CHAPTER V 

 BIOPSYCHOLOGICAL 



ANIMAL BEHAVIOUR. — In the strict sense behaviour implies a 

 chain of actions adjusted towards a particular result; thus a single 

 reaction of an Amoeba is hardly worthy of the name, whereas the 

 pursuit of one Amoeba by another must be so regarded. Behaviour 

 is a purposive concatenation of diverse activities. A single reflex 

 action, such as drawing our finger away from a hot coal, is hardly 

 at the level of behaviour, being no more than one process, soon over 

 and done with. Yet reflexes are often linked in a chain, and the 

 physiological side of instinctive behaviour may be regarded as a 

 long chain of linked reflexes. Thus it seems impossible to draw a 

 dividing line, and in this chapter we are using the word behaviour 

 in a wide sense. 



If we were taking a survey of animal behaviour from the purely 

 physiological side, we should naturally begin with relatively simple 

 responses to stimuli, such as reflex actions, and from these we should 

 work gradually upwards to activities which require psychological 

 terms for their description. 



But here it is useful to reverse the order of treatment and begin 

 with the highest animals and their most striking doings. For we are 

 passing in this chapter to the definitely psychological level; and 

 while the mental or psychical factor is insistently clear among birds 

 and mammals, it is often dim at lower levels, until among the 

 simplest it is only hinted at ; and the question rises whether it may 

 not be usefully ignored. It should be noted, however, in regard to 

 cases like tropisms, where the simple behaviour seems to be ade- 

 quately describable in neuromuscular terms, it does not follow that 

 the origin of the enregistered predispositions can be thus accounted 

 for. Moreover, as we shall afterwards see, the psychic life of an 

 animal is not restricted to the mental processes, such as image- 

 forming and memory and sometimes inference, that lie immediately 

 behind or form the subjective aspect of the behaviour. There is the 

 often intense emotional activity of the creature and the tumult of 

 desire. Even when an apsychic description can be given of an isolated 

 chain of acts, this may be entirely inadequate for the life as a whole. 



(I) RATIONAL CONDUCT.— In the more distinctively human 

 activities of a man there is rational conduct, which cannot be 

 described except in terms of conceptual inference. There is working 

 with general ideas or concepts, such as those utilised in building a 

 house ; or there is a control of the main tenor of life in reference to 

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