332 'Journal of Coniparative Neurology and Psychology. 



pedals bearing plain pedal cards. The white sign board was kept 

 suspended above the row ot pedals throughout this series of experi- 

 ments. The animal was given i6o trials, 20 a day. In calculat- 

 ing results an error was recorded for each attempt to escape by 

 striking an unattached pedal. If the animal struck the attached 

 pedal first during a given trial a "correct first choice" was record- 

 ed for that trial (see table). Time measurements proved to be 

 of absoultely no value, since the animal sought the pedals as his 

 means of escape from the start, and was so dexterous in passing 

 from one pedal to another that there was no essential difference 

 between the time of escape when there were no errors, and when 

 there were several. Besides, as there was no pressing desire to 

 escape, conditions external to the interests of our problem deter- 

 mined the length of his stay in the cage. He always came out 

 directly the shock of the discharged trigger was felt, but often he 

 wandered about the cage contentedly before attempting to escape. 

 As a rule he was fed before experiments were begun; the only in- 

 centives for escape which the experimenter supplied were a few 

 much gnawed bones and a commending caress. It has been my 

 experience that a well fed, contented dog, if undistracted by other 

 sense-impressions than those of the experimental situation, is apt 

 to inspect his immediate environment quite thoroughly, and to act 

 with more appearance of caution than has been reported by pre- 

 vious experimenters with these animals When put into the cage 

 for his first trial the dog went directly to the attached pedal, struck 

 it, and came out. Of course his previous experience easily ac- 

 counts for his having struck at the first projecting object that 

 came his way, and I do not doubt that his immediate success in 

 getting at the attached pedal was accidental. When he was put 

 in for the second trial he went at once to the pedal that had just let 

 him out and struck it, then started for the door; the white pedal 

 card was now on another pedal, and that pedal alone was attached. 

 But the animal did not seem to take the directing pedal card into 

 account, for he returned to the unattached pedal again and again, 

 striking it more forcibly each time, and always running to the door 

 after each attempt. After ten such attempts he sat down by the 

 door and began to whine. He was spoken to reassuringly, after 

 which he returned to the pedals and inspected them. After some 

 hesitation he struck the attached pedal, thus releasing himself. 

 His behavior during the remainder of the 160 trials showed nothing 



