VALUES OF CURVES OF LEARNING 147 



The error and distance curves are practically identical with 

 exception that the error curve is the more irregular and variable. 

 This coincidence experimentally confirms our previous state- 

 ment that the error curve must approximate the distance curve 

 as a limit when returns are included in the error record and when 

 small segments of the maze are taken as the unit The slight diver- 

 gence between the two exemplifies the fact that runways are not 

 eliminated as wholes but progressively. The distance curve 

 thus represents more adequately the details of this eliminative 

 process inside an alley. The two curves so closely coincide, how- 

 ever, that errors, according to our definition, may be regarded 

 as a practicable substitute for distance. This fact is important 

 in view of the many difficulties involved in recording and manip- 

 ulating the distance data. It is evident that a marked divergence 

 between the two curves must result when errors are confined 

 to ciil de sacs and no attempt is made to evaluate different 

 degrees of error. A curve constructed according to the older 

 practice cannot adequately represent the progressive elimination 

 of surplus distance. 



An inspection of the curves reveals the nature and extent of 

 the independent variability of time and distance. These vari- 

 ations may be classed as either gross or minute, i. The gross 

 variations consist of a very rapid decrease of time relative to 

 distance during the first eight or nine runs. From this point on 

 to the tw^enty-fifth trial, distance is eliminated slightly faster 

 than time. After the twenty-fifth trial, any variability is too 

 small to be of importance. 2 . Minute variations of a very irregular 

 character occur throughout the entire length of the curves. 



The gross variations force one to the conclusion that time and 

 distance represent either different features of the learning process, 

 or else the same features to varying degrees. An analysis of the 

 maze problem and an observation of the rat's behavior indicate 

 that the maze presents to the rat four factors to be learned: 

 first, the elimination of errors; second, the inhibition or elim- 

 ination of the natural tendencies of timidity and curiosity in 

 new situations; third, the association between food and the 

 maze; fourth, increased speed of running. We wish to advance 

 the propositions that the gross difference between time and 

 distance is due to the fact that distance represents but one of 

 these factors, w^hile time represents all four, and hence that the 



