Fear thresholds were measured in four experiments by exposing rats to electric shock in order to determine the maximal intensity rats would tolerate rather than enter a fear-arousing box and/or stop freezing. Increasing fear raised these thresholds. They were greater for rats having to escape shock to a fear-arousing box than for rats having to escape shock and fear to a neutral box. The forgetting functions for the latter two groups differed: the first group yielded a monotonic decay function, whereas the second group yielded an inverted U-shaped function. These thresholds decreased as a function of an avoidance learning procedure. Rats that had to escape shock to a fear arousing box did not do so immediately, although they had stopped freezing. An avoidance-avoidance conflict explanation for immobility was not found to be valid. A theoretical formulation based on the following two hypotheses was suggested to explain these results: the fear-aroused freezing (immobility) is an unlearned response; finding a way to escape the source of fear starts another unlearned response, withdrawal.
Bibliographical noteFunding Information:
This paper is based on a doctoral dissertation done at the Department of Psychology, the Hebrew University, Jerusalem. Israel. The research was supported by the Kaplan School of Economics and Social Sciences. The writing of this paper was funded through the University of Haifa. The author would like to express his gratitude to C. Greenbaum from the Hebrew University and to D. Samuel from the Weizmann Institute. for their supervision and guidance in all phases of this study. Special thanks to R. Guttman. head of the animal laboratory.
ASJC Scopus subject areas
- Health(social science)
- Neuropsychology and Physiological Psychology
- Experimental and Cognitive Psychology
- Developmental and Educational Psychology