148 Habit and Instinct. 



as to its essential importance in the more primitive 

 psychology of such animals as young birds. When chicks 

 learn rapidly to distinguish between the caterpillars of the 

 cinnabar moth and those of the small white butterfly, so 

 that they gobble up the one without hesitation and avoid 

 the other without fail, they give the plainest intimation 

 that an association has been formed in each case 

 between appearance and taste. Prof. Preyer notes 

 that his chicks rapidly learnt to associate the sound 

 of tapping with the presence of food. I have already 

 described how one of my chicks, which had but recently 

 learnt to drink, standing in its tin, subsequently stopped 

 as it ran through the water in such a way as to lead one 

 to infer that wet feet had become associated with the 

 satisfaction of thirst. Young pheasants seemed to associate 

 water with the sight of a toothpick, on which I gave them 

 some drops. Ducklings so thoroughly associated water 

 with the sight of their tin that they tried to drink from it 

 and wash in it when it was empty, nor did they desist 

 for some minutes. A moorhen chick, for whose benefit we 

 had dug up worms with a spade, and which, standing by, 

 jumped on the first-turned sod and seized every wriggling 

 speck which caught his keen eye, would soon run from 

 some distance to me as soon as I took hold of the spade. 

 There is no need to multiply instances. The study of young 

 birds is an impressive lesson in association psychology; 

 and one daily grows more convinced of the importance of 

 association in the acquisition of experience of this homely 

 and elementary but essentially practical kind. 



But it may be said that though association is unques- 

 tionably important, yet its efficiency in the guidance of 

 action depends upon something deeper still. Granted 

 that, in a chick which has first seen and then tasted a 

 nasty morsel, an association is formed between sight and 



