CHAPTER XII 

 THE MEMORY IDEA 



92. Evidence for and against Ideas in Animals 



IN the last chapter we have seen that the behavior of the 

 lower forms of animal life, at least, can be fully explained 

 without supposing that the animals concerned ever consciously 

 recall the effects of a previously experienced stimulus in the 

 entire absence of the stimulus itself. We must admit that it 

 is not easy to prove the possession by any animal of memory 

 in the sense of having ideas of absent objects, rather than in the 

 sense of behaving differently to present objects because of past 

 experience with them. The dog shows clearly that he remem- 

 bers his master in the latter sense by displaying joy at the 

 sight of him. Can we be sure that he has remembered him 

 in the former sense during his absence ; that is, that he has 

 had a memory image of him? Certain pieces of negative 

 evidence have been noted. Where an animal learns to work 

 a mechanism by gradually dropping off unnecessary move- 

 ments, it looks as if its conduct were not guided by an idea of 

 the right movements, for the association of ideas as we know 

 it is so rapid a process that a single experience of two stimuli 

 together is enough to enable one to revive the other in the form 

 of a memory idea, provided that the experience was recent. 

 When an animal hag learned to run through a complicated 

 labyrinth almost without error, but still persists in taking the 

 wrong turning at the outset, we are surely justified in saying 

 that if it has ideas, it does not use them as a human being 

 would, for some kind of idea of the right way to start the laby- 



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