160 Many Kinds of Habits 



Many other animals can master simpler labyrinths 

 and can retain their mastery for a month or more 

 without further practice. It has been proved that a 

 rat can master a labyrinth without any cues from 

 sight, smell, or touch; but in ordinary cases various 

 sensory hints, especially those of touch, seem to be of 

 great importance in the establishment of the habit. 

 What eventually happens, however, when the habit 

 is perfect and the creature moves rapidly through the 

 passages, is that the guiding cues derived from out- 

 side (through "extero-ceptors") are replaced by 

 guiding cues from inside (through "propriocep- 

 tors"). That is to say, the linkages are kept right by 

 hints from the muscles, tendons, and blood-vessels. 

 A habit has taken a firm grip when cues from within 

 replace cues from without. 



Habits may be graded in other ways, and most 

 important of all, were it not so difficult, is a classifica- 

 tion from the psychological side. There are some 

 habits, say the elephant's routine in putting the 

 penny into the cash-box, which owe their establish- 

 ment to mere repetition. But in many cases the animal 

 recognizes some measure of significance in the se- 

 quence of events, and this recognition, say of rewards 

 and punishments, helps the habit-forming. In many 

 cases, also, as when an animal learns to do a certain 

 thing on hearing a certain sound, there is association- 

 memory, and in other cases, perhaps, higher forms 

 of memory. When the first links in a habituation- 

 chain have been activated, it is easy for other links 

 to follow, and in this sense there is a certain inertia in 



