Document Type

Dissertation

Date of Award

1977

Keywords

Psychophysiology, Autonomic nervous system

Degree Name

Doctor of Philosophy (PhD)

Department

Psychology

First Advisor

Donald J. Levis

Second Advisor

George E. Deane

Third Advisor

Stephen A. Lisman

Abstract

Recent research has shown that individuals scoring low on Barron’s (1953) Ego-Strength Scale show reduced skin conductance and heart rate response to a variety of stimuli. The question as to the manner in which these subjects reduce responsivity remains unanswered. Boudewyns and Levis (1975) have proposed an avoidance model to explain this phenomenon. An experiment based on a design used by Hare and Blevings (1975) was conducted to investigate the possibility that this avoidance takes place at a perceptual level.

Seventy-six female subjects were differentiated into high and low ego strength groups by their scores on Barron’s scale. Utilizing both second by second heart rate and skin conductance responses as monitors of attentional process, stimulus intake or rejection was monitored during a differential classical conditioning procedure using secondary aversive US’s. Subjects were also differentiated according to their self-reported fear level to the secondary aversive slide material (slides depicting bodily injury) such that the interaction of subject fear and ego-strength could be evaluated. Half of the subjects reporting high fear received specifically unpaired presentations of the tone CS's and slide US's in order to separate associative effects from non-associative effects due to the conditioning procedure. Prior to conditioning trials, all subjects underwent a balloon stressor test to test for possible autonomic system differences between the high and low ego-strength subjects. Following conditioning trials, subjects received reaction time trials to the tone CS’s to investigate the acquisition of drive properties by the tones due to pairing the tones with the aversive material. During the final phase of the experiment, the subjects were given a fear test to the slides used during the conditioning phase of the experiment. During this test, subjects were asked to view the slides as long as they felt comfortable doing so.

The results of the experiment showed that the high and low ego-strength subjects did not differ in direction of attention during the tone signals preceding the aversive slide material. Additionally, high and low fear subjects failed to show differential conditioning of the OR and DR as had been demonstrated by Hare and Blevings (1975). Comparisons of groups receiving the paired and unpaired conditions showed no difference in response, suggesting the Hare and Blevings (1975) findings were due to non-associative effects.

Consistent with previous literature, subjects in the low ego-strength groups showed diminished responsivity in both heart rate and skin conductance channels. This effect developed as a function of increased trials, suggesting that the low ego-strength subjects were selectively applying defenses designed to reduce autonomic responsivity. Data available suggest that the reduced responsivity was not due to habituation. Although larger skin conductance responses were shown to the bodily injury than to the neutral slides, there were no differences in response magnitude between the high and low fear groups to these materials.

As with response to tone or slide material, low ego-strength subjects also showed less skin conductance response during the balloon test. These data differ from data presented by Boudewyns and Levis (1975) who failed to find ego-strength differences to a balloon stress test. The results of the present experiment suggest that autonomic nervous system differences may exist between high and low ego-strength subjects.

Analysis of tone reaction time data revealed that the pairing of the tone and slide stimuli did not produce faster reaction times to the tones. Thus, secondary drive properties were not acquired by the tones.

Slide viewing latencies showed that high fear subjects viewed the bodily injury slides less time than subjects reporting low fear of this material. Comparison of groups receiving paired and unpaired presentations of the slide material prior to the fear test revealed that unsignaled presentation of slides produced longer viewing times to these materials. These data suggested that, consistent with avoidance theory, signaling a secondary aversive stimulus minimizes the amount of habituation to that stimulus.

These data were discussed in the context of the available literature and the relation of the data to a developmental theory of ego-strength. As discussed by Boudewyns and Levis (1975), low ego-strength appears to be related to a subject’s tendency to avoid physiological arousal.

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