International Journal of Psychophysiology, 13 (1992) 101-110
101
© 1992 Elsevier Science Publishers B.V. All rights reserved 0167-8760/92/$05.00 INTPSY 00402
Social interaction, cardiovascular activation and the Type A behavior pattern T h o m a s Palm a and A r n e t ) h m a n b Department of Rehabilitation Medicine, Karolinska Hospital (Sweden) and b Department of Clinical Psychology, Unicersity of Uppsala, Uppsala (Sweden) (Accepted 4 June 1992)
Ke3' words: Social interaction; Psychophysiological reactivity; Coronary prone behavior
The purpose of the study was to explore the relationship between social interaction and cardiovascular activity during a conflict-inducingcommunication task in Type A and B subjects. One of the subjects, the leader, was instructed to lead the other subject, the follower, through defined routes on a c;ty map merely by help of instructions. The subjects were facing each other on each side of a screen which allowed eye contact but shielded the maps from view. 40 male students (mean age 24 years) exhibiting Type A or Type B behavior according to the Videotaped Structured Interview participated in the study. The results demonstrated large cardiovascular increases during task performance, particularly for leaders, in systolic blood pressure and heart rate. There were no main effects of Type A vs. Type B, but dyads composed of two Type As showed larger increase in diastolic blood pressure during the conflict phase of the task compared to dyads composed of Type Bs.
INTRODUCTION Evolution has shaped humans to be highly responsive to social events and stimuli (Ohman and Dimberg, 1984). However, psychophysiological research typically deals with responses to nonsocial situations, presumably because they are easier to control and manipulate experimentally. 0 h m a n and Dimberg (1984) pointed out that this practice puts investigators at the risk of missing evolutionary shaped behavior tendencies that may be most likely to generate ubiquitous physiological responding. Research on 'stress' may be taken as a case in point. In the laboratory, stress is induced, for example, by exposure to aversive stimuli, such as the cold-pressor test, by task performance under
Correspondence to: A. Ohman, Department of Clinical Psychology. University of Uppsala, Box 1225, 751 42 Sweden.
threat of shock, or perceptual conflicts such as in the Stroop color naming task. In real life, however, socially induced stress is probably much more prevalent and intense than stress due to exposure to aversive stimuli. When failing in task performance, it is not the failure per se that is most stress-inducing, but its social consequences in terms of criticism or 'lost face' in front of others. To capture these aspects of stress, it is necessary to use social experimental situations. Blakar (1980, 1984) has developed a promising experimental situation promoting what appears spontaneous social interaction under reasonably controlled conditions. This situation incorporates a central dimension of potentially stressful social interaction, that of dominance. Thus, one of the persons in the interacting dyad, the leader, is required to take a dominant role in symbolically guiding his partner, the follower, through the center of a city by help of a map. Each participant is faced with allegedly identical maps, which
102 are shielded from view by the partner. However, at a critical point, the maps do not match. As a consequence the follower gets lost, which sets the stage for dominance conflicts. Blakar (1980, 1984) used this task to study communication in families having a disturbed member, such as a schizophrenic child. His results indicated that individuals differ markedly in ways of coping with the communicative conflict. Thus, an interactional perspective, taking account of both individual and situational factors (l~hman and Magnusson, 1987) is called for in analysing the effects of the task. A potentially crucial concept of individual differences in this context is that of Type A behavior, because social dominance is one of its most important components (e.g., Straub et al., 1990). Furthermore, Thoresen and 0hman (1987) argued that analyses of this behavior pattern must consider the interaction between social situational conditions and characteristics of the person. Thus, it appears especially important to relate physiological reactivity among Type As to different social contexts. The overwhelming majority of Type A research, however, has been concerned with solitary task performance, and little attention has been paid to dyadic or group interaction. An exception is provided through a study reported by Abbott et al. (1987). They explored the relationship between behavior pattern and cardiovascular events when Type A and Type B subjects cooperated in dyads, and reported larger cardiovascular responses in Type As cooperating with other Type As than with Ty?e Bs. Similarly, Glass et al. (1980) showed that an overtly hostile opponent resulted in larger cardiovascular responses in Type As than in Type B subjects during a video game. Finally, VanEgeren and colleagues (I979a, b) have reported data from studies of social interaction in Type As and Bs. Their findings indicated (VanEgeren, 1979a, b; VanEgeren et al., 1982; VanEgeren et al., 1983a, b) that Type A individuals tended to be more aggressive, competitive and dominating than Type Bs. In some experiments, but not all, Type A showed larger heart rate and digital vasoconstriction responses, as well as cardiac arrhythmias, and ST segment depression. Any particular cardiovascular re-
sponse did not differentiate Type As and Bs in all experiments, but when it did, Type As were always more reactive than Type Bs. These studies indicate that differences in reactivity between Type As and Type Bs emerge when subjects are confronted with social situations engendering competition for dominance. The purpose of the present study was, firstly, to examine physiological correlates of the roles as leader and follower in the Biakar Communication Conflict Task. Secondly, we explored the relationship between the Type A behavior pattern and cardiovascular events during social interaction in this task. Thus, we examined physiological reactivity (SBP, DBP, HR), and subjective arousal in Type A and Type B individuals serving as leaders/followers, and interacting with partners of the same or the opposite category.
