72 BRAIN MECHANISMS AND LEARNING 



submissive posture in the turkey cock but the peacock unable to 'understand' 

 continues fighting and the more he beats the turkey cock the more the latter gets 

 latched in the mechanism of the submissive posture. He does not run away and 

 often a fatal end results. Another example of innate behaviour misleading in 

 artificial circumstances normally not occurring in nature is the light orientation of 

 mail)- insects which leads them to circle around lamps and burn to death. 



Concerning the previous remark of Dr Hcbb, I want to add that he himself 

 speaks of how closely 'the two' collaborate, referring to innate and acquired 

 patterns. Evidently he makes a distinction and only avoids the terms innate and 

 acquired. We use them as we feel a need to distinguish those behaviour patterns 

 which show adaptcdness to specific environmental situations without the animal 

 having experienced this situation before, from those behaviour patterns which are 

 learned by the animal by active communication with the environment during 

 ontogeny. We do not know if they are based on two different kinds of mechanisms 

 and our term does not imply it. It is probable but still needs to be analysed. The 

 separation of both by experiment is a first step towards such an analysis. 



LissAK. The other side of the question is the humoral or hormonal background. 

 May I mention that well-known experiment of Richter and the mouse-killing or 

 frog-killing test of the lactating animal. The maternal aggressivitv can be avoided 

 by a simple injection of ocstrone or by destroying the amygdalate. I suppose that 

 the hormonal afterentation must have a very important role in such aggressiveness 

 or killing experiments. 



EiBL-EiBESFELDT. There exists a paper published by Roller some years ago, dealing 

 with the hormonal control of nest-building behaviour. 



LissAK. His method is very convenient for studying the humoral mechanism too. 



Magoun. Are physiologists making an effort to identify activity of the C.N.S. 

 associated with such behaviour? 



EiBL-EiBESFELDT. Dr vou Holst Studied brain mechanism by stimulating certain 

 areas in the brain of the domestic fowl — and he released several highly complicated 

 behaviour patterns. He will present a paper at Cambridge in September. 



Thorpe. I would like to comment on one aspect which seems important in this 

 question of learned and instinctive: that is the complexitv of the stimulation to 

 which the animal is exposed. If a bird is raised in a sound-proofroom and it sings 

 a normally elaborate song we are justified in saying that this is innate because there 

 is no corresponding complexity in the environmental situation to wliich the bird 

 is exposed which could have called forth the behaviour. One must assume that any 

 observed complexity must come from somewhere; in this case from the animal 

 itself If on the other hand you can find a sufficient complexity in the sensory input 

 to which the animal has been exposed you are inclined to put it down to the 

 account of experience. This is a very important fundamental distinction between 

 the two points ot view. The essential point is the origin of complexity in behaviour. 

 In so many examples of animal behaviour environmental stimuli may be acting as 

 triggers to set off^ complex behaviour patterns but they are not such that they can 

 be regarded as the full 'cause of the behaviour; the complex adjustment of it must 

 be sought elsewhere and in such circumstances we are fully justified in regarding it 

 as internal and in labelling the behaviour as innate. 



Hebb. To add to the question asked by Dr Magoun, I think that it is relevant to 

 mention the extensive neurolosiical investitrations b\' Beach made on instinctive 



