person. in&id. Oifl Vol. II. No. 12. pp. 1213-1219. 1990 Printed in Great Britain. All rights reserved

0191~8869190 53.00 + 0.00 Copyright ,S 1990 Pergamon Press plc

INDIVIDUAL DIFFERENCES IN TYPE A BEHAVIOR AND CARDIOVASCULAR RESPONSES TO STRESS

ANNA GRAY* and DOUGLAS N. JACKSON

apartment of Psychology, University of Western Ontario, London, Ontario, Canada N6A 5C2

(Received 30 December 1987; received/or publication 26 April 1990)

Summary-The purpose of this study was to predict heart rate and blood pressure responses to a stressor task in 166 male and female university students using the multidimensional approach of the Survey of Work Styles. The Survey of Work Styles is comprised of scales for Impatience, Anger, Time Urgency, Work Involvement, Job Dissatisfaction, and Competitiveness. Systolic blood pressure, diastolic blood pressure, and heart rate were measured before and during a 5 min serial subtraction task. Three bipolar Survey of Work Styles profiles were identified for each sex. In males, similarity to each profile was uniquely related to one task cardiovascular measure. In females, two of the three profiles were uniquely related to one physiological measure assessed during the task. The data thus support separate treatment of male and female data. Consideration was given to the possible influence of TABP components, such as Anger, in the differences in the patterns of physiological responses for different Type A profile types. Implications of the physiological results for future studies on psychophysiological differences between Type A and B individuals, and the pathological links between Type A behavior and coronary heart diseases are discussed with emphasis on the recognition of the heterogeneity of personality profiles associated with Type A behavior.

INTRODUCTION

There has been an accumulation of studies demonstrating a relation between psychosocial factors,

especially the Type A behavior pattern (TABP) and coronary heart disease (Jenkins, 1976). The most prominent factor examined has been the Type A behavior pattern (TABP). It has been suggested that Type A behavior increases the risk of coronary heart disease through frequent, intense, and prolonged sympathetic nervous system arousal (e.g. Houston, 1983). This hypothesis has been supported by a number of studies that show that Type A individuals respond to stress with greater physiological changes than Type B individuals. A limitation of these psychophysio- logical experiments is that all studies have used either a continuous approach, where each score represents the person’s relative position with respect to the Type A/B continuum, such that higher scores increasingly reflect the strength of the TABP, or a typological approach to the assessment of the TABP, where the TABP is treated as a dichotomous variable usually obtained by a median split of the data. A multidimensional approach to Type A measurement, such as that used by the Survey of Work Styles (Gray, Jackson & Howard, 1989) characterized by the assessment of individual behaviors and characteristics to yield a profile of the person’s TABP, has yet to be studied. Thus, the major purpose of the research described here is to examine the ability of the Survey of Work Styles to predict individual differences in physiological arousal during a stressful situation.

METHOD

Subjects

A sample of male and female introductory psychology students, each receiving credit in partial fulfillment of the research participation requirement for their class, volunteered for this study. This sample consisted of 79 males and 87 females. The mean age of the Ss was 19.6 yr.

Exploratory data analysis of the baseline physiological responses was conducted separately for males and for females to identify extreme values that might indicate abnormal heart functioning. Outliers were defined as having values exceeding 1.5 interquartile ranges above the 75th percentile

*Present address: Personnel Psychology Centre, Program Development (Staffing), L’Estplanade Laurier, West Tower, 300 Laurier Avenue W., 17th Floor, Ottawa, Ontario, Canada KIA 0M7.

1213

1214 ANNA GRAY and DOWLAS N. JACKSON

or below the 25th percentile. Five male Ss were excluded on this basis from the final physiological analysis.

Measures Cardiovascular measures. Blood pressure and heart rate were measured using a TYCOS model

No. 7052-07 electrosphygmomanometer with visual display. The occluding cuff contained a microphone that was positioned over the brachial artery in the upper portion of the S’s left arm. During the study session, the S was seated at a table facing away from the visual display. Recordings were taken at 2-min intervals during the baseline phase, and at I-min intervals during the stressor task. All data were recorded manually by the researcher. For each physiological variable, a baseline value was calculated as the mean of the last two recordings during the rest phase. Mean task physiological levels were calculated as the mean of all five recordings taken during the task phase.

