EFFECT OF LENGTH OF BLIND ALLEYS ON ^L\ZE LEARNING 25 



exceptions, have directions such as to favor returns in the case 

 of a rat emerging from them. This more rapid decrease in 

 returns than ' in entrances to cul de sacs is least comphcated, 

 and also shown most emphatically, in the case of the complete 

 entrances to cul dc sac 1, which is encountered before the rat 

 could be confused by running into any other blind alleys. Figure 

 II shows the matter graphically. Curve CE represents the 

 number of complete entrances of eight untrained rats to the 

 first blind alley at full length, as in Maze IB; curve R, the 

 returns; and 2R, twice the returns. 2R is a better curve for 

 comparison with CE because originally, i. e. before an animal 

 is at all practiced, about half of the entrances are followed by 

 returns; twice the returns, therefore, gives a number initially 

 about equal to the total number of entrances. Figure III gives 

 corresponding curves, C'E', and 2R', respectively, for the same 

 number (eight) of untrained rats in cul de sac 1, shortened from 

 22 inches to 8.5 inches. Here the same result is evident: while 

 the elimination of entrances is far more rapid than in the case 

 of the longer blind alley, the returns are still more rapidly reduced 

 as shown by the 2R' curve. 



It may also be noted here under our first point that the 

 returns in both the B-mazes persisted longer in the cases of the 

 blind alleys farther from the food box than of those near it. 

 That is, returns from blind alleys first encountered were less 

 easily eliminated, as were also entrances, than from those further 

 along the true path. This is true even in cases of blind alleys 

 nearer the food box that were comparatively long, as 7 and 8, 

 even though, as in the case of 8, the direction of movement 

 in emerging from the cul de sac favored returns. It is barely 

 possible that an odor factor may have entered in case of 8. 

 The mazes I A and II A are not so well adapted to show these 

 relationships, as there are few^er blind alleys of various individual 

 differences of complexity, but the same conclusions as those 

 given for the B-mazes may also be made for them. 



A second important point to note is, that the nature of the 

 response to a blind alley gradually changes with practice, as 

 well as the relative number of entrances into it. This change 

 in the nature of the response is more marked in longer than in 

 shorter blind alleys, particularly in those whose elimination was 

 most difficult. It is illustrated best in the data from cul de sac 



