12 JOSEPH PETERSON 



far as they go, as the two comparable groups had identical 

 experiences. 



Since the A-mazes were cleared earlier than the B-mazes, it 

 was possible to put into them, as indicated in the schedule, 

 some of the females — four on each A-maze — which first com- 

 pleted their original problem. 13 Finally, — -leaving out the female 

 12, which did not complete its original problem until the maze 

 was taken over for the males, and the small male 10, which 

 had been running with the female group Mm — three females 

 were practiced on each of the A-mazes by the intensive method. 

 The results of these two groups are, for obvious reasons, strictly 

 comparable only to the twelfth trial inclusive, when the rats 

 in the II A maze had completed their problem. 



All comparable, or control groups were then run on the same 

 days, the same number of times, and as nearly as possible the 

 same time of day. Moreover, to give no possible advantage 

 of trailing to either group — and aside from the cases noted, 

 not between control groups, no such behavior was observed — the 

 group which was practiced first one day was second the next. 



Both time and error results were noted. The experimenter 

 devised a system of short signs with which to record the com- 

 plete gross behavior of each animal. Returns in the maze were 

 noted as accurately as possible; only minor ones not reaching 

 cul de sacs or corners of the various maze alleys before being 

 corrected were left out of the records. Entrances into the blind 

 alleys were all classified by means of appropriate signs, into 

 three classes, — complete entrances, entrances about half way in, 

 and beginning entrances bringing the animal's head and fore 

 part into the blind alley while the hind feet remained in the 

 true path. In the table of results these entrances constituting 

 the last class are in the column headed " Start." It was also 

 noted, as the animal emerged from the cul de sac, whether it 

 continued forward toward the food or turned back toward the 

 place of beginning. Hesitancies were also noted. Of these a 

 peculiar and amusing kind was frequent. Occasionally, an 



13 To be sure that the two groups were of approximately equal ability the ani- 

 mals composing them were selected as follows: The first, third, fifth, and seventh 

 rats that completed Maze I IB were selected for Maze I A, with the long cul de sacs- 

 and the second, fourth, sixth, and eighth were taken for Maze IIA. In case of 

 any slight difference in the groups this would put the better animals into the more 

 difficult maze, so that the better results expected for IIA. could not be due to 

 superior animals. 



