VI 



INSTINCT 8 1 



each several movement as a reflex, we should find at once 

 that it was a reflex in which the response instead of 

 varying uniformly with the stimulus, varied in accordance 

 with circumstances. The sight of the prey at a certain 

 distance, and with its back turned, induces stealthy 

 approach ; at close quarters a sudden leap. The turning 

 of the sandhopper's head sets in motion the responses. 

 This is a complex series involved in burrowing under the 

 sand. Everything varies according to the position and 

 movements of the animal pursued, that is to say, the 

 action is sensori-motor, and indeed there is a series of 

 sensori-motor acts adjusted from moment to moment, not 

 to a series of simple sense stimuli, but to the changing 

 phases of a complex situation. 



By the " situation " here is meant those objects and 

 changes in the immediate surroundings that have a bearing 

 on the attainment of a particular end, and operate on the 

 sense organs of an animal. The influence which we have 

 to ascribe to the situation implies the existence of an 

 abiding internal state of the organism which deals with it, 

 adjusting action to its changing phases in the way 

 described. Just as the reflex excitability is the correlative of 

 the sense-stimulus, so this relatively permanent state, which 

 dominates many reflexes, is the correlative of a combination 

 of circumstances, or a a situation." To mate and breed 

 the female dove requires not only the male but facilities 

 for nesting, courting, and generally a suitable environ- 

 ment " no one factor determines it." The transform- 

 ation of the dove's attitude is " determined by the entire 

 social situation." 1 It is this relatively permanent state, 



1 The Stimulation and the Inhibition of Ovulation in Birds and 

 Mammals, Wallace Craig, J.A.B. 1913, pp. 214-221. Conversely, when 

 the brooding instinct is once aroused the appropriate stimuli act almost 

 as reflexes. " Contact with the nest under appropriate conditions excites 

 a powerful suggestion or an almost hypnotic influence upon the bird, 

 which somehow involves the ovaries. This attitude leads her to work 

 further upon the nest. Such work causes the stimulus from the nest to be 

 repeated. Thus the circular activity goes on and on.' 3 Of the influence 

 of the male on laying, the writer said earlier that it was a psychological 

 influence. In this passage he withdraws the term in ' favour of the 

 reflex, but he adds : " It is not a simple reflex. It is a reflex which is set 

 working, not by any one sense stimulus, but by the total situation, 

 including both the totality of present sense stimuli and also memory 

 factors" (p. 217). 



