IV. 



EXPERIMENTAL RESULTS 



i. The Influence of the Time Interval in Successive Associa- 

 tion upon the Rate of Learning. The experiments bearing di- 

 rectly upon this problem may be divided into two sets : A. Those 

 in which the association was learned in the forward direction; 

 B. Those in which the association was learned in the backward 

 direction. Groups I to XII were tested in the first set and Groups 

 XIII and XIV in the second. All the animals were of about the 

 same age and health conditions. Twenty trials were given each 

 day. To have mastered the problem the animal must have made 

 not less than 90 per cent of correct responses over a period of 

 five consecutive days, i.e., 90 per cent on the last 100 trials. 



A. Learning the Association in the Forward Direction. As- 

 sociations were made between stimuli from different sense fields. 

 Two pairs of stimuli were used : a) auditory (buzzer) and pain 

 (electric shock), and b) visual (light) and auditory. The 

 auditory-pain experiments are presented first. 



a) Association of buzzer with electric shock. In order to se- 

 cure comparative data upon the influence of the time interval 

 between the presentation of buzzer and the presentation of pain, 

 the animals, upon mastering the problem of negative response to 

 pain, 1 were divided into groups, and each group was set to work 

 to transfer this negative response from pain over to the buzzer. 

 The sound was always presented before pain but in a different 

 temporal relation to pain in each of the groups. Other factors 

 remained constant for all of the groups. In addition to present- 

 ing the stimuli in immediate succession, i.e., in temporal contact, 

 presentations at intervals of one, two, four, and six seconds were 

 made. In all, 38 animals were used. 



i ) Continuous presentation. Group II was trained on buzzer 

 followed by the pain immediately. The results of the work of 

 this group are summarized in Table II. 



1 See division 3 of this section. 



