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HANDBOOK OF I'HYSIOLOGY 



Ml Rl IPHYSIOI OtJY III 



literature and science tend to agree that periods ol 

 reflection, tranquility and even of solitude may favor 

 the emergence of signifu anl ideas. 



/ k Vea ■/'. and Sufficient 



In the above paradigm of thinking behavior we 

 have attempted to reduce the manifest complexity to 

 iis essentials. Is something still lacking? Do the neural 

 mechanisms provided for in our model offer sufficient 

 degrees of freedom for the great range of adaptive 

 behavior characteristic of Homo sapiens? In thinking 

 about the model the writer turns to the analogy of a 

 television receiver. Obviously one could specify the 

 rather complex circuitry of such a machine, detect 

 operationally that it is turned on or 'aroused,' check 

 electronically that information is coursing through all 

 parts of the primary circuits, and still not have a 

 picture on the screen. A "focusing circuit' could be de- 

 fective or absent. 



Do we need to postulate something analogous to a 

 focusing circuit as the "little man' who directs attention 

 or conscious awareness first this way, then that? There 

 is experimental evidence which suggests that we do. 

 Kliiver (31), for example, studied eidetic imagery in 

 children and adults. Such imagery is characterized by 

 almost photographic fidelity in the degree of detail 

 which is present in the recalled memory trace. Shown 

 a black ,md white picture of numerous objects, the 

 eideticer can, following brie! delay, project onto a 

 gray background a remarkably detailed copy of the 

 picture any parts of which can be enhanced in v iv -ill- 

 ness "at will' with blurring of the remainder. 



I here is as yet no clue as to the special neuro- 

 physiology of differential attention (focusing). It is 

 possible that the heightened consciousness of patterns 

 nl excitation thus implied is the epiphenomen.il ac- 

 companiment of differential attention. The possible 

 involvement of the amygdala complex in attention has 

 been suggested by Lesse (39) and Gloor (Chaptei 

 I A 111 ol this Handbook). 



Conversely, it may lie that the neural elements 

 which mediate the highest levels of correlation and 

 integration .ire characterized by relatively high ex- 

 1 itatory thresholds. Thus the closure effect may require 

 the patterned summation of relatively large segments 



ot 1 lie neural pool to bring oil' high levels of conscious- 

 ness 01 attention (!'>, 16, . , 



\l ■'■ oc ■ St idying I ■ 

 I he introspective method for the study of thinking 



has been vv idelv employed in the past. However, the 



dependency of this method upon the language process, 



which is slow, cumbersome and quite loosely coupled 

 to the internal prores.es of thinking, has limited the 

 fruitfulness of this approach. To a considerable extent 

 these limitations are shared by the projective tech- 

 niques as applied to thinking behavior. 



In addition to the well-known problem-solving 

 studies of Maier (40), experimental studies of thinking 

 behavior in man have been carried out by Hull (24), 

 Smoke (52), Heidbreder (19), Halstead (14, 1 5 . 

 Goldstein (1:5), Hanfmann & Kasanin (17), and 

 others. The general technique here has invoked the 

 presentation of a series of stimulus objects with one or 

 more properties in common but differing in many 

 others. The task of the subject is to derive and general- 

 ize the basis of essential similarity in the presence of 

 dissimilarities, and vice versa. 



The electroencephalogram (EEG) has thus far 

 proved of little use as a tool for studying the thinking 

 process (1, 18). There are, however, developments 

 under way in this area which may have considerable 

 significance. Brazier & Casby (5, 6) and Barlow & 

 Brazier (2) have applied correlation techniques di- 

 rectly to EEG recording. Autocorrelations and cross- 

 correlations have been obtained from homologous and 

 nonhomologous brain areas of normal subjects, from 



in. 2. Hypothetical correlation between nonspecific ef- 

 ferent outflows to Hi'- peripherj [Y) and nonspecific afferent 

 (proprioceptive) feedbacks to tin- neural pool (AT) with facili 

 tating effect on thinking behavior. (See discussion of the 

 sec ond .ind third si.iycs of thinking lic-h.iv ior in text I V specific 

 elements; A, nonspecific elements; E, efferent outflows; and 

 / . efferent outflows phenomenally coupled to A'. 



