average of two hundred seventy thousand. 



The average mean variations for the group are: 



Trials '60 ± 1 23;i Variation 



Time 224 min. ± 125 min. 55^ " 



Distance 271.6 m. ± 59. Q m. 22^ " 



The distance variation is the least, which confirms the state- 

 ment male above, to the effect that distance is the most relia- 

 ble neasure of learning ability in such a problem as the pres- 

 ent one. Ho very close relation seems to obtain between the 

 number of trials required for finishing the problem and the 

 total amount of time or distance. Thus the rat which finished 

 in fourteen trials had the highest total time record in the 

 group, and a high distance record, while the rat which finish- 

 ed in fifty-one trials had the highest distance record, but 

 a mean time record. The lowest time record was made by a rat 

 finishing in twenty-four trials whose distance record was also 

 low; the lowest distance record, by a rat requiring eighteen 

 trials for the problem, whose time was lower than the average. 

 Reference to the columns in the table which show the mean var- 

 iation for each rat in time, distance, and trials will empha- 

 size the lack of regularity just mentioned. Except where the 

 time values are very hip;] , time and distance bear a fairly con- 

 stant ratio to each other. The exceptions occur when the time 

 record is increased on account of failures (each of which means 

 a count of 900 seconds ) in the first part of the learning 

 process. In a trial which has one or more failures as a com- 



