A behavioral validation of the anxiety sensitivity index

08874185/87 53.00 * .oo Copyright D 1987 Pcrgamon Journals. Ltd.

A Behavioral Validation of the Anxiety Sensitivity Index

ROBERTA G. MALLER, M.S. AND STEVEN REISS, PH.D.*

University of Illinois at Chicago

Abstract-The purpose of this study was to validate the Reiss-Epstein-Gursky Anxiety Sensitivity Index (ASI) as a measure of the fear of anxiety. College students were asked to respond to two questions about the experience of anxiety and to two questions about anxiety-irrelevant topics. Mahl’s speech disturbance ratio, a valid and unobtrusive indicator of anxiety, served as the primary dependent measure. Compared with the Low ASI Group, the High ASI Group showed more anxiety to anxiety-relevant than anxiety-irrelevant questions. The findings provide some behavioral evidence of the validity of the ASI as a measure of the fear of anxiety.

Many clients with anxiety and stress-related disorders have been reported to be afraid of experiencing anxiety. This is especially true for clients suffering from agoraphobia, who often are afraid of experiencing panic attacks (Freud, 1895; Goldstein & Chambless, 1978). The fear of anxiety also is especially evident in clients suffering from posttraumatic stress disorder (McNally, Luedke, Besyner, Peterson, Bohm, & Lips, in press). Because the fear of anxiety sometimes is a clinically salient char- acteristic of a client’s problem, clinicians representing the full range of theoretical orientations have suggested the need for serious research at- tention to this phenomenon (Reiss, in press).

Unfortunately, research on the fear of anxiety has been impeded by the absence of a valid technology for measuring this phenomenon. Without a valid measure, researchers cannot scientifically identify subjects who have high versus low fear of anxiety. A first step in any research program on the fear of anxiety should be the development of a valid measure.

The Reiss-Epstein-Gursky Anxiety Sensitivity Index (ASI) repre- sents the final product of three years of exploratory research on various items that might measure the fear of anxiety. The AS1 is a l&item, self- report scale. Each item on the ASI expresses a belief that the experience of anxiety has an undesirable consequence in addition to the immediate unpleasantness of the anxiety sensations. Specifically, AS1 items eval-

* Address correspondence and reprint requests to Dr. Steven Reiss, Department of Psy- chology. University of Illinois at Chicago, P.O. Box 4348, Chicago, IL 60680.

265

‘66 R. G. MALLER AND S. REISS

uate the degree to which the subject believes that anxiety symptoms cause illness (“When I notice that my stomach is upset, I worry that I might be seriously ill”), embarrassment (‘-Other people notice when I feel shaky”), additional anxiety (“It scares me when I feel nauseous”), and a feeling of loss of control (“It is important to me to stay in control of my emotions”). The more anxiety sensitivity beliefs a person endorses. and the more strongly each belief is held, the higher the level of anxiety sensitivity.

The psychometric properties of the AS1 were evaluated in studies reported by Reiss, Peterson, Gursky, and McNally (1986) and by Peterson and Heilbronner (1985). Test/retest reliability over a two-week period has been variously estimated at .75 to .85; Cronbach’s alpha was computed at .88; a single factor structure was obtained in replicated tests with college students. When it is considered that AS1 items refer to a range of imag- ined consequences for anxiety, the degree of internal consistency for the scale was surprisingly high, suggesting that people who tend to endorse one negative implication for anxiety also tend to endorse other negative implications.

The relationship between AS1 scores and psychopathology also has been studied. Two studies have found that agoraphobics score especially high on the AS1 (McNally & Lorenz, in press; Reiss et al., 1986). Clients with posttraumatic stress disorder score about as high as clients with agoraphobia (McNally et al., in press). Clients with other anxiety disorders score significantly lower than agoraphobics but significantly higher than normals (Reiss et al., 1986). AS1 scores are strongly correlated with fearfulness, even after controlling for frequency of anxiety experiences (McNally & Lorenz, in press; Reiss et al., 1986). Holloway’s (1986) recently completed doctoral dissertation found that AS1 scores mediated responses to a hyperventilation challenge test in a manner that supported her three-factor theory of panic.

Perhaps the most challenging part of research on the AS1 was the ef- fort to show that the scale measures something different from that measured by conventionally accepted anxiety scales. All too often, researchers introduce a new scale that is highly correlated with preexisting scales, so that the new scale is essentially superfluous. We hoped to avoid this common problem by showing that the AS1 measures something (the fear of anxiety) that is not measured by preexisting anxiety scales. In other words, we sought to validate the distinction between the fear of anxiety and other phenomena such as the frequency or magnitude of anxiety experiences.

