34 JOSEPH PETERSON 



at the corner of the maze before cul de sac 1, and that since the 

 turns were so close together they tended very persistently to 

 fuse together into a single turn of 180 'degrees, thus taking the 

 rat into the blind alley. It was very interesting to see certain 

 rats continue to run into 1 with almost monotonous regularity 

 for three weeks, three trials each day, while other errors, errors 

 of entering other cul de sacs, occurred very seldom. Thus from 

 the 10th to the 79th trial, inclusive, rat 9 made 60 errors of 

 entering 1 with only 11 entrances to all the other nine blind 

 alleys ; rat 1 1 from the 24th to the 83rd trials made corresponding 

 errors of 47 to 15. 



In the A-mazes cut de sacs 5 and 6 were likewise entered 

 fewer times and eliminated more easily than 1, 2, and 3, all 

 of length equal to that of 5 and shorter than 6. It is, of course, 

 not contended here that the two sets of blind alleys compared 

 are of equal difficulty in all respects other than that here con- 

 sidered. At the same time, they may be approximately equal; 

 that is a matter which can be determined only empirically. 



The accompanying table (table IV) shows that not only is 

 the number of entrances to blind alleys first to be passed along 

 the true path greater than that nearer the food box, but also 

 that the percentage rate of elimination is greater in the latter. 

 This is shown by comparing the number of entrances to the 

 different groups of cul de sacs in question for different successive 

 periods in the learning process from the first to the last trial. 

 In the first five trials of all the animals, trained and untrained, 

 the average number of entrances per trial into cul de sacs 1-4 

 of the B-mazes is twice that of entrances into 6-10. Calling 

 these numbers for the first period (the average of the 1st to the 

 5th trial) 100% each, to get a common basis for comparison, 

 we find that there is a much more rapid percentage drop of elim- 

 ination of entrances in the case of the blind alleys nearer the 

 food box. Since the trained rats discontinued the experiment 

 with the 25th trial without finishing the habit, the percentages 

 for the two groups in the B-mazes are not correct after the 

 25th trial, though they are strictly comparable. An additional 

 line is given, in the case of each of these groups, of the accurate 

 percentages of elimination of entrances for the untrained rats 

 (eight in each group) alone. It will be noted that in the case 

 of the five cul de sacs nearest to the food box the percentage 