METHOD
Subjects The selection of subjects followed a two-step procedure. The first step used the Type A SelfReport Inventory (TASRI) (Blumenthal et al., 1985). A total of 320 law and economy students (113 males) answered the TASRI. In the second step, male subjects were invited to participate in a videotaped structured interview (VSI) (Friedman and Powell, 1984; Ohman et al., 1992) to diagnose Type A behavior, in descending order for subjects with high TASRI scores, and in ascending order for subjects with low scores, until 40 subjects had been recruited. The VSI is scored on the basis of observed signs of Type A behavior in gestures, speech and content. The derived scale of Type A behavior show good internal consistency, and good agreement between judges (intraclass 0.764), and adequate stability over time (r -- 0.65 for a 2 year period) (see Ohman et al., 1992). Swedish judges also show high interrater agreement with a judge from the Meyer Friedman Institute in San Francisco. Half of the recruited subjects were law students and the other half economy students. The age range was 20 to 30 years (mean -- 24 years). For VSI, total scores larger than or equal to a
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cutoff of 80 defined the Type A group and scores less than or equal to 69 defined the Type B group. Half of the subjects within each of the student categories were classified as Type A (n -20, mean = 95.1, S.D.-- 11.9) and the other half as Type B (n = 20, mean = 60.0, S.D. = 9.7) according to the VSI. One of the subjects (Type B) was on blood pressure medication. Each subject received $5.00 for taking part in the interview and $10.00 for the experiment. After the interview all participants completed two questionnaires, the Jenkins Activity Survey and the Heart and Lifestyle Type A Measure. However, results from these questionnaires will not be reported in this paper.
Apparatus and recording methods Two disposable 14 mm diameter HP-ECG electrodes were positioned bilaterally and precordially on the chest for optimal R-wave signal; the ground electrode was placed on the left shoulder.
The ECG signals were transduced and filtered throw a HP 8811 A amplifier. A Hewlett-Packard 7754-A four-channel polygraph displayed signals on paper from both subjects simultaneousbj. Paper speed was set to 2.5 mm/s. Heart rate (HR) was continuously recorded during rest and the experimental routes. Systolic and diastolic blood pressure (SBP and DBP, respectively) were measured with two laboratory-built automated blood pressure systems, utilizing the auscultatory method. The systems have been validated against intraarterial recordings with high correlations for SBP (0.97) and for DBP (0.81) (Eiiasson et al., 1983). The cuffs were placed on the subject's upper left arm if they were right handed, if lefthanded, placement was reversed. A microphone detecting the Korotkoff sounds was placed over the brachial artery. Cuff pressure and Korotkc,ff sounds were displayed on the polygraph. The pressures associated with the appearances (Phase I) and attenuation (Phase IV) of Korotkoff sounds
Leaders Map Followers Map
\
\
Fig. 1. The communicative situation with the conflict inducing manipulation (extra street) marked. The leader and follower's version of the map are shown left and right, respectively.
104 were recorded as systolic and diastolic blood pressure respectively, approximately once per minute during rest and task.
Procedure Subjects were seated in the laboratory and were told to sit quiet and relax during the initial rest period. The participants (Leader and Follower), sat at opposite ends of a table (1.5 × 1.5 m). The placement of Leaders and Followers were always the same. To ensure that subjects in the interacting dyads did not know each other, each dyad had one member from the law, and one from the economy student population. The subjects were facing each other on each side of a screen (40 cm in height) which allowed natural eye-contact but shielded the maps which were placed on the table in front of the subjects. The subjects were instructed (see Blakar, 1980, 1984), that one of the subjects, the Leader, was to lead the other subject, the Follower, through defined routes on a city map (see Fig. 1) by help of instructions. Two routes were marked with arrows on the Leader's map, one short and straightforward (1st route, the simple situation), and another longer and more complicated (3rd route, the conflict situation). No route were marked on the Followers map. The Leaders task was to explain the two routes to the Follower. The Follower then, had to try to find his way through the town. He was allowed to ask questions, for example, ask the Leader to repeat the explanations. The experimental manipulation was simply that the two maps were p,~t identical (see Fig. 1). An extra street was added on the Followers map. Thus, no matter how adequately the Leader explained or the Follower carried out the instructions, the Follower was still bound to go wrong. However~ the discrepancy between the two maps affected only the complicated 3rd (experimental) route. A pilot study on seven men and women with the original version of the experimental situation (Blakar, 1980, 1984) prompted the following modification: to promote confidence in the procedure, an extra map-route, the 2nd route was added. It had the same extension as the 3rd route, but did not involve any discrepancy be-
tween maps. In adding the second route, the idea was to enhance the feeling of 'a shared social reality" which would potentiate the (subjective and physiological) effects when communication failed during the 3rd route. In the instruction, time pressure was added because of its conceptual relevance for Type A behavior. The 1st route was merely for practice in the task and included no time pressure or physiological recording. The 2nd route and 3rd route were time-limited. Time-limit was 5 min. Time pressure was emphasized by a visible digital clock which showed min, s and 1/10 s. The clock was started when the experimental routes begun. Furthermore, the experimenter (a male) announced the elapsed time loudly at half minute intervals. The subjects were told that physiological activity would be recorded simultaneously and continuously throughout the 2nd and 3rd route but that the 1st route was only for practicing and no measure of any kind was taken. Self ratings. To assess experienced arousal during rest and the two routes with social interaction, an adjective checklist was administered. It consisted of items from four factors: energy, stress, irritability and task involvement. The relevance of these factors for phenomenological arousal has been documented by Bohlin and Kjellberg (1973) and Kjellberg and Bohlin (1974). The rating sheets were administered after rest, and after the 2nd and the 3rd routes. The subjects were told to retrospectively rate their mood as felt under the preceding task, and not to reflect on their current feelings.
