2i8 O.C. Glaser 



of the process, for movements are never without cause, and the 

 stimulus is aggravated, alleviated, or unchanged by them. What- 

 ever be the result of the movement, the animal "learns" what has 

 been the effect upon the stimulus, the cause of the movement. 

 Two criticisms may be made of this point of view: In the first 

 place, in behavior such as that of an ophiuran, movements which 

 fail to solve a specific problem, or to contribute anything whatever 

 to its solution, are often repeated immediately. If the animal 

 learned anything from them, it forgot what it learned at the 

 instant of learning, for the intervals between two successive move- 

 ments which fail for the same reason mi, y be less than one second; to 

 forget as rapidly as to learn, can be objectively recognized as 

 neither. In the second place, in ophiurans at least, it is the excep- 

 tion for an animal to perform only one movement at a time. 

 Usually a considerable number, four, five, or six distinct move- 

 ments are performed synchronously. All of these, on the assump- 

 tion I am criticising, result in learning, but the knowledge which 

 they give may be of two sorts; some of the movements may tell 

 the animal how to solve the problem, the others, how it cannot be 

 solved. It is impossible for me to believe, without striking evi- 

 dence to the contrary, that an ophiuran can learn at the same 

 mstant half a dozen facts, belonging some to one, some to the 

 other of two distinct categories. 



If the idea that mere movement in various directions is a sign 

 of learning, involves the serious difficulties which it seems to me to 

 mvolve, we have nothing but behavior more or less permanently 

 modified as the result of experience to fall back upon. I have 

 shown that under ordinary circumstances Ophiura brevispina does 

 not improve with practice, in its righting behavior, and in problem 

 solving it shows no greater aptitude. I am, therefore, forced to the 

 conclusion that neither intelligence nor even learning have as yet 

 been demonstrated in this animal. 



My experience with ophiurans also leads me to the conclusion 

 that resolution will be very difficult to demonstrate, not only 

 because of those sudden changes in behavior for which it is difficult 

 to assign causes, but also because of the remarkable "action sys- 

 tem" exhibted by these animals. This action system shows better 



