DISCRIMINATIVE ABILITY OF THE TURTLE 7 



become sufficiently docile to allow of satisfactory experimen- 

 tation. Most of my turtles, however, finally became so tame 

 that they could be handled gently without alarm and would 

 take food readily, even while being held in the hand. A well 

 conditioned Chrysemys is a voracious feeder and if not allowed 

 to gorge unduly will be eager for a daily ration of food. It is 

 an active turtle and when well tamed will swim or crawl rapidly 

 to the edge of the aquarium in hope of food whenever anyone 

 approaches. For these reasons it makes a fairly satisfactory 

 experimental animal. Feeding can be used as a reward in the 

 formation of associations and tests can be conducted with a 

 fair degree of rapidity. These statements, however, apply only 

 to turtles which are well tamed and in a satisfactory physiolo- 

 gical state. No animal is more unsatisfactory or taxes the 

 patience of the operator more severely than a disgruntled 

 turtle, whether its sulkiness arises from fear or from physical 

 disability. 



In describing experiments the term "trial " is used to express 

 one individual attempt to choose between electric and food 

 box. A series of successive trials, usually ten in number and 

 immediately following each other, is denominated a "test." 

 As a rule one test per day was given and upon successive days. 

 In certain cases they were given less often, particularly when 

 a turtle's eagerness for food became lessened. As may be noted 

 from the tables, twenty trials were sometimes given at a test. 

 It was thought that a larger number of trials per day might 

 give better results, but the records show no more than a pro- 

 portionate acceleration in learning. In all cases an effort was 

 made to subject the animal to tests and trials occurring with a 

 fair degree of regularity. 



In practice the turtle to be experimented upon was gently 

 removed from the aquarium and placed in the entrance room. 

 The operator then retired behind the screen having assured 

 himself that the boxes were properly placed and baited and the 

 electrical apparatus adjusted as desired. Food was always 

 placed in both boxes so that its odor, if appreciated, might 

 not serve as a clue. By pulling a string from behind the screen 

 the slide was then raised between the entrance room and the 

 runway and the turtle thus given opportimity to approach the 

 boxes. This might occur immediately or be somewhat delayed 