Design and statistical analyses Scoring of cardiovascular data. Only results from the 3rd route were of interest and are presented here. The task lasted for a maximum of 5 min. Pre-conflict, conflict and post-conflict period means were based on two measurements. The post-conflict, that is, the recovery value, was based on the last measurement or the value that followed immediately after con~qict solution. The pre-conflict period mean value was based on measurement at onset and after 30 s of Task performance. The conflict period mean value was based on one measurement beginning with the
105
first unequivocal indication that the follower was lost and another measurement one minute later. Baseline values were collected and averaged during the three last minutes of the initial rest period. Heart-rate was scored by counting the number of successive R-waves occurring during a 20 s period ( × 3 in the analysis), beginning with the measurement of blood pressure onset. The basic experimental design was a 2 Behavior-Pattern (Type A and Type B) × 2 Function (leader and follower) × 3 Taskperiod (pre-confilet, conflict and post-conflict). Behavior Pattern and Function were between-subject factors and Taskperiod was a within-subjects factor. To test the importance of group composition, a two-factor dyad between groups design (A_A, AB, BA and BB, the first letter in dyads denotes the leader), with repeated measures (pre-conflict, conflict and post-conflict)was used. The effects examined in this set of analyses included the main effect of Group and the interaction between Group and period. All effects were tested by analysis of covariance (SAS, 1985) using the appropriate baseline (rest values or rest ratings) as the covariate. The probability value (0.05) associated with the Greenhouse-Geisser correction procedure for repeated measures (GreenhouseGeisser, 1959) was used, because of possible violations of the sphericity assumption. Tukey's Honestly Significance Difference (HSD) test were conducted post-hoc, on adjusted means, to identify significant differences where appropriate. Self-rating. Each arousal factor (Energy, Stress, Interest and Irritability) was Separately analyzed according to the same basic experimental designs as for cardiovascular data but without repeated measures.
TABLE I Baseline means for Type A / B Leaders / Followers Standard deviations in parenthesis
Type A Type B
L F L F
SBP
DBP
HR
115.4 (12,8) 114.7 (8,2) 115.2 (12.5) 122.6 (7.0)
71.3 (6.8) 67.4 (9.1) 69.4 (7.4) 66.1 (9.8)
70,5 (7.4) 75,0 (10,1) 69.2 (9,9) 74,6(11.1)
Thus, during social interaction the Leaders were about 20 mmHg above the followers which generated a highly significant main effect for Function (F(1/35) = 27.03, P < 0.001) in the ANCOVA, and this difference was apparent throughout the three task periods. No significant effect due to Behavior-Pattern was revealed. A within-subjects main effect of task period ( F ( 2 / 7 0 ) - 4.05, P < 0.05) appeared, which primarily was attributable to a decrease in SBP after the conflict period. ~/B L/F
~ TYPE A TYPE B
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1;32 D. rn 128
124
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RESULTS
Cardiovascular effects SBP. No significant differences were obtained at baselines for Behavior-Pattern and Function (see Table I). However, the leaders showed a dramatic increase in SBP during task performance whereas the followers showed little change (see Fig. 2).
1£6
REST
BEFORE
DURZNG
AFTER
Fig. 2. Systolic blood pressure in a conflict inducing communicative task for type A and B persons holding a role as leader (L) and follower (F), respectively. Task period means, preconflict (Before), conflict (During) and post-conflict (After) are corrected for baseline (rest) levels.
106 RiB
TABLE 1I
Cardiovascular effects for interacting dyads during the communication conflict period Dyads AA AB BA BB
rnmHg I
ss ,',-
DBP
HR
131.0 (4.3) 131.0 (4.3) 129.0 (4.3) 127.0 (4.3)
88.3 (2.7) 80.8 (2.7) 78.8 (2.7) 79.0 (2.7)
78,8 (2.1) 81.0 (2.1) 82.5 (2.1) 79.9 (2.1)
__ T Y P E
A
~- T Y P E
B
..! t
Adjusted means (S.E. in parentheses) SBP
L/F
B8f
//
O't-t !
To examine differences between dyads across periods, a 4 x 3 ANCOVA was performed. It generated a significant Dyad × Taskperiod interaction (F(6/70) = 2.45, P < 0.05). The interaction suggested differential dyad responding over taskperiods. However, as shown in Table II, the groups were not different during the conflict part of the task. Thus, post-hoc analyses showed that the effect could be attributed to differential developments after the conflict when dyad BA significantly increased their SBP levels, compared to the other dyads, who recovered their responses. DBP. The analysis for DBP showed no differences in baseline (see Table I) and the ANCOVA gave no significant between-subjects effect for Behavior-Pattern or Function, but a main effect of Taskperiod (F(2/70) = 5.07, P < 0.05). The latter effect was due to an overall increase from pre-conflict to conflict, and then a decline in activity (see Fig. 3). The analysis of Dyads revealed no significant between-subjects effect but a significant Dyad × Taskperiod interaction (F(6/70) = 2.34, P < 0.05). Tukey tests revealed (see Table !I) that the
,:/
",\
,
,/
/ /
74
/
/ /
//
/
"-.,
/ f"
I //
REST
BEFORE
DURZNG
DBP in dyad AA was significantly higher than that of groups BB and BA during the conflict. Group AB was slightly above the latter two groups, but it was just significantly below the AA group. HR. Although the leaders tended to have somewhat lower baselines than followers (see Table I), the differences were not significant. The
Self-rating effects for Type A / B Leaders and Followers Adjusted means (S.E. in parentheses) mean rest
Energy Stress Interest Irritability
24.3 13.9 12.5 6.1
RFTER
Fig. 3. Diastolic blood pressure in a conflict inducing communicative task for type A and B persons holding a role as leader (L) and follower (F), respectively. Task period means, oreconflict (Before), conflict (during) and post-conflict (After), are corrected for baseline (rest) levels.
