CONTENTS 



I. Historical 1 



II. Statement of the Problem 3 



III. Methods of the Experiment 4 



IV. Tests of Learning Ability 6 



(a) In the Maze 6 



(&) In the Multiple Choice Apparatus 6 



V. Experimental Results 9 



(a) Time and Error Averages for all Tests 9 



(&) Difference in Learning between Families of White 



and Yellow Mice 9 



(c) Results for Maze Test 11 



(1) The Initial Learning 11 



(2) The Interference 17 



(3) The Retention 18 



(d) Results for Multiple Choice Test 20 



VI. Correlations in Learning Records between : 



(a) Time and Error 23 



(&) Performance at Beginning and End of Tests 24 



(c) Initial Learning Records and Retention 24 



(d) Performance in Maze Test with Performance in Mul- 



tiple Choice Test 26 



VII. Family Resemblances 26 



Mean Variations for Related and Unrelated Individuals . . 27 



VIII. Sex Differences 29 



(a) Differences in Time and Error Records 29 



(&) Comparative Distributions of the Males and Females. 30 



(c ) Variability of the Sexes 33 



IX. Individual Differences and Methods of Habit Formation . . 35 



X. Health Conditions and Learning Ability 42 



XI. Family Histories 44 



XII. Summary and Results 



