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II Willi!" >K (IF PHYSIOLOGY 



XF.l'ROPHYSIOLOGY III 



As we have already pointed out, the same coal 

 m.i\ be reached by different behavioral means at 

 different times. This variability in goal-directed be- 

 havior is ureatlv increased l>y learning new instru- 

 mentalities to attain goals and in learning new goals. 

 Thus, a rat may learn to escape or avoid electric 

 shock by depressing a lever, turning a wheel, standing 

 on its hind legs, leaping over a hurdle, running 

 through a white rather than a black door (146). Or 

 it may be taught one arbitrary response to obtain 

 food and another to obtain water (88), showing not 

 only specific instrumentalities appropriate to each 

 motivation but also a precise discrimination of its 

 own motivational states. In addition to such selective 

 learning of new instrumentalities, the animal, of 

 course, may also learn new goals, thereby expressing 

 its motivation in new ways, not involving consumma- 

 tory behavior or other natural patterns of expression. 



Satiation 



Satiation or satiety refers to the reduction ol moti- 

 vated behavior following the achievement of a goal. 

 Subjectively, this is relief from pain, satisfaction or 

 pleasure; or it may be loss of interest or indifference. 

 Operationally, it is the reduction of the organism's 

 drive, its general activity and restlessness, and its 

 specific goal-directed behavior. Since an animal is 

 typically under the influence of many motivations at 

 once, reduction in the expression ol one motivation 

 ma) be due, in part, to the interference resulting from 

 the expression of other motivations. The thirsty ani- 

 mal, for example, drinks steadily until it is presumabl) 

 tun ed to rest in response to fatigue; after a brief rest, 

 il returns to drink some more, and then rests an, tin. 



\ the tendency to drink reduces even more, the ani- 

 mal ma\ turn to food and eat instead of drink. Then 

 it may drink In iefl\ again, then groom itself. Eventu- 

 ally, ii ma\ sleep, presumabl) a response to still 

 another motivation (152). So satiation must be 

 thought of not only in term- ol direct reduction of 

 drive and goal-oriented response, but also in terms of 

 ill- 1 ompetition oi motives. 

 Physiologically, we are no) sure whal satiation is. 



\ ugge ted earlier, it can be thought of most simpl) 

 .1- .in mi re.ise in the activit) oi inhibitory mechanisms 

 in the diencephalon which lead direcd) or indirecd) 

 to a redui nun in the activity of the central excitatory 

 11 hi nanism 01 1 1 ounteraction <>l iis effects. Presum- 

 ably, correction of .1 deficit in the internal environ- 

 ment ma) lead in atiation; some evidence suggests 



that menu the execution ol a pattern ol motivated 



behavior feeds back .stimulation which contributes to 

 satiation, fatigue and sensory adaptation may also 

 enter as factors, and learning may possibly enter. The 

 problem of what factors contribute to satiation is 

 something on which we have some evidence, but it is 

 still a major experimental question and we have yet 

 to work out the details of the ncurophysiological 

 mechanism involved. 



Motivated Behavior 



In terms of this analysis, then, motivated behavior 

 includes three major behavioral processes: the arousal 

 of drive, goal-directed activity and satiation. Physio- 

 logically, these are the problems of: a) activation of an 

 excitatory mechanism by internal states, and learned 

 and unlearned sensory influences; b) the basis of the 

 change in sensitivity and reactivity of the organism 

 to patterns of sensory stimuli, and the mechanisms 

 responsible for the organization and facilitation of the 

 patterns of response involved in the specific execution 

 of the motivated behavior; and c) the activation of an 

 inhibitory mechanism by internal states, and learned 

 and unlearned sensory influences. 



Behaviorally, the experimental study of motivation 

 requires: a) the measurement of drive or the intensity 

 of motivated behavior; 6) the analysis and measure- 

 ment of goals, their effectiveness and their modifi- 

 ability through learning, and the measurement of 

 selection, choice or preference in the execution of 

 specific goal-oriented behavior and the modification 

 of these specific responses by learning; and < I the 

 specification of the conditions under which satiation 

 will occur and the measurement of its magnitude, 

 especially taking cognizance of the competition among 

 motives. Some of these problems will be taken up in 

 the next section, then we will <_;o on to address the 

 physiological problems. 



HI II \V1( >R.M Ml \sl RI-.S ( il M< il IV \ I K1X 



As you can see from the Complexity of main of the 

 concepts arising in the anal) sis of motivated behavior, 

 it is extremel) important to anchor them experi- 

 mentally. b\ use of operational definitions. Io a large 

 degree, this is the problem of the experimental meas- 

 urement of behavior Therefore, at this point, it will 

 be helpful to review the methods that have been used 

 in specif) motivated behavior and to measure its 



various |,n etS 