TABLE !11
Factors
,~
Type A
Type B
L
F
L
F
30.5 (0.97) 21.4 (!.7) 12.5 (0.47) 8.9 (0.97)
30.6 (0.97) 20.8 (i.7) 12.9 (0.48) 9.8 (0.99)
29.4 (0.96) 19.6 (I.7) 12.5 (0.48) 8.2 (0.93)
29.9 (0.96) 21.1 (1.7) 12.,3 (0.47) 8.4 (0.93)
107 R/B
L/F
~
HR
;
TYPE R
~" T Y P E B
92 L
L
Self-rating effects The results of self-rating effects in the arousal factors for Type A / B leaders and followers are summarized in Table III. Effects of Function or Behavior-Pattern were not significant in any of the factors.
DISCUSSION
,Be p--
p
f
,,] / .i
.+ .+]i // "
F
i/,,
r //// r ill
REST
6EFORE
DURZNG
RFTER
Fig. 4. Heart rate in a conflict inducing communicative task for type A and B persons holding a role as leader (L) and follower (F), respectively. Task period means, pre-conflict (Before), conflict (during) and post-conflict (After), are corrected for baseline (rest) levels.
HR ANCOVA generated a significant between main effect for Function, ( F ( 1 / 3 5 ) = 10.46, P < 0.01), and a Function × Behavior-Pattern interaction ( F ( 1 / 3 5 ) = 3.83, P = 0.05). The interaction could be attributed to a larger difference between leader and followers among Type Bs than among Type As (see Fig. 4). No significant main effect was due to Behavior-Pattern. A within subject interaction between Task period and Function ( F ( 2 / 7 0 ) = 3.7, P < 0.05) suggests different changes in activity over taskpe~'iods for leaders and followers. Post-hoc analyses revealed significant differences between leaders and followers before and during the conflict, but the decrease in activity was more pronounced among the leaders than for followers after the conflict. Two way analyses of dyads revealed no significant effects (see Table II).
The present results demonstrated large increases in cardiovascular activation during social interaction and interpersonal conflict in subjects assigned the role of guiding another subject through a task. These effects were particularly obvious for SBP, which produced change from baseline of about 22 mmHg, independently of behavior pattern. Thus, for this measure the role or the position in the social interaction proved a potent factor in determining cardiovascular reactivity. For DBP, however, there was no reliable effect associated with the position of leader. The overall increases in SBP, HR and partly in DBP deafly suggest enhanced sympathetic load on the cardiovascular system during social interaction. For subjective arousal there were no significant effects but a tendency for the factors Energy and Stress to change from baseline to task (see Table III). The fact that clearcut changes were observed in SBP and HA, but not in DBP, may be taken to suggest that the cardiovascular effects reflected an increased fl-adrenergic effect on the myocardium rather than an a-adrenergic effect on the peripheral vascular bed. To be leader in social interaction under time pressure, therefore, appears very effective in prompting cardiovascular activation. There were no significant main effects of behavior pattern, but when looking at dyadic interaction during the conflict, Type As were s;gnificantly more reactive in DBP (of about 8 mmHg) when they interacted with another Type A, than when two Type Bs interacted with each other. These data are similar to those reported by VanEgeren et al. (1979a) in that they suggest that stress-induced reactivity is particularly obvious when two Type As interact socially. A number of
108
studies (Diamond et al., 1984; Smith et al., 1984; Dembroski et al., 1977). reported sympathetically mediated effects in cardiovascular parameters such as SBP and HR to different forms of challenges, but minimal changes in DBP for Type As. From the conclusions reached by VanEgeren (1978) it is tempting to speculate about Type A, aggression, and interpersonal disagreement. VanEgeren found anger expression to be uniquely related to diastolic changes. The more the subjects expressed anger, the lower were their DBP levels. During this study all the dyads exhibited low overt interpersonal antagonism and there were few signs of overt anger during interactions, and in general the subjects reported low levels of irritability, see Table Ill (max 25). Yet from VanEgeren's (1978) findings, the DBP data in this study may be taken as indicating considerable covert anger and irritation, particularly when Type As interacted with each other. Further support for an interpretation of DBP as related to anger comes from the literature on the psychophysiology of emotion. Thus, Roberts and Weerts (1982) reported change in diastolic blood pressure to be significantly greater for high anger than for high fear during mental imagery. Furthermore, Ax (1953), found support for specificity in physiological response patterns in that an anger producing situation resulted in rises in DBP and declines in HR, a different pattern compared to the fear situation, which primarily resulted in elevated SBP and HR. For HR, there was a reliable interaction between Function and Pehavior Pattern to the effect that the roles as Leader and Follower were much more clearly separated among Type B than among Type A individuals (see Fig. 4). Thus, Type B leaders were above Type A leaders, and Type B followers were below Type A followers. Assuming that Type As are more dominant than Type Bs (e.g., Straub et al., 1990), one interpretation of this finding is that it is particularly stressful to enact an incompatible role, thus resulting in elevated HR levels. Whereas Type A leaders simply foUowed their inclination towards dominance, Type B leaders had to act in opposition to their tendencies toward submissiveness when fulfilling their role in the social interaction. Simi-
lady, Type A followers may have been provoked by being placed in a situation where they had to yield to a person they perceived as less dominant than themselves. This interpretation is in line with the findings by Straub et al. (1990) who found evidence for more dominance in Type A males and females than for their respective Type B counterparts in a competition paradigm. The effect of speech on blood pressure provides a potential confounding factor in the attribution of our results to social interaction factors such as dominance. Lynch (1985) demonstrated a dynamic relationship between speech and BP reactivity. As the subject talked, there was a concomitant rise in blood pressure, and the increase was related to formal characteristics of the speech. Similar data were reported by Smith and Allred (1989), who examined cardiovascular reactivity during speaking and listening to a partner, in a debate format. They found that their subjects had higher SBP (4 mmHg), DBP (7 mmHg) and RR (7 bpm) when they spoke than when they listened. In the present study it is likely that the leaders talked more than the followers, because of their dominant role in the interaction. This difference in speech activity, in turn, may have prompted heightened SBP and also HR. However, the effects of speech on bioodpressure, reported by Lynch (1985) and Smith and Allred (1989), are unlikely to provide a complete account of our findings. In general, the effects of speaking reported by Smith and Allred (1989) were small compared to the effect of social position in our study (e.g., for SBP, 4 mmHg vs. 22 mmHg). Furthermore, they examined differences between listening and speaking conditions. In our study, however, both leaders and followers spoke, and sometimes the follower was verbally more active than the leader. Feldstein and Welkowitz (1978) suggested that participants in dyadic interactions tended to match each others voice style, for example, with regard to intensity. According to Siegman et al. (1990)cardiovascular reactions tend also to match in partners engaged in social interactions. Thus, the cardiovascular effects may not exclusively be explained by speech-related reactivity, but may also reflect different social comparison processes. In accordance with this
