TABLE OF CONTENTS 



PAGE 



I. Introduction i 



II. Historical 3 



III. Apparatus and Method 13 



IV. Experimental Results 19 



1. The Influence of the Time Interval 19 



A. Learning the association in the forward direc- 



tion 19 



a) Association of sound with pain 19 



b) Association of light with sound 24 



B. Learning the association in the backward di- 



rection 30 



2. Simultaneous vs. Successive Presentation 35 



3. Learning the Negative Response to Pain 39 



V. Interpretation of Results 44 



VI. Summary and Conclusion 50 



