Defense Date


Document Type


Degree Name

Doctor of Philosophy


Clinical Psychology

First Advisor

William M. Kallman


This research represented an extension of previous work on the therapeutic application of the external inhibition phenomenon, and sought to examine the effects of such a procedure on the verbal- cognitive, motoric, and physiological components of the anxiety response. To accomplish this, subjects were selected and treatment effects evaluated on the basis of changes elicited in each of the three response modalities by a specific fear stimulus, The relative effectiveness of the external inhibition treatment in modifying the multiple components of the anxiety response was examined by a comparison with procedures controlling for expectancy effects and repeated exposure to the phobic stimulus.

A series of hypotheses were derived which predicted that the external inhibition treatment would produce significant reductions in the self-report, behavioral, and physiological channels being assessed. It was also predicted that these reductions in anxiety for subjects receiving the external inhibition treatment would be significantly greater than those evidenced by subjects receiving procedures designed to control for expectancy effects and repeated stimulus exposures.

Subjects were 24 female undergraduate students enrolled at Virginia Commonwealth University who were selected from a pool of 316 females who answered the Spider Questionnaire (Klorman, Weerts, Hastings, Melamed, & Lang, 1974). Three separate selection criteria were utilized to help insure that only those subjects who were highly fearful of spiders were selected for participation in the study: (1) a total score on the SPQ that was within the upper 25% of the distribution of scores on the SPQ, (2) a distance score of at least 24 inches on a passive behavioral avoidance test (BAT), and (3) an increase in heart rate of at least 10% during the initial exposure to the spider. Eight subjects meeting these criteria were randomly assigned to one of three experimental groups: An External Inhibition group, a Graduated Exposure Group, or a Test-Retest Control group.

Following an initial pretreatment assessment, subjects in the External Inhibition group were exposed to the spider in a BAT format, and were presented with an external stimulus (white noise administered in 2-second pulses for 30-seconds at 95dbA) each time they began to feel anxious and stopped the advance of the spider. Graduated Exposure subjects received the same procedure without the external stimulus and were instead instructed to ”relax” themselves whenever they began to feel anxious. Subjects in the Test-Retest group received no intervening procedure and simply sat quietly without the spider present for a comparable period of time.

Dependent measures consisted of pre- and posttreatment BAT scores, subjective distress ratings (SUDS) elicited by the spider, heart rate responding, skin conductance activity, and SPQ scores.

The results failed to provide any evidence of the relative efficacy of external inhibition in modifying phobic behavior. In all cases, the external inhibition treatment was found to be either ineffective or no more effective than the two control procedures in modifying the multiple components of the anxiety response. These findings are discussed in terms of various situational, procedural, and subject factors that may have contributed to the rapid habituation of anxiety among all three experimental groups, and thereby precluded the valid evaluation of potential treatment effects. The implications of these results for the external inhibition phenomenon and for analogue fear research are discussed.


Scanned, with permission from the author, from the original print version, which resides in University Archives.


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