I09
conclusion, Henderson et al. (1990) found that HR could not be accounted for in terms of speech associated cardiovascular changes, but appeared to be most sensitive to situational demands. Finally, Linden (1987) found that the emotional significance of the speech content was more important for autonomous activation than was the speech act per se. Thus, in conclusion it appears that social, situational and emotional factors have effects on blood pressure above what could be expected from the simple act of speaking per se. From the shapes of the curves in Figs. 2, 3 and 4, it appears that the cardiovascular activity increased abruptly with the start of the task, and that there was minimal further increase during the conflict phase of the task. The reason for this might be that the conflict-inducing situation was too simple and easy to solve. Some of the dyads solved the conflict situation, i.e., they identified the critical point, settled the disagreement, and chose a new strategy. This is in marked contrast to the reports of Blaker (1980, 1984), which suggested that most of his subjee*~ ~ot stuck in the conflict. However, the present subject population was students, who may be expected to use their high verbal and communicative skills to help solving the conflict. The participants quickly attributed the verbal disagreement to the maps, realizing that they were not identical. Often they also identified the critical point. Thus, they handled the potential conflict in an efficient, functional, and non-emotional manner. Another reason for not overtly showing anger might have been that the subjects were unknown to each other, which might have inhibited overt signs of anger. It is likely that the odds of eliciting hostility would be better if the subjects in a dyad know each other well, for example if they were spouses. Given the intrinsic interest of the task for the subjects, it is likely that it would be quite arousing even without the use of different maps for leaders and followers. It may be more effective to manipulate intrinsic aspects of the task, such as its complexity, or perhaps, the time available to complete the task. By omitting map discrepancy, the task could be replicated several times, enhancing its reliability, and allowing, e.g., measurement of change after interventions. Thus, there
are several ways that the present experimental situation can be improved as a method to elicit cardiovascular reactivity in an ecologically meaningful way.
ACKNOWLEDGEMENTS This investigation was supported by grants from the Bank of Sweden Tercentenary Foundation and from the Swedish Council for the Humanities and Social Sciences to the second author. The authors would like to thank Gunilla Bohlin for helpful advice in preparing the study and Kristina Stjernl6f for conducting all Type A interviews.
REFERENCES Abbot, J., Sutherland, C. and Watt, D. (1987) Cooperative dyadic interactions, perceived control, and task difficulty in type A and type B individuals: A cardiovascular study. Psychophysiology, 24: 1-13. Ax, A.F. (1953) The physiological differentiation between anger and fear in humans. Psychosom. Med. 15: 433-442. Blakar, R.M. (1980) Studies of familial communication and Psychopathology, Oslo, Norway, Universitetsforlaget. Blakar, R.M. (1984) ComMunication: A social perspect;.ve on clinical issues, Oslo, Norway, Universitetsforlaget. Blumenthal, J.A., Herman, S., O'Toole, L.C., Haney, T.H, Williams, R.B. and Barefoot, J.C. (1985) Development of a brief self-report measure of the type A behavior pattern. J. Psychosom. Res., 28: 265-274. Bohlin, G. and Kjellberg, A. (1973) Self reported arousal during sleep deprivation and its relation to performance and physiological variables. Scand. J. Psychol., 14: 78-86. Dembroski, T.M., MacDougall, J.M. and Shields, J.L. (1977) Physiologic reactions to social challenge in persons evidencing the type A behavior pattern. J. Hum. Stress, 3: 2-10. Diamond, E.L., Schneiderman, N., Schwartz, D., Smith, J. C., Vorp, R. and Pasin, R.D. (1984) Harassment, hostility and type A as determinants of cardiovascular reactivity during competition. J. Behav. Med., 7: 171-189, Eliasson, K. Hjelmdahl, P. and Kahan, T. (1983) Circulatory and sympatho-adrenal responses to stress in borderline and established hypertension. J. Hypertens. 1: 131-139. Feldstein, S. and Welkowitz, J. (1978) A chronography of conversation: In defense of an objective approach. In A.W. Siegman and S. Feldstein (Eds.), Nonverbal behavior and communication, 2nd Ed., Hillsdale, Earlbaum. Friedman, M. and Powell, L. (1984) The diagnosis and quantitative assessment of Type A behavior: Introduction and
110 description of the Videotaped Structured Interview. In. tegr. Psych., 2: 123-136. Glass, D.C., Krakoff, L.R., Contrada, R., Hilton, W. F., Kehoe, K., Mannucci, E.G., Collins, C., Snow, B. and Elting, E. (1980) Effect of harassment and competition upon cardiovascular and plasma catecholamine responses in type A and B individuals. Psychophysiology, 17: 453-463. Greenhouse, S.W. and Geisser, S. (1959) On methods in analyses of profile data, Psychometrika, 24: 95-112. Henderson, R.P., Bakal, D.A. and Dunn, B.E. (1990) Cardiovascular response patterns and speech: A study of air traffic controllers. Psychosom. Med., 52: 27-41. Kjeilberg, A. and Bohlin, G. (1974) Self-reported arousal: further development of a multi-factorial inventory. Scand. J. Psychol., 15: 285-292. Linden, W. (1987) A microanalysis of autonomic activity during human speech. Psychosom. Med., 49: 562-578. Lynch, J.J. (1985) The language of the heart: The body's reslmnse to human dialogue, Basic Books, New York. Ohman, A., Burell, G., Ramund, B. and Fleischman, N. (1992) Decomposing Coronary-Prone Behavior: Dimensions of Type A behavior in the Videotaped Structured Interview. J. Psychopathol. Behat'. Assess, 14: 1-33. Ohman, A. and Dimberg, U. (1984) .~'a evolutionary perspective on human social behavior. In W.M. Waid (Ed.), Sociophysiology, Springer, New York~ pp. 47-86. Ohman, A. and Magnusson, D, (1987) An international paradigm for.research on psychopathology. In D. Magnusson and A. Ohman (Eds.), Psychopathology: An interactional gerspective, Academic Press, New York. Roberts, R. and Weerts, T. (1982) Cardiovascular responding during anger and fear imagery. Psychol. Rep., 50: 219-230. SAS User's Guide (1985) Statistics, Version 5 Edition, SAS Institute Inc., Cary. Siegman, A.W., Anderson, R.A. and Berger, T. (1990) The angry voice: Its effects on the experieace of anger and cardiovascular reactivity. Psychosom. Med., 52: 631-643.
