DRIVE AND MOTIVATION 



'5°9 



it is measured, whether it is the amount of general 

 activity an animal shows, the amount of ingestion, the 

 amount of work done to overcome a barrier to a goal, 

 or the frequency, speed or magnitude of a response 

 instrumental in reaching or avoiding a goal. Although 

 drive has been used in the past to refer to animistic 

 forces which propel or energize the motivated animal, 

 its value in modern usage is that it can be specified 

 quantitatively and operationally by a variety of ex- 

 perimental measures which we shall discuss below. It 

 should also be mentioned at this point that drives may 

 be learned in the sense that previously neutral stimuli 

 may elicit an increase in any of the measures of drive 

 after appropriate experience. Thus, a rat will learn 

 to work hard to escape a weak visual or auditory 

 stimulus that has previously been followed by electric 

 shock (97). Or a chimpanzee will work for a poker 

 chip that can later be used to obtain food (170). From 

 a physiological point of view, drive, whatever its 

 origin, must be equivalent to the degree of activation 

 or arousal of the excitatory neural mechanism 

 operating in motivation. While there is some evidence 

 supporting this assumption, much experimental work 

 is needed before the mechanism of drive can be speci- 

 fied in any detail. 



Goal 



The goal of motivated behavior is not always easy to 



specify. In a simple case, it may be some specific ob- 

 ject which the organism approaches or avoids selec- 

 tively and acts upon with a particular pattern of be- 

 havior, like a mate or a noxious stimulus. In some 

 cases, however, there may be no specific identifiable 

 object as in sleep, a burst of running activity or ex- 

 ploration; and even where there is a goal object, part 

 of the goal, at least, may be simply the stimulation 

 arising from the execution of a pattern of response. 

 Experimentally, a goal is identified when, following 

 attainment of the goal object or execution of the goal 

 response, there is a reduction of drive and eventually 

 satiation. In addition, where specific goal objects are 

 involved, the goal is also indicated by the organism's 

 selective orientation to it, cither approach or avoid- 

 ance. 



We will discuss both satiation and goal-directed 

 behavior in a moment. At this point, it is worth noting 

 that once a goal is reached or an animal has had pre- 

 vious experience with it, it may function to increase 

 drive, depending upon the nature and pattern of stim- 

 ulation the goal provides. For example, a 10 per cent 

 glucose solution will elicit more consummatory be- 



havior and more work, even when ingestion is rela- 

 tively negligible, than a 5 per cent glucose solution 

 (64, 95). Behaviorally, then, we may speak of the 

 'incentive-value' of the goal; physiologically, this is 

 presumably correlated with its relative contribution 

 to the arousal of the excitatory neural mechanism in- 

 volved in motivation. 



A suitable goal may be used to promote learning or 

 maintain performance in a motivated animal, as in 

 the case of the animal learning to run a maze to reach 

 food. In this instance, we refer to the goal as a 're- 

 ward.' Rewards and 'punishment' in the case of 

 noxious stimuli are also called positive and negative 

 'reinforcements' to signify their effects in strengthen- 

 ing learning and performance when appropriately ap- 

 plied in an experiment. Furthermore, as you might 

 expect, goals may be learned, as in the case where the 

 poker chip becomes (he goal of the chimpanzee's 

 efforts. Then we speak of acquired goals' and second- 

 ary rewards and secondary reinforcement in contra- 

 distinction to primary rewards and primary rein- 

 forccmenl which require little or no learning to be 

 effective. We know relatively little about the physiol- 

 ogy ol learning but, in eases like these, presumably the 

 central neural mechanism in motivation plays an 

 important role. Later in this chapter, we shall dis- 

 cuss briefly some direct experimental approaches to 

 the physiology of reinforcement. 



Goal-Directed Be ha mot 



This is the specific pattern of behavior, associated 

 with .1 particular kind of motivation and elicited by 

 specific environmental stimuli, from an objective 

 point of view, this is the appetitive behavior of the 

 students of instinct; the appetite of the physiologist 

 and psychologist; the pleasure seeking and pain 

 avoidance of the philosopher and the psychologist, 

 the preference, choice, the approach, avoidance, the 

 selective behavior of the experimental psychologist. 



Orientation to a goal involves two major aspects. 

 One is the selective perception of the goal. In the 

 motivated state, the organism is particularly sensitive 

 to certain facets of the environment, as in the response 

 of the maternal organism to its young or the male rat 

 to the female in heat. The other is that, in the moti- 

 \ .1 ted state, certain response patterns are facilitated, 

 in the extreme case of very strong motivation, to the 

 point where the goal-directed response may be 

 emitted 'spontaneously' or at least upon minimal 

 stimulation, the so-called "vacuum-reactions' of 

 Tinbergen and Lorenz. 



