THE LEVELS OF BEHAVIOUR 153 



Reflection on one's own behaviour and observation of that of 

 animals that one knows well will amply demonstrate this. 



54^. The Establishment of a Motor Habit. Such actions 

 as these : the spinning of a web by a spider ; the building of a 

 nest by a bird ; swimming by a boy ; the rapid building of a 

 wall by a bricklayer, etc., all involve the establishment of motor- 

 habits. They are series of bodily actions that may be performed 

 efficiently and automatically. Each involves trains of accurately 

 adjusted, co-ordinated and chained reflexes such that the com- 

 pletion of one series of acts is seen, felt, etc., and is the stimulus 

 that initiates the succeeding acts (just as in organic functioning 

 the contraction of one segment of the alimentary canal is the 

 stimulus for the contraction of the succeeding segment, or 

 peristalsis). The physiological basis of this motor-habit estab- 

 lishment is the laying down of a neurone- pattern. 



Neurone-patterns. If we " blink " with the eyes there is some 

 visual stimulus, with noxious meaning, that affects the retinal 

 receptors. This stimulates the optic nerves, which are con- 

 nected, via synapses, with fibres that stimulate the synapses in 

 the centres, or nuclei, of the motor nerves of the eyelids. These 

 latter muscles are finally stimulated and we " blink." Thus 

 the reflex uses, as a mechanism, a particular chain of neurones, 

 among very many other chains that are all possible ones. The 

 chain involved in blinking-behaviour is a neurone-pattern. How 

 neurone-patterns are set up we can only " explain " by the 

 random conception. Many possible trains of neuro-muscular 

 activity may follow a stimulus (because of the exceeding com- 

 plexity of the synaptic nervous system.) In the initiation of a 

 motor habit many such trains are certainly " tried " and one 

 proves to be successful — that is, is instrumental in behaviour 

 that satisfies a need, averts a danger and so on. This train is 

 afterwards adopted by the animal, without initiatory trials, 

 when a stimulus having the original meaning is received. But 

 the essence of the explanation is this — how does the successful 

 response become adopted, or selected, from among all the 

 possible ones } The answer is impossible on ordinary physical 

 grounds. The adoption of the neurone-pattern means selection — 

 that is, something opposed to randomness and psychical in 

 nature. Apart altogether from laboratory experiments intro- 

 spection with regard to our own behaviour and observation of 