Smith, T.W., Houston, B,K. and Stocky, R.J. (1984) Type A behavior, irritability, cardiovascular response. Motit'. Erupt., 8: 221-230. Smith, T.W. and Allred, K.D. (1989) Blood pressure Responses During Social Interaction in High and Low Cynically Hostile Males, J. Behat:. Med., 12: 135-143. Straub, R.O., Grunberg, N.E., Street, S.W. and Singer, J.E. (1990) Dominance: Another facet of Type A, ]. Appl. Soc. Psychol.. 20: 1051-1062. Thoresen, C.E. and Ohman, A. (1987) The Type A behavior pattern: A person-environment interaction perspective. In D. Magnusson and A. Ohman (Eds.), Psychopathology: An interactional perspectire, Academic Press, New York, pp. 325-346. VanEgeren, L.F., Abelson, J.L. and Thornton, D.W. (1978) Cardiovascular consequences of expressing anger in mutually dependent relationship. J. Psychosom. Res., 22: 537548. VanEgeren, L.F. (1979a) Social interactions, communications and the coronary-prone behavior pattern: A psychophysiological study. Psychosom. Med., 41: 2-18. VanEgeren, L.F. (1979b) Cardiovascular changes during social competition in a mixed-motive game. J. Pets. Soc. Psychol., 37: 858-864. VanEgeren, L.F., Sniderman, L and Roggelin, M, (1982) Competitive two-person interactions of type A and B individuals. J. Behat'. IVied., 5: 55-56. VanEgeren, L.F., Abelson, J.L. and Sniderman, L.D. (1983a) Interpersonal and electrocardiographic responses of type A's and type B's in competitive socioeconomic games. J. Psychosom. Res., 27: 53-59. Van Egeren, L.F., Fabrega, H. and Thornton, D.W. (1983b) Electrocardiographic effects of social stress on coronaryprone (type A) individuals. Psychosom. Med., 45: 195-203.
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© 1992 Elsevier Science Publishers B.V. All rights reserved 0167-8760/92/$05.00 INTPSY 00402
Social interaction, cardiovascular activation and the Type A behavior pattern T h o m a s Palm a and A r n e t ) h m a n b Department of Rehabilitation Medicine, Karolinska Hospital (Sweden) and b Department of Clinical Psychology, Unicersity of Uppsala, Uppsala (Sweden) (Accepted 4 June 1992)
Ke3' words: Social interaction; Psychophysiological reactivity; Coronary prone behavior
The purpose of the study was to explore the relationship between social interaction and cardiovascular activity during a conflict-inducingcommunication task in Type A and B subjects. One of the subjects, the leader, was instructed to lead the other subject, the follower, through defined routes on a c;ty map merely by help of instructions. The subjects were facing each other on each side of a screen which allowed eye contact but shielded the maps from view. 40 male students (mean age 24 years) exhibiting Type A or Type B behavior according to the Videotaped Structured Interview participated in the study. The results demonstrated large cardiovascular increases during task performance, particularly for leaders, in systolic blood pressure and heart rate. There were no main effects of Type A vs. Type B, but dyads composed of two Type As showed larger increase in diastolic blood pressure during the conflict phase of the task compared to dyads composed of Type Bs.
