76 BRAIN MECHANISMS AND LEARNING 



and p. caeriileiis) in Britain, can hardly have failed to have been impressed 

 by the smooth easy certainty with which the complete act is accomplished. 

 Under these conditions one seldom sees anything so suggestive of trial 

 and error learning. On the contrary, the act appears at first sight to be a 

 real and sudden solution of the problem from the start, as if the bird, 

 before responding to the string at all, had seen the answer to the problem, 

 and as if its behaviour was the planned result of this insight. But when one 

 comes to investigate the development of such behaviour in the nidividual, 

 one gets a very different picture. Far from it being a smooth and easy 

 response, one fmds instances of birds which learn with extreme slowness 

 and difficulty, acquire some part of the response only to lose the abihty 

 again, or get to a certain point in the acquisition of the trick and arc unable 

 to complete the learning. 



One point that emerges clearly, however, is that it is much easier — 

 other things being equal — for a bird to take food from a short string 

 than a long one ; and that an essential stage in the training of birds to feed 

 by pulhng up strings is to get them to take food from a short string, say 

 2 inches long, where the seed is reached without the necessity of actually 

 pulling in the string. Once this has been achieved, the problem posed by 

 an increase of length to 2| inches, which must then be pulled in before the 

 seed can be eaten, is a relatively easy one; although it of course imme- 

 diately brings in a new movement, that of holding the string. Once the 

 string has been held and the bait secured in this manner, a gradual increase 

 in the length of string can very often be made without causing the bird 

 any great further difficulties or setbacks. 



Prehminary observations at the Madinglcy Field Station for the study 

 of Animal Behaviour, Cambridge University, with captive wild-caught 

 and hand-reared tits and finches, gave puzzling irregularities, uncertainties 

 and differences in individual and specific behaviour. It was clear that 

 many more factors were coming into the process of acquiring this rather 

 striking new feeding technique on the part of the birds and that a careful 

 experimental study of it might be expected to give results not merely 

 of interest to the ornithologist, but of wide application to problems of 

 animal learning in general; and possibly even to bear on problems of 

 human learning. Miss M. A. Vince of the Cambridge Department of 

 Experimental Psychology and of the Madingley Field Station accordingly 

 took up this study which, although far from complete, has already 

 yielded results of remarkable interest (Vince, 1956-59 and in press). First 

 experiments with adult wild-caught great tits showed that the bird's 

 first response to the experimental set-up was to keep away from it, but 



