152 ANIMAL BEHAVIOUR 



town that is strange to him will at first find his way from one 

 point to another by trials, but very soon he will discover the 

 shortest route. Obviously dogs and carrier pigeons will do 

 much the same thing, and so on. 



'' Conditioned Reflexes " demonstrate experience as it affects 

 organic functioning and behaviour. A dog, for instance, is 

 given food at the same time, or slightly after a whistle, or some 

 other signal. The dog salivates while he eats the food. After 

 many repetitions of the signal and the feeding the dog will 

 salivate when the signal alone is made. This is a reflex to a 

 stimulus which did not of itself originally evoke response but 

 which acquired significance from its association with food — 

 that is, by the experience of the animal. Again, ordinary 

 observation will show the same result — the dog knows the dinner 

 bell. The normal dog, will, of course, salivate when shown 

 food and, after some training, when food is spoken about. But it 

 is easy to see that the normal unmutilated dog can be '' fooled " — 

 when his behaviour to a signal may change. The " conditioned " 

 reflex is said to be *' inhibited." 



The historical basis of acting. In all these cases of behaviour 

 that becomes more efficient by repetition there is a history of 

 events that were anticipatory to the " finished " behaviour. 

 Some satisfactory response to external conditions becomes 

 established in the behaviour of an animal. A stimulus is 

 received and then the animal responds by some train of actions 

 which we proceed to analyse. We see clearly in ordinary 

 behaviour that the activity cannot be simply a response in the 

 sense that a *' decerebrate frog " will (for instance) croak inevit- 

 ably when its body is stroked in a certain way : what we call 

 the stimulus in ordinary behaviour is far more complex than 

 this and it is not simply some physical events in the environ- 

 ment. Thus to a bilingual person a sentence in French is an 

 entirely different physical stimulus from one in German, but 

 the two sentences may evoke precisely the same behaviour. 

 When Mark Twain was learning German the word " damit " 

 satisfied a certain need, but when he came fully to understand 

 its meaning it, as a stimulus to behaviour, became *' conditioned " 

 and no longer led to the same response. A physical stimulus 

 acquires meaning when it has become associated in memory, or 

 in motor habit, with certain other stimuli and responses. 