INTRODUCTION Evolution has shaped humans to be highly responsive to social events and stimuli (Ohman and Dimberg, 1984). However, psychophysiological research typically deals with responses to nonsocial situations, presumably because they are easier to control and manipulate experimentally. 0 h m a n and Dimberg (1984) pointed out that this practice puts investigators at the risk of missing evolutionary shaped behavior tendencies that may be most likely to generate ubiquitous physiological responding. Research on 'stress' may be taken as a case in point. In the laboratory, stress is induced, for example, by exposure to aversive stimuli, such as the cold-pressor test, by task performance under
Correspondence to: A. Ohman, Department of Clinical Psychology. University of Uppsala, Box 1225, 751 42 Sweden.
threat of shock, or perceptual conflicts such as in the Stroop color naming task. In real life, however, socially induced stress is probably much more prevalent and intense than stress due to exposure to aversive stimuli. When failing in task performance, it is not the failure per se that is most stress-inducing, but its social consequences in terms of criticism or 'lost face' in front of others. To capture these aspects of stress, it is necessary to use social experimental situations. Blakar (1980, 1984) has developed a promising experimental situation promoting what appears spontaneous social interaction under reasonably controlled conditions. This situation incorporates a central dimension of potentially stressful social interaction, that of dominance. Thus, one of the persons in the interacting dyad, the leader, is required to take a dominant role in symbolically guiding his partner, the follower, through the center of a city by help of a map. Each participant is faced with allegedly identical maps, which
102 are shielded from view by the partner. However, at a critical point, the maps do not match. As a consequence the follower gets lost, which sets the stage for dominance conflicts. Blakar (1980, 1984) used this task to study communication in families having a disturbed member, such as a schizophrenic child. His results indicated that individuals differ markedly in ways of coping with the communicative conflict. Thus, an interactional perspective, taking account of both individual and situational factors (l~hman and Magnusson, 1987) is called for in analysing the effects of the task. A potentially crucial concept of individual differences in this context is that of Type A behavior, because social dominance is one of its most important components (e.g., Straub et al., 1990). Furthermore, Thoresen and 0hman (1987) argued that analyses of this behavior pattern must consider the interaction between social situational conditions and characteristics of the person. Thus, it appears especially important to relate physiological reactivity among Type As to different social contexts. The overwhelming majority of Type A research, however, has been concerned with solitary task performance, and little attention has been paid to dyadic or group interaction. An exception is provided through a study reported by Abbott et al. (1987). They explored the relationship between behavior pattern and cardiovascular events when Type A and Type B subjects cooperated in dyads, and reported larger cardiovascular responses in Type As cooperating with other Type As than with Ty?e Bs. Similarly, Glass et al. (1980) showed that an overtly hostile opponent resulted in larger cardiovascular responses in Type As than in Type B subjects during a video game. Finally, VanEgeren and colleagues (I979a, b) have reported data from studies of social interaction in Type As and Bs. Their findings indicated (VanEgeren, 1979a, b; VanEgeren et al., 1982; VanEgeren et al., 1983a, b) that Type A individuals tended to be more aggressive, competitive and dominating than Type Bs. In some experiments, but not all, Type A showed larger heart rate and digital vasoconstriction responses, as well as cardiac arrhythmias, and ST segment depression. Any particular cardiovascular re-
sponse did not differentiate Type As and Bs in all experiments, but when it did, Type As were always more reactive than Type Bs. These studies indicate that differences in reactivity between Type As and Type Bs emerge when subjects are confronted with social situations engendering competition for dominance. The purpose of the present study was, firstly, to examine physiological correlates of the roles as leader and follower in the Biakar Communication Conflict Task. Secondly, we explored the relationship between the Type A behavior pattern and cardiovascular events during social interaction in this task. Thus, we examined physiological reactivity (SBP, DBP, HR), and subjective arousal in Type A and Type B individuals serving as leaders/followers, and interacting with partners of the same or the opposite category.
METHOD
Subjects The selection of subjects followed a two-step procedure. The first step used the Type A SelfReport Inventory (TASRI) (Blumenthal et al., 1985). A total of 320 law and economy students (113 males) answered the TASRI. In the second step, male subjects were invited to participate in a videotaped structured interview (VSI) (Friedman and Powell, 1984; Ohman et al., 1992) to diagnose Type A behavior, in descending order for subjects with high TASRI scores, and in ascending order for subjects with low scores, until 40 subjects had been recruited. The VSI is scored on the basis of observed signs of Type A behavior in gestures, speech and content. The derived scale of Type A behavior show good internal consistency, and good agreement between judges (intraclass 0.764), and adequate stability over time (r -- 0.65 for a 2 year period) (see Ohman et al., 1992). Swedish judges also show high interrater agreement with a judge from the Meyer Friedman Institute in San Francisco. Half of the recruited subjects were law students and the other half economy students. The age range was 20 to 30 years (mean -- 24 years). For VSI, total scores larger than or equal to a
I03
cutoff of 80 defined the Type A group and scores less than or equal to 69 defined the Type B group. Half of the subjects within each of the student categories were classified as Type A (n -20, mean = 95.1, S.D.-- 11.9) and the other half as Type B (n = 20, mean = 60.0, S.D. = 9.7) according to the VSI. One of the subjects (Type B) was on blood pressure medication. Each subject received $5.00 for taking part in the interview and $10.00 for the experiment. After the interview all participants completed two questionnaires, the Jenkins Activity Survey and the Heart and Lifestyle Type A Measure. However, results from these questionnaires will not be reported in this paper.
Apparatus and recording methods Two disposable 14 mm diameter HP-ECG electrodes were positioned bilaterally and precordially on the chest for optimal R-wave signal; the ground electrode was placed on the left shoulder.
The ECG signals were transduced and filtered throw a HP 8811 A amplifier. A Hewlett-Packard 7754-A four-channel polygraph displayed signals on paper from both subjects simultaneousbj. Paper speed was set to 2.5 mm/s. Heart rate (HR) was continuously recorded during rest and the experimental routes. Systolic and diastolic blood pressure (SBP and DBP, respectively) were measured with two laboratory-built automated blood pressure systems, utilizing the auscultatory method. The systems have been validated against intraarterial recordings with high correlations for SBP (0.97) and for DBP (0.81) (Eiiasson et al., 1983). The cuffs were placed on the subject's upper left arm if they were right handed, if lefthanded, placement was reversed. A microphone detecting the Korotkoff sounds was placed over the brachial artery. Cuff pressure and Korotkc,ff sounds were displayed on the polygraph. The pressures associated with the appearances (Phase I) and attenuation (Phase IV) of Korotkoff sounds
Leaders Map Followers Map
\
\
Fig. 1. The communicative situation with the conflict inducing manipulation (extra street) marked. The leader and follower's version of the map are shown left and right, respectively.