Assessment of Type A behavior. The TABP was assessed by the Survey of Work Styles, which is a 96 item multidimensional scale consisting of six subscales, (1) Anger, (2) Impatience, (3) Time Urgency, (4) Work Involvement, (5) Job Dissatisfaction, and (6) Competitiveness (Jackson & Mavrogiannis, 1987). The scoring of the Survey of Work Styles consists of summed 5-point weights for positive and negative keyed items for each subscale. A high score on a subscale, therefore, indicates higher frequencies of behavior related to the construct.

Raw scale Survey of Work Styles scores were converted to standard (2) scores in the present study. A cluster analysis procedure as outlined by Jackson et al. (1984), termed modal profile analysis (Skinner, 1977), was then used to cluster respondents into homogeneous groups based on similarity in shape of their Survey of Work Styles profiles.

Procedures

Upon arrival at the test session, the blood pressure cuff was placed over the S’s left arm and an initial measure was taken to demonstrate the physiological recording process and to determine the maximum setting for inflating the cuff. The electrosphygmomanometer was set at 10 mmHg above the first systolic blood pressure recording.

During the baseline phase Ss were instructed simply to sit quietly and rest for 10 min. The serial subtraction task was then presented. Ss were allowed 5 min to complete the serial subtraction task. Following the serial subtraction task, Ss were given the Survey of Work Styles. The .S was then debriefed, thanked and dismissed.

Serial subtraction. The S was instructed to start with a four digit number (1079) and continuously subtract a two digit number (13) from it. He/she was corrected at each mistake. The instructions given encouraged both speed and accuracy of subtraction, as well as emphasizing the 5 min deadline for task completion.

RESULTS

Assessment of the Type A behavior pattern

Modal profile analysis of the Survey of Work Styles yielded three modal profiles. However, analyses conducted separately for each sex showed that these profiles were slightly diffemt for males and females. The three profiles for males and for females are shown in Table 1. The profile scale scores represent deviations from zero within each profile.

The first male and female profiles show the highest scores on Work Involvement and Time Urgency and the lowest scores on Impatience and Competitiveness. The second profiles are characterized by high elevations in Anger and Job Dissatisfaction and by a low Work Involvement score. Although the male and female second profiles are similar, the female profile appears to show greater elevations in Anger and Job Dissatisfaction than does the male profile. The third profiles can be identified by high scores on Impatience and Competitivenes and low scores in Time Urgency and Job Dissatisfaction. In this profile males have a more pronounced depression of the Anger and Job Dissatisfaction components of the TABP. Figures 1 and 2 graphically portray the female and male profiles respectively. It should be noted that these model profiles are bipolar, thus permitting the classification of persons into six types defined by positive or negative scores on each of the three

Cardiovascular responses to stress 1215

Table I. Survey of Work Styles modal profiles of males and females. Values rearesent standard deviations from a mean of 0

Survey of Work Styles subscales

Modal profiles

I 2 3

Males (n = 73) Impatience -0.647 -0.400 0.577 Anger -0.766 0.705 -0.495 Work Involvement 1.753 -0.661 0.996 Time Urgency 0.634 -0.464 -2.001 Job Dissatisfaction 0.236 I.886 0.438 Competitiveness - I.210 - I.065 0.484

Females (n = 86) Impatience -1.092 0.195 0.495 Anger -0.073 I.595 I.100 Work Involvement I.477 -0.853 0.978 Time Urgency 0.849 0.461 -0.720 Job Dissatisfaction 0.203 0.850 - I .749 Competitiveness , - I .364 - 1.325 -0.104

One female S’s data removed because of missing physiological data. Six male S’s data removed because of extreme baseline physiological variables and missing data.

modal profiles. Thus, for the third profile, the negative pole is marked by the mirror image of the positive pole, i.e. by high Time Urgency and Job Dissatisfaction and low Impatience and Competitiveness.