The available evidence consistently indicates that the AS1 is a new measure that is only poorly correlated with conventionally accepted measures of anxiety. For a sample of 147 medical students, the correlation between the AS1 and state and trait anxiety was only .22 and .02, respec- tively (M. Seidenberg, personal communication, September 8, 1986). Reiss et al. (1986), McNally and Lorenz (in press), and Holloway (1986) all found that AS1 scores predict psychological outcomes after partialing

BEHAVIORAL VALIDATION OF ASI ‘67

out the outcome variance explained by conventional measures of anxiety. Furthermore, Peterson and Heilbronner (1985) factor analyzed the AS1 with two measures of anxiety frequency and found that AS1 items loaded mostly on a factor that was independent of anxiety frequency. These findings consistently indicate that the AS1 measures fear of anxiety and that the AS1 is not just another measure for anxiety frequency or anxiety magnitude.

The study reported here was designed to evaluate the validity of the AS1 as a measure of the fear of anxiety. Just as a person who is afraid of snakes should become anxious/fearful when presented with a snake, a person who is afraid of experiencing anxiety should become anxious/ fearful when asked to discuss the symptoms of anxiety. This hypothesis was evaluated by asking college students who scored high and low on the AS1 to talk about what it is like to experience anxiety and to talk about other, anxiety-irrelevant topics. If the High AS1 Subjects were just more anxious than the Low AS1 Subjects, they would show more anxiety in response to both the anxiety-relevant and anxiety-irrelevant questions. If High AS1 Subjects were more afraid of anxiety than Low AS1 Subjects, the differences in anxiety level would be significantly greater for the anxiety-relevant than anxiety-irrelevant topics. In other words, we predicted an interaction between anxiety sensitivity scores and amount of anxiety in reaction to anxiety-relevant versus anxiety-irrelevant stimuli.

METHODS

Subjects

The subjects were 30 college students selected from a sample of 15 1 on the basis of their scores on the ASI. Specifically, the subjects were the 15 highest and 15 lowest scoring students who agreed to participate in the study. The mean anxiety sensitivity scores were 35.1 and 6.3 for the High and Low Anxiety Groups. The subjects participated in the study as one of a number of ways to fulfill a course requirement.

Measures

The primary dependent measure of anxiety was Mahl’s (1956) speech disturbance ratio. This measure reflects the immediate, concurrent level of anxiety and is based on the well-documented tendency of anxiety to interfere with speech and cause dysfluencies. Evidence for the validity of this measure includes correspondence with physiological measures of anxiety (Kasl & Mahl, 1965; Panek & Martin, 1959) and with therapist and teacher ratings of anxiety (Mahl, 1959; Milos & Reiss, 1982).

A portion of the Multiple Affect Adjective Checklist served as the self- report measure of anxiety (Zuckerman, 1960). Specifically, the subjects were given a list of 21 adjectives and asked to check those that applied to

‘68 R. G. MALLER AND S. REISS

their feelings while answering the experimental questions. The list in- cluded the following 11 anxiety-relevant adjectives: nervous, fearful, frightened, panicky, shaky, tense, desperate, terrified, afraid, upset, and worrying. The number of anxiety-relevant adjectives checked served as the measure of anxiety.

Procedure

The first author interviewed all subjects on an individual basis. In order to minimize experimenter bias effects, the first author did not know whether the subject had scored high or low on the anxiety sensitivity scale. The subjects were told that the purpose of the experiment was to study the relationship between attitudes and fears. If the subjects asked additional questions about the purposes of the study. the experimenter stated that she could not say more until the study was over.

The interview consisted of an adaptation question (“Tell me about a movie, book, or television show that you recently enjoyed”) followed by two anxiety-relevant and two anxiety-irrelevant questions. The order of the presentation of the anxiety-relevant and anxiety-irrelevant questions was counterbalanced in order to minimize any possible order effects. In other words, approximately half of the subjects within each group responded first to the two anxiety-relevant questions, and the other subjects responded first to the two anxiety-irrelevant questions. The anxiety-relevant questions were: “What kinds of thoughts and physical sensations do you experience when tense or anxious?” and “How can thosz around you tell when you are tense or nervous, and how do they seem to react?” The anxiety-irrelevant questions were, “What activities do you enjoy in your spare time?” and “What kinds of food do you like to eat’?”

Each interview lasted about 1.5 minutes. The interviews were tape- recorded, and verbatim transcripts were prepared. The first author, who did not know if the transcript being scored belonged to a high or low anxiety sensitivity subject, scored verbatim transcripts for speech disturbances in accordance with Mahl’s (1956) scoring rules. A graduate student, who had been trained to use the same scoring rules, independently scored the responses to 60 randomly-selected, anxiety-relevant questions and 60 randomly-selected, anxiety-irrelevant questions. The interscorer agreement between the first author and the graduate student was high, r = .94.

The adjective checklist was administered twice during the session. once after the two anxiety-relevant questions had been answered, and again after the two anxiety-irrelevant questions had been answered. The subjects were asked to place a checkmark next to any word that de- scribed the way he or she felt while answering the last two questions. The subjects were debriefed at the conclusion of the experimental session.

RESULTS

The hypothesis was that anxiety sensitivity is associated with a tendency for thoughts about anxiety to produce anxiety. The hypothesis

BEHAVIORAL VALIDATION OF ASI 269

permitted the prediction of an interaction effect between subject group and experimental condition. Compared to the subjects in the Low Anx- iety Sensitivity Group, those in the High Anxiety Sensitivity Group were predicted to show a greater increase in anxiety when responding to the anxiety-relevant versus the anxiety-irrelevant questions.

The mean speech disturbance ratios are shown in Table 1. As revealed by an ANOVA, the predicted interaction was statistically significant, F (1,28) = 15.3, p <.OOl. This finding supports the experimental hypothesis. A more detailed examination of the nature of the finding is presented in Table 2. Compared to the Low Anxiety Sensitivity Group, the High Anxiety Sensitivity Group showed higher levels of anxiety to each of the two anxiety-relevant questions. Moreover, the number of speech dysfluencies (numerator in the speech disturbance ratio) was a much more important determinant of the differences in speech disturbance ratios than the number of words spoken (denominator of the ratio). For each of the two anxiety-relevant questions, the High Anxiety Sensitivity Group made significantly more speech dysfluencies than the Low Anx- iety Sensitivity Group, and there were no statistically significant group differences for the number of words spoken, These results provide additional support for the experimental hypothesis.

As shown in Table 1, the adjective checklist scores for self-reported anxiety levels were in the direction predicted by the experimental hypothesis. That is, the increase in anxiety levels from anxiety-irrelevant to anxiety-relevant questions was on average about twice as much for the High Anxiety Sensitivity subjects. However, this result was not statistically significant when evaluated by a blind ANOVA. Nevertheless, some support for the experimental hypothesis is indicated by the findings that, compared to the Low Anxiety Sensitivity Group, the High Anxiety Sen- sitivity Group showed a statistically significant higher level of anxiety when responding to the anxiety-relevant questions, t(28) = 2.5, p < .Ol, but not when responding to the anxiety-irrelevant questions, t(28) = 1.8, ns.

DISCUSSION The study provided behavioral evidence for the validity of the ASI as a

measure of the fear of anxiety. The fear of anxiety was assessed in accor-

TABLE 1 MEAN SCORES ON THE DEPENDENT MEASURES

Experimental Condition

Anxiety-Relevant Anxiety-Irrelevant

Speech Disturbance Ratio x 100 High Anxiety Sensitivity Group Low Anxiety Sensitivity Group

Adjective Checklist High Anxiety Sensitivity Group Low Anxiety Sensitivity Group

11.23 5.65 4.72 5.39

2.27 .a7 .93 .20

270 R. G. MALLER rthiD S. REISS

TABLE 2 MEAT? NUMERATORS. DENOMINATORS, &i~ SPEECH DISTURBANCE RATIOS

High Sensitivity

n = I5

Low Sensitivity

n = 15 F(1.28)

Anxiety-Neutral Questions Question 1

100 x Speech Disturbance Ratio: No. Dysfluencies No. Words

Question 2

6.3 4.3 2.5 I.2

48.6 31.4

1.0 1.8 1.5

100 X Speech Disturbance Ratio: 4.9 6.4 1.1 No. Dysfluencies 2.4 2.0 0.2 No. Words 73.9 32.1 2.5

Anxiety-Relevant Questions Question 3


Question 4

12.9 7.0 10.0”

7.0 3.4 9.4*

64.6 52.7 0.9


10.6 7.8

81.5

6.6 14.8* 2.6 11.6’

67. I 0.6

* Significant dlifcrence between groups at the ,005 level

dance with the same strategy by which any fear might be assessed. For example, if we want to know if a person is afraid of snakes, we can present a snake and observe for a possible fear/anxiety reaction. Simi- larly, if we want to know if a person is afraid of anxiety, we might present anxiety stimuli and observe for a possible fear/anxiety reaction. In this study, we presented anxiety stimuli by asking college students to discuss what it is like to experience anxiety. Relative to a control condition con- sisting of anxiety-irrelevant conversation, the experimental condition of anxiety-relevant conversation produced more anxiety for the High AS1 Subjects than the Low ASI Subjects. This finding suggests that the High AS1 Subjects were more afraid of experiencing anxiety than the Low AS1 Subjects, as was expected under the hypothesis that the ASI is a valid measure of the fear of anxiety.

On first impression, the results of the study might appear to be subject to the alternative explanation of preexisting group differences in anxiety levels. The following argument might be advanced: (a) the High AS1 Sub- jects might have been more anxious than the Low AS1 Subjects; (b) highly anxious people tend to become anxious under many stimulus conditions; (c) therefore, the finding that High ASI Subjects became more anxious when conversing about anxiety might be an example of the tendency of highly anxious people to become anxious under many different stimulus conditions. Under this view, the study would not provide con- vincing evidence that the AS1 is a measure of the fear of anxiety because

BEHAVIORAL VALIDATION OF ASI 271

the data are subject to the alternative explanation that the AS1 is a measure of anxiety.

The alternative explanation should be rejected for three reasons. First, it is conceptually flawed. The concept of anxiety does not imply a tendency for anxiety stimuli to produce anxiety; there is nothing implicit in the concept of anxiety to suggest that conversing about anxiety should produce anxiety. Only the concept of the fear of anxiety, and the closely related concept of anxiety incubation (see Reiss, in press), suggest that anxiety stimuli should produce anxiety. Second, the study controlled for anxiety levels. The High AS1 Subjects showed an anxiety/fear reaction under conditions of anxiety-relevant conversation that was not shown under conditions of anxiety-irrelevant conversation. Thus, it was not the case that the High ASI Subjects had a general tendency to become anxious under conversational conditions but rather that the increase in anxiety/fear level was specific to conversation about anxiety. Third, the alternative explanation is inconsistent with a growing body of evidence of the validity of the ASI. As was summarized in the introduction of this investigation, four different studies, one of which has been replicated four times, all found that the AS1 is not a measure of anxiety frequency or anxiety magnitude (Holloway, 1986; McNally & Lorenz, in press; McNally et al., in press; Reiss et al., in press). Furthermore, preliminary evidence from a sample of 147 medical students suggests that the correla- tions between the AS1 and state and trait anxiety scales are much too low to support the alternative explanation, with rs < .2.5.

Another noteworthy aspect of the methodology of this study is the unobtrusive nature of the speech disturbance measure. For example, the college students probably assumed that the experimenter was interested in the content of their responses to the experimental questions. The students had no basis for suspecting that the experimenter was interested in the rate of speech dysfluencies and was not interested in what was said. Because speech disturbance is an unobtrusive measure of anxiety, we can rule out experimenter demand as an alternative explanation of the results.

In conclusion, the results of this study provide some behavioral evidence for the validity of the AS1 as a measure of the fear of anxiety. If future studies continue to provide favorable results with the ASI, investi- gators might give serious consideration to the use of this measure in studies testing hypotheses about the fear of anxiety.

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Therapy, 9, 47-53. Holloway, W. (1986). Effects of anxiety sensitivity on the response to hyperventilation.

Doctoral dissertation, The University of Health Sciences/The Chicago Medical School. Kasl, S. V., & Mahl, G. F. (1965). The relationship of disturbances and hesitations in spon-

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Mahl, G. F. (1956). Disturbances and silences in the patient’s speech in psychotherapy. Journal of Abnormal and Social Psychology, 53, I- 15.

Mahl, G. F. (1959). Measuring the patient’s anxiety from the “expressive” aspects of his speech. Transactions of the New York Academy of Sciences, 2. 249-257.

McNally, R. J., & Lorenz, M. (1987). Anxiety sensitivity in agoraphobics. Journal ofBe- havior Therapy and Experimental Psychiatry. 18, 3- 11.

McNally, R. J., Luedke, D. L., Besyner, J. L., Peterson, R. A., Bohm, K., & Lips, 0. J. (1987). Sensitivity to stress-relevant stimuli in posttraumatic stress disorder. Journal of

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Miles, M. E., & Reiss, S. (1982). Effects of three play conditions on separation anxiety in young children. Journal of Consulting and Clinical Psychology, 50, 389-395.

Panek, D. M., & Martin, B. (1959). The relationship between speech disturbances in psychotherapy. Journal of Abnormal and Social Psychology, 58, 402-405.

Peterson, R. A., & Heilbronner, R. (1985). The anxiety sensirivify index: Construct validify

and factor analytic sfructure. Paper presented at the 19th annual meeting of the Amer- ican Association for the Advancement of Behavior Therapy, Houston, Texas.

Reiss, S. (in press). Theoretical perspectives on the fear of anxiety. Clinical Psychology

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Reiss, S., Peterson, R. A., Gursky, D. M., & McNally, R. J. (1986). Anxiety sensitivity, anxiety frequency, and the prediction of fearfulness. Behavioar Research and Therapy.

Zuckerman. M. (1960). The development of an affect adjective checklist for the measure- ment of anxiety. Journal of Consulring Psychology, 24, 457-462.

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A behavioral validation of the anxiety sensitivity index