104 were recorded as systolic and diastolic blood pressure respectively, approximately once per minute during rest and task.
Procedure Subjects were seated in the laboratory and were told to sit quiet and relax during the initial rest period. The participants (Leader and Follower), sat at opposite ends of a table (1.5 × 1.5 m). The placement of Leaders and Followers were always the same. To ensure that subjects in the interacting dyads did not know each other, each dyad had one member from the law, and one from the economy student population. The subjects were facing each other on each side of a screen (40 cm in height) which allowed natural eye-contact but shielded the maps which were placed on the table in front of the subjects. The subjects were instructed (see Blakar, 1980, 1984), that one of the subjects, the Leader, was to lead the other subject, the Follower, through defined routes on a city map (see Fig. 1) by help of instructions. Two routes were marked with arrows on the Leader's map, one short and straightforward (1st route, the simple situation), and another longer and more complicated (3rd route, the conflict situation). No route were marked on the Followers map. The Leaders task was to explain the two routes to the Follower. The Follower then, had to try to find his way through the town. He was allowed to ask questions, for example, ask the Leader to repeat the explanations. The experimental manipulation was simply that the two maps were p,~t identical (see Fig. 1). An extra street was added on the Followers map. Thus, no matter how adequately the Leader explained or the Follower carried out the instructions, the Follower was still bound to go wrong. However~ the discrepancy between the two maps affected only the complicated 3rd (experimental) route. A pilot study on seven men and women with the original version of the experimental situation (Blakar, 1980, 1984) prompted the following modification: to promote confidence in the procedure, an extra map-route, the 2nd route was added. It had the same extension as the 3rd route, but did not involve any discrepancy be-
tween maps. In adding the second route, the idea was to enhance the feeling of 'a shared social reality" which would potentiate the (subjective and physiological) effects when communication failed during the 3rd route. In the instruction, time pressure was added because of its conceptual relevance for Type A behavior. The 1st route was merely for practice in the task and included no time pressure or physiological recording. The 2nd route and 3rd route were time-limited. Time-limit was 5 min. Time pressure was emphasized by a visible digital clock which showed min, s and 1/10 s. The clock was started when the experimental routes begun. Furthermore, the experimenter (a male) announced the elapsed time loudly at half minute intervals. The subjects were told that physiological activity would be recorded simultaneously and continuously throughout the 2nd and 3rd route but that the 1st route was only for practicing and no measure of any kind was taken. Self ratings. To assess experienced arousal during rest and the two routes with social interaction, an adjective checklist was administered. It consisted of items from four factors: energy, stress, irritability and task involvement. The relevance of these factors for phenomenological arousal has been documented by Bohlin and Kjellberg (1973) and Kjellberg and Bohlin (1974). The rating sheets were administered after rest, and after the 2nd and the 3rd routes. The subjects were told to retrospectively rate their mood as felt under the preceding task, and not to reflect on their current feelings.
Design and statistical analyses Scoring of cardiovascular data. Only results from the 3rd route were of interest and are presented here. The task lasted for a maximum of 5 min. Pre-conflict, conflict and post-conflict period means were based on two measurements. The post-conflict, that is, the recovery value, was based on the last measurement or the value that followed immediately after con~qict solution. The pre-conflict period mean value was based on measurement at onset and after 30 s of Task performance. The conflict period mean value was based on one measurement beginning with the
105
first unequivocal indication that the follower was lost and another measurement one minute later. Baseline values were collected and averaged during the three last minutes of the initial rest period. Heart-rate was scored by counting the number of successive R-waves occurring during a 20 s period ( × 3 in the analysis), beginning with the measurement of blood pressure onset. The basic experimental design was a 2 Behavior-Pattern (Type A and Type B) × 2 Function (leader and follower) × 3 Taskperiod (pre-confilet, conflict and post-conflict). Behavior Pattern and Function were between-subject factors and Taskperiod was a within-subjects factor. To test the importance of group composition, a two-factor dyad between groups design (A_A, AB, BA and BB, the first letter in dyads denotes the leader), with repeated measures (pre-conflict, conflict and post-conflict)was used. The effects examined in this set of analyses included the main effect of Group and the interaction between Group and period. All effects were tested by analysis of covariance (SAS, 1985) using the appropriate baseline (rest values or rest ratings) as the covariate. The probability value (0.05) associated with the Greenhouse-Geisser correction procedure for repeated measures (GreenhouseGeisser, 1959) was used, because of possible violations of the sphericity assumption. Tukey's Honestly Significance Difference (HSD) test were conducted post-hoc, on adjusted means, to identify significant differences where appropriate. Self-rating. Each arousal factor (Energy, Stress, Interest and Irritability) was Separately analyzed according to the same basic experimental designs as for cardiovascular data but without repeated measures.
TABLE I Baseline means for Type A / B Leaders / Followers Standard deviations in parenthesis
Type A Type B
L F L F
SBP
DBP
HR
115.4 (12,8) 114.7 (8,2) 115.2 (12.5) 122.6 (7.0)
71.3 (6.8) 67.4 (9.1) 69.4 (7.4) 66.1 (9.8)
70,5 (7.4) 75,0 (10,1) 69.2 (9,9) 74,6(11.1)
Thus, during social interaction the Leaders were about 20 mmHg above the followers which generated a highly significant main effect for Function (F(1/35) = 27.03, P < 0.001) in the ANCOVA, and this difference was apparent throughout the three task periods. No significant effect due to Behavior-Pattