TIME 



PER 



DAY 



RATIOS OF TESTS VS CONTROLS 



SCALE OF RATIOS 



EXCLUDING FAILURE RATS 

 INCLUDING FAILURE RATS 



DAYS OF TRAINING 



ALL STRAINS 



DAYS OF RETENTION 



Fig. 4 Ratios of the time averages of the tests vs. controls on each day of 

 training and retention. The base line represents equality, i.e., ratio of 1.000; 

 points above the base line represent 'plus' ratios, those obtained when the test 

 average was larger than, and so divided by, the control average; points below 

 the base line represent 'minus' ratios, those obtained when the control average 

 was larger than, and so divided by, the test average. Accordingly, points above 

 the base line show that the tests took more time. The heavy lines are based on 

 the 'completes' and 'incompletes'; light lines, upon the 'failures' as well. Units 

 on the base lines are days: first series for training; the second series, retention; 

 units on the vertical scale gives the size of the ratios. 



236 