The reliability of the Survey of Work Styles was assessed by computing coefficient r (Cronbach, 1951) for the scales separately for males and females. Unstandardized means, standard deviations, and reliabilities for each sex and the total sample are reported in Table 2. Moderate to high reliabilities were found for the Survey of Work Styles subscales and the Survey of Work Styles total score.

The prediction of physiological responses

To investigate the association between physiological reactions to stress and the TABP as measured by the multidimensional Survey of Work Styles, baseline and mean task blood pressure and heart rate values were correlated with Ss’ loadings on the Survey of Work Styles profiles (Table 1). It was hypothesized that a positive relation would exist between the indices of physiological arousal and the extent to which Ss exhibit the Survey of Work Styles profile.

As observed in Table 3, there is a significant positive correlation in males between mean task systolic blood pressure (r = 0.21, P < 0.05) and Ss’ scores on the first modal profile. A significant positive relation is also found between mean task diastolic blood pressure and Ss’ scores on the second profile (r = 0.23, P c 0.05). Lastly, a reliable positive correlation exists for both baseline

-2

Impatience Anger Work Time Job Competitiveness Involvement Urgency Dissatisfaction

Survey of Work Styles Subscales

Fig. I. Modal profiles of the Survey of Work Styles for 86 female university students. Modal profiles represent typal dimensions.

1216 ANNA GRAY and DCKIGLAS N. JACKSON

z a*

-2

9 $ -3

Impatience Anger Work Time Job Competitiveness Involvement Urgency Dlssatlsfactton

Survey of Work Styles Subscales

Fig. 2. Modal profiles of the Survey of Work Styles for 73 male university students. Modal profiles represent typal dimensions.

heart rate (r = 0.30, P -c 0.005) and mean task heart rate (r < 0.24, P < 0.05), with loadings on the third modal profile. In view of these results, it may be concluded that the pattern of physiological responses in males is influenced by the individual’s Survey of Work Styles profile. Individual differences in the observed physiological levels in response to stress appear to be related to individual differences in the manifestation of the TABP.

The results obtained for females are somewhat different from those obtained for males. Correlational analyses revealed a positive relation between females more strongly displaying the first Type A profile and mean task diastolic blood pressure (r = 0.24, P < 0.05). Mean task systolic blood pressure was positively related to the scores on the second modal profile. The scores on the third modal profile were not related to any task physiological variables, although they were related to baseline diastolic blood pressure (r = 0.25, P < 0.05). While the first female modal profile is almost the same as the first male modal profile, the female profile does not correlate significantly with systolic blood pressure (r = 0.14, P > 0.05) in the female sample. This indicates the importance of sex as a mediator of the relation between the TABP and the physiological responses and suggests strongly that analyses of these variables should be undertaken separately in male and female respondents.

To identify the Survey of Work Styles components that may influence the different cardiovas- cular response patterns among Type A individuals, a principal components factors analysis with varimax rotation was conducted on the Survey of Work Styles subscales for each sex. In both

Table 2. Scale statistics for the Survey of Work Styles. Reliability estimates are Cronbach’s coefficient 2. Mean Competitiveness score is

sianiflcantlv higher for males than for females fP < 0.0005)

I Scale Standard Reliability Scale name mean deviation estimate

Males (n = 79) Total sum 277.04 30.10 0.88 Impatience 48.11 7.40 0.75 Anger 46.09 8.62 0.79 Work Involvement 43.19 9.20 0.79 Time Urgency 46.24 6.77 0.60 Job Dissatisfaction 41.71 7.16 0.73 Competitiveness 50.33 9.81 0.84

Females (n = 85) Total sum 273.56 30.86 0.88 Impatience 47.94 8.39 0.78 Anger 44.90 8.74 0.79 Work Involvement 45.31 9.77 0.82 Time Urgency 48.04 7.45 0.67 Job Dissatisfaction 40.88 7.35 0.76 Competitiveness 45.33 8.3 1 0.78

Two female S’s data removed due to missing responses.

Cardiovascular responses to stress 1217

Table 3. Correlations of baseline and task blood pressure and heart rate with the modal profiles of the Survey of Work Styles. Entries are Pearson Correlation

coefficients

Modal profile

Physiological variables

Males (n = 73) Systolic blood pressure (mmHg)

Baseline Task mean

Diastolic blood pressure (mmHg) Baseline Task mean

Heart rate (bpm) Baseline Task mean

Females (n = 86) Systolic blood pressure (mmHg)

Baseline Task mean

Diastolic blood pressure (mmHg) Baseline Task mean

Heart rate (bpm) Baseline Task mean

*P < 0.05; l *p < 0.005.

I 2 3

0.17 -0.07 -0.08 0.21’ 0.09 -0.04

-0.00 0.05 0.01 -0.05 0.‘)’ _ 0.03

0.18 -0.01 0.30.’ 0.03 -0.01 0.24.

-0.00 0.05 0.06 0.14 0.20* -0.17

0.14 0.02 0.25’ 0.24’ -0.15 0.08

0.02 0.03 0.10 0.05 0.12 0.02

females and males, three factors were identified, accounting respectively for 76 and 75% of the variance. In males, the factors were: (1) Competitiveness/Impatience/Anger, (2) Work Involve- ment/Time Urgency, and (3) Job Dissatisfaction (high Anger). In females the factor were: (1) Anger/Job Dissatisfaction, (2) Competitiveness/Impatience, and (3) Work Involvement/Time Urgency.

The relation of the Survey of Work Styles factors to the Ss’ physiological arousal was examined independently for each sex (see Table 4). A significant positive association for males between Factor 3 and mean task diastolic blood pressure (r = 0.24, P < 0.05) and a negative association between Factor 1 and baseline heart rate (r = -0.27, P < 0.05) were found. The only significant correlation in females was between Factor 3 and mean task heart rate (r = 0.24, P < 0.05).

The increased diastolic blood pressure arousal as measured by the mean task value for the Job Dissatisfaction (high Anger) factor in males is consistent with the increase in task diastolic blood pressure of males strongly exhibiting Profile 2. Both Factor 3 and Profile 2 contain strong expression of the Anger and Job Dissatisfaction components of the TABP, leading to the conclusion that these two components influence diastolic blood pressure. Although the positive correlation between the Work Involvement/Time Urgency factor and mean task systolic blood pressure is not significant (r = 0.13, P > 0.25), the direction of the association is consistent with the positive correlation between Profile 1, that includes strong expression of this factor, and mean task systolic blood pressure. The increase in heart rate during task of those exhibiting the third male profile is not explained by the factors because all factors are negatively correlated with mean task heart rate. Possibly the low Anger and Time Urgency components affect the observed relationship between Profile 3 and task heart rate.

Similarly, the relation between physiological variables and t’le female profiles cannot be easily explained by the correlation between the Survey of Work Styles factors and physiological arousal. Although both Factor 3 and Profile 1 show strong expression of the Work Involvement and Time Urgency components, there is virtually no correlation between Factor 3 and mean task diastolic blood pressure (r = -0.08, P > 0.80). This inconsistency is also evident in Profile 3 and Factor 1 that express the Anger and Job Dissatisfaction components. Although Profile 2 is correlated with mean task systolic blood pressure Factor 1 is not related to this physiological measure (r = - 0.03, P > 0.80). Lastly, Profile 2 is perhaps the most confusing because it does not strongly express any Survey of Work Styles factor completely. This may account for the lack of significant correlations between the expression of this profile and task physiological variables.

1218 Ass~ GRAY and DOLGLAS N. JACKSOX

DISCUSSION

In this study, three distinct bipolar profiles of personal characteristics were found for each sex, indicating the Type A and B populations are not entirely homogenous. There is considerable heterogeneity between individual scores on Type A measures. As shown in this study, it would be erroneous to conclude that all Type A’s exhibit all characteristics considered to be part of the TABP. The major focus of this study, though, was on the relation between the multidimensional assessment of the TABP using the Survey of Work Styles and the physiological responses of Type

A individuals. Each male profile and two of the three female profiles of the Survey of Work Styles components were positively related to a different pattern of physiolgoical arousal. Factor analytic results indicated that the Job Dissatisfaction and Anger components may affect the relationship between the second male profile and diastolic blood pressure. The results for the other two male profiles and the female profiles are not as clear. It is likely that dimensions of the TABP may interact with each other to produce the observed cardiovascular response pattern. These results support the hypothesis that individual differences in cardiovascular responses to a stressor task would be predicted using a multidimensional approach to the assessment of the TABP. Further, the results demonstrate that males and females do not show equivalent physiological response and Type A behavior patterns.

The finding that there are individual differences in the magnitude of cardiovascular responses is consistent with the results of Manuck and Garland (1980) who also found reproducible response differences with respect to heart rate and systolic blood pressure. These researchers hypothesize that these differences reflect individual differences in /.?-adrenergic reactivity. In the same study diastolic blood pressure reactivity did not covary with heart rate or with systolic blood pressure, leading the authors to speculate that diastolic blood pressure reactivity may involve sympathetic influences on peripheral vascular resistance. It seems possible then that certain Type A profiles may differentially affect the sympathetic nervous system resulting in profile differences in cardiovascular reactivity.

The examination of whether or not Type A factors of the Survey of Work Styles are differentially predictive of physiological arousal revealed that the Job Dissatisfaction (high Anger) factor was positively related to mean task diastolic blood pressure in males. The Work Involvement/Time Urgency factor was positively related to mean task heart rate in females. These results are partially supported by past research that has found that hostility and suppression of anger are predictive of basal systolic blood pressure and diastolic blood pressure, and coronary atherosclerosis (e.g. Dembroski, MacDougall, Williams, Haney & Blumenthal, 1985; Johnson, 1984). The importance of job stress and anger in the etiology of coronary heart disease has been noted by Speilberger and London (1982).

How significant are these observed results in identifying the relation between the TABP and coronary heart disease? At present, any significance must be based on the assumption that some components of the TABP are more closely related to certain measures of physiological reactivity

Table 4. Correlations of baseline and task blood pressure and heart rake with factors of the Survey of Work Styles. Entries are Pearson correlation coefficients

Systolic blood Diastolic blood Heart rate pressure (mmHg) pressure (mmHg) (bpm)

Factors Baseline Task Baseline Task Baseline Task

Males (n = 73) Competitiveness/ Impatience!Anger -0.08 -0.17 -0.05 -0.05 -0.25’ -0.17 Work Involvement’ Time Urgency 0. I7 0.13 -0.05 -0.13 -0.02 -0.07 Job Dissatisfaction -0.08 0.04 -0.05 0.24. 0.00 -0.07 (High Anger)

Females (n = 86) Anger/Job Dissatisfaction -0.07 -0.03 0.08 0.07 0.17 0.16 Competitivenessi Impatience 0.05 0.02 -0.06 -0.02 0.00 0.07 Work Involvement, Time Urgency -0.05 -0.03 0.10 0.08 0.20 0.24’

‘P < 0.05.

Cardiovascular responses to stress 1219

than others. Furthermore, the fact that TABP components can be related to different arousal patterns may indicate different pathophysiological processes leading to coronary heart disease (Jenkins, 1978). It is also possible that different TABP components are related to different manifestations of coronary heart disease. Of greater theoretical interest is the finding that the TABP is multidimensional. Perhaps, the inconsistencies obtained in past studies are due to the failure to recognize the multidimensionality of the TABP. Obviously, when all male and female Type A’s are grouped together, overall Type A/B differences in cardiovascular responses may be cancelled out, resulting in the conclusion that Type A and Type B Ss have similar responses to stress. Sex and Type A profile differences must be recognized. In this way, the issue of the relationship between physiological reactivity, coronary heart disease, and the TABP will be best addressed.

Acknowledgemenrs-The authors would like to express their thanks to Sampo V. Paunonen and Warren R. Nielson for their advice. This work was supported by a research grant from the Social Sciences and Humanities Research Council of Canada, and by scholarships from the Medical Research Council of Canada, and the Ontario Graduate Scholarship Program.

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