HABIT FORMATION IN THE FIDDLER CRAB 235 



The individual records presented above are summarized in 

 table 4. 



Table 4 shows (1) that none of the individuals experimented 

 with ever made fewer open attempts than it made on the first 

 day, (2) that the maximum number of open attempts approx- 

 imates those of the last day, (3) that the greater the number 

 of days an animal was tried, the greater the gain. Number 10, 

 which was tried at irregular intervals, lasting for a period of 

 eighteen days, gained less than any other individual. To be 

 sure, considerable variation in the rapidity of habit formation 

 is exhibited, some of the crabs made their maximum number of 

 open trials about the sixth day, while others did not succeed 

 in learning the direction of the open corner accurately until 

 the last day. Habit formation, like any other character, is 

 subject to the law of variation, being stronger in some individ- 

 uals than in others. 



It is evident, however, that the fiddler crab can overcome his 

 proclivity for one direction, and learn to go in the opposite one, 

 if the latter enables him to escape from a trap. The mere fact 

 that after encountering the glass obstruction, the animal goes 

 to the open side, is in itself significant. The experimenter was 

 obliged to drive the animal away from the closed end in the 

 very beginning of the experiment. After the first ten. attempts, 

 it learned to find the opening by itself. But the ability to over- 

 come its inclination almost entirely, making 90% of its move- 

 ments in the direct ; on which leads to escape, is unmistakable 

 evidence that the fiddler crab possesses associative memory. 

 To be sure, it learns slowly, perhaps more so than the crawfish, 

 but it should be remembered that the crawfish showed no 



