TABLE OF CONTENTS 



Page 



I. Introduction 1 



II. Critical Review of Historical Data 2 



1. Imitation 3 



2. Use of tools 5 



3. Dreams 8 



4. Learning curve 8 



5. Memory 9 



6. Thorndike's test 10 



7. Learning by being "put through" 14 



8. Recognition 16 



9. Rate of forgetting 16 



10. Association by similarity 16 



11. Reluctance and expectancy 17 



12. Varying means to the same end 17 



13. Reactions to a temporal series of colors 19 



14. Washburn's cat on the stairway 20 



III. Notes on the Animals and Children Tested 21 



IV. Apparatus and General Method 22 



V. Experimental Results .30 



1. Tests with animals 30 



A. Learning the association 30 



(a) Rats .30 



(b) Dogs 32 



(c) Raccoons 33 



(d) Summary 34 



B. Maximal intervals of delay attained 35 



(a) Group differences in maximal delay 35 



(b) Effect of size of release upon delay 37 



(c) Effect of backgrounds of different brightnesses upon 



delay 38 



(d) Effect of number of boxes upon delay 39 



(e) Effect of other conditions upon delay 39 



C. Methods of reaction after delay used by animals 39 



(a) Orientation of whole or part of body 40 



(b) Position in the box 47 



2. Tests with children 52 



A. Method of experimentation 52 



B. Are the results obtained from animals and children com- 



parable? 53 



C. Learning 55 



D. Differences between the learning of animals and children ... 55 



E. Delayed reactions 57 



VI. Theoretical Considerations 62 



1. The cues essential for correct delayed reactions 62 



A. Substitutes derived from the external environment 63 



B. Substitutes derived from within the subject's body 67 



(a) The type of internal cue used 67 



(b) The mechanism by which internal cues guide behavior 70 



2. The place of ideas in the grades of animal learning 73 



VII. Summary and Conclusions 79 



VIII. Appendix 82 



A. Detailed records of two rats and two raccoons 82 



B. Notes on raccoons 85 



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