be correlated and integrated by the brain consists of 



a) specific sensory input from the classical receptors, 



b) specific and nonspecific afferent feedbacks, c) 

 specific and nonspecific efferent outflows, d) specific 

 and nonspecific memory traces, and e) 'noise.' These 

 are the ingredients of organized behavior whether the 

 prevailing set of the system be predominantly for 

 perception, learning, emotion or thinking. It is not 

 feasible to elaborate upon each of them here, but we 

 shall return to a consideration of their formal proper- 

 ties as we attempt to relate them to the warp and 

 woof of neural structure. It is reasonable to suppose 

 that neurochemistry is intimately invoked in each 

 of the above mechanisms, but the critical correla- 

 tion-, and integrations in this area must await future 

 developments (28). 



Nature oj Explanation 



When does thinking begin and when can it be 

 said to reach an ending? In other words, is thinking 

 comprised of a train of events characterized by a 

 distinct "on" and a distinct "off" effect: 1 In general, 

 the answer to both parts of ihis question is yes. Think- 

 ing begins with the conscious awareness of a problem. 

 It terminates for the particular problem by the 

 emergence of a satisfactory solution or explanation. 

 Whitehead has defined an explanation as "that stage 

 where curiosin < eases." While reduction or cessation 

 of curiosity is symptomatically related to the end- 

 stage of thinking for the individual, it is doubtful 

 that this is a reliable index. It may be necessary 

 without being sufficient. 



Canonical Form oj Explanation 



The 'off effect for thinking occurs when the 

 canonical form of classification of the critical events 

 of the particular problem is achieved. The canonical 

 form of thought is the paradigm of all organized 

 knowledge. It is characterized l>\ a) reduction or 

 cessation oi specific curiosity, and b) maximal security 

 .1- to adequacy of solution or explanation. A problem 

 ma) be said to be solved when its critical events can 

 be ordered as to homology, analog) and an emergent. 

 Hiese are the cardinal categories of science. They 

 serve equally the indiv idual and the group for testing 

 the creative or emergent against the background of 

 in/id know ledge 



MODEL FOR THINKING ABOUT THINKING 



At the outset of our discussion a five-stage model 

 of thinking behavior was set forth. In adopting it the 

 writer has been influenced by his colleagues, by other 

 investigators and by thoughtful and stimulating dis- 

 cussions of these matters with several students who 

 have participated over the years in his graduate 

 seminar on higher brain functions. 



Stages of Thinking Behavior 



PERIOD OF PRELIMINARY EXPLORATION. As may be 



seen in figure 1, thinking begins with a presenting 

 stimulus situation which is coercive (curiositv 

 arousing, attention demanding) for exploration. It 

 begins as specific sensory input from one or more of 

 the classical receptors (eye, ear, etc.). This input is 

 organized ah initio into figure-ground relationship 

 (Koehler, Lashley) or "primitive unity 1 (Hebb) 

 The primitive unity of a figure is segregated from the 

 ground which, in turn, depends on the prevailing 

 pattern of excitation and the inherited characteristics 

 of the nervous system. The unity is relatively inde- 

 pendent of past experience. The figure-ground con- 

 figuration is scanned rapidly (the A Factor of 

 Halstead) for homologous or analogous match with 

 specific memory traces of past experience. If a prompt 



no 1. A figure-ground configuration illustrating tl»' 

 sequence ol prototype questions arising in perception and 

 thinking, "What is this?"; "What could it be?"; "What must 

 it be?" 



