70 BRAIN MECHANISMS AND LEARNING 



behaviour, but behaviour is adapted to certain environmental situations. There arc 

 two possibihties to explain such an adaptation: during evolution of a species, or bv 

 learning during the ontogeny of the individual. And wherever we find that such 

 highly adapted behaviour comes out in the animal in spite of complete lack of 

 previous knowledge of the specific stimulus situation to which its behaviour is 

 adapted, we speak of innate behaviour. If a male spider would need to learn its 

 complicated courtship postures it would get eaten by the female. When a male 

 mallard raised in isolation still shows its highly complicated courtship postures at 

 sexual maturity it demonstrates innate behaviour, in spite of the fact that the 

 animal might have learned something in addition to it. How our opponents argue 

 is demonstrated in Kuo's paper. He observed that in the chick embryo the head 

 rests on the heart and is lifted with every heartbeat. Thus nodding movements, a 

 part of the later pecking behaviour — get induced. Later nodding becomes inte- 

 grated with the previously independent swallowing movements into food-pecking 

 behaviour which every newly hatched chick shows. Our opponents express the 

 opinion that this behaviour was learned within the egg. (A detailed discussion is 

 given in my paper.) 



Hebb. No. 



EiBL-EiBESFELDT. Yes they do. Concluding from this and similar experiments 

 they say there is no innate motor pattern : everything is learned. 



Hebb. There is no support for that extreme view. My disagreement is with the 

 dichotomy you made earlier, between learned behaviour and instinctive behaviour. 



Thorpe. I agree with Dr Eibl-Eibesfeldt on this. Dr Lehrmann does not now 

 take this view, but he certainly did appear to do so at one time. I am glad that he 

 seems now to have come round to what I believe is the only reasonable position to 

 take. With birds you get the same sort of thing, in regard to this interlacement of 

 learned and innate behaviour patterns. It depends on the group as to how big these 

 innate chunks of behaviour are. In the mammal they are small and as you go down 

 the zoological scale they become larger, and they may be very large in insects or 

 spiders. One other point I would like to mention is that these experiments on 

 birds give clear evidence that the learning is too selective to be 'motivational' in 

 this sense. A theory which relies mainly on a supposed change in the general 

 motivational level would not carry us very far in explaining this type of learning 

 in birds. 



EiBL-EiBESFELDT (Added later): I can confirm Dr Thorpe's statement that Dr 

 Lehrmann does not take this extreme view now. I discussed the matter with him 

 in Cambridge at the Ethological Conference. 



Grastyan. I would like to know in more exact terms what is meant when you 

 say that the animal learns quickly — How many trials ? 



Eibl-Eibesfeldt. It has to kill four or five rats to learn how to kill. 



Grastyan. If it cannot kill the first time, what happens in the next trial? 



Eibl-Eibesfeldt. He tries again. If he receives a punishment stimulus, he learns 

 faster. 



Grastyan. What happens if you work with a satiated animal? 



Eibl-Eibesfeldt. It kills anyway. It was shown by Kuo that in cats the satiation 

 has no influence on hunting behaviour. I still would like to ask why Dr Hebb teels 

 that it is not justified to speak of instincts as innate behaviour in contrast to a 

 learned response? 



