382 HARVEY CARR 



fact a positive correlation of .60 obtains between the ability 

 to master the problem and the degree of disturbance due to the 

 introduction of novel conditions during the interval of delay. 

 In other words, those rats that rely mainly upon motor atti- 

 tudes learn quickly and display the most disturbance when 

 these motor attitudes are altered. On the other hand a negative 

 correlation of .48 obtains between speed of learning and the 

 degree of disturbance due to an increase of the time interval. 

 Those rats that rely mainly upon the sensory aspects of the 

 previous act in the solution of the problem are relatively slow 

 learners and exhibit the greatest disturbance when this time 

 interval between the stimulus and the response is increased. 



FUNCTION OF VISION 



The group of eight rats contained three blind animals. The 

 records of the two groups were compared. The individual 

 records are so variable and the numbers in each group are so 

 few that it is impossible to make assertions with any degree of 

 confidence. In general the group differences that exist are so 

 small that they may well be due to chance or individual differ- 

 ences. Consequently the data as given justify the following 

 negative conclusions. 1. The presence of vision did not influence 

 the rate of learning. 2. No differences in the type of curve 

 were apparent. 3. There were no manifest differences as to 

 the interrelation of the R and the L habits. 4. No assertions can 

 be made as to any differences of ability in mastering the initial 

 choice for each day, or as to the relation between this choice 

 and the day's success. 5. No differences were manifested in 

 the mode of attack, or the ability to adapt the alternate choices 

 to the objective sequence. 6. The groups did not differ as to 

 the relative reliance which they placed upon the two sets of 

 guiding stimuli. 7. No assertions can be made as to any differ- 

 ences of ability in solving the problem of increasing intervals 

 of delay. It is of course possible that some of the above con- 

 clusions will need revision provided larger groups of animals 

 are tested. 



Two differences were detected. 1. The blind animals were 

 somewhat the slower in movement and expended more time in 

 making each run. The average time values per run were 6 

 and 7.2 seconds for the normal and the blind animals respec- 



