1334 



HANDBOOK OF PH'S'SIOLOG'i' 



NEUROPHVSIOLOGV II 



24 



O 



-NORMALS 

 TEMPORALS 

 FRONTALS 



2 3 4 5 6 7 8 9 10 II 12 



no. lo. Graph of the average total number of trials taken 

 in the multiple object experiment by each of the groups 

 (Control = Normal; Posterior Intrinsic Lesion = Temporal; Frontal 

 Intrinsic Lesion = /'Von/n/) to reach, in each of the situations, a 

 criterion of performance of five consecutive correct responses. 

 A correct response occurred when tlie monkey moved the 

 object under which a peanut had been placed for that trial. 

 In a succession of trials, the peanut remained under one of 

 the objects until criterion performance was reached. Then 

 the peanut was shifted to one of the other objects in the situa- 

 tion and the trials resumed j this procedure was repeated until 

 each of the objects in each of the situations had been the correct 

 one. (See also the legends to figs. 4, 5, and 6.) 



■response" are also often confounded. As used in this 

 presentation 'response' denotes any dependent vari- 

 able whicli is selected as representative of an action, a 

 repertoire of responses which can be shown to be 

 systematically related. Movements of smooth muscle 

 and endocrine events comprise the eflfector com- 

 ponents of action; those components that modify re- 

 ceptor activity (i.e. the stimulus components) are 

 referred to as the 'outcome' of actions. Actions are 

 specified either ijy direct observations of the outcomes 

 of muscular or endocrine events (e.g. the changes in 

 the activity of afiferents from muscle spindles) or in- 

 directly from some behavioral response (e.g. the 

 record of depressions of a lever) made by the organ- 

 ism. The obviously circular relation between all of 

 these definitions is tolerable since each term is inde- 

 pendently as well as circularly definable, the environ- 

 inental terms by physical methods, the organismic 

 terms by biological methods. 



Behavior observed to be a function of systematic 

 variations of input is referred to as 'differentiative.' 

 Behavior observed to be a function of systematic 

 variations of outcome is referred to as "intentional.' 

 Problem solution in all instances involves both 

 differentiative and intentional behavior — however, 

 analysis is profitably focused on each in turn. 



between receptor and central mechanisms preclude 

 an understanding of the one without an appreciation 

 of the other. The importance of central regulation of 

 receptor events is attested by the findings of recent 

 physiological experiments which demonstrate mecha- 

 nisms that allow the regulation of afferent activity 

 through efTerents from the central nervous system: 

 the effect of electrical excitation of 7-eflrerents (one 

 third of the fibers in the ventral spinal root) in modify- 

 ing the activity of afiferents originating in muscle 

 spindles (21, 22, 67); the influence of excitation of 

 efferents in the otic system on afferent activity initiated 

 by auditory stimulation (36); and similar effects in the 

 optic (19, 46), somatic (47, 54) and olfactory (60) 

 systems. (These mechanisms are discussed in detail in 

 Chapter XXXI by Livingston.) 



'Stimuli' are thus conceived as centrally regulated 

 receptor events. To avoid confusion, the term 'input' 

 is reserved for those receptor events which can be 

 shown to be systematically related to an ensemble of 

 environmental events. Inputs are specified either by 

 direct observation of the effects of environmental 

 events on receptor events, or indirectly from such 

 effects on the behavioral responses of the organism. 



As with the term 'stimulus,' several uses of the term 



Some Experiments 



Returning to the multiple object experiment, 

 figure 10 graphs the average of the total number of 

 trials taken by each group of monkeys in each situ- 

 ation to reach the criterion of five consecutive errorless 

 responses. The peculiarities of the shape of the curve 

 representing the performance of the posteriorly oper- 

 ated animals have already been analyzed. The diffi- 

 culties in performance encountered by the frontally 

 operated group are more clearly demonstrated by 

 comparing the graph of the total number of trials 

 (fig. 10) with one that portrays performance following 

 completion of search, i.e. after the first response in 

 which the peanut is found (fig. 11). Note that the lag 

 shown by the frontally operated group in reducing 

 the number of trials taken to reach criterion (or the 

 number of repetitive errors made) occurs after the 

 peanut has been found (fig. 11). This group of monkeys 

 experiences difficulty in attaining on successive trials 

 the strategy of returning to the object under which on 

 the previous trial they have found the peanut. What- 

 ever may be the explanation of this diHiculty, a 

 precise description can be given: for the frontally oper- 

 ated group, 'finding the peanut' does not determine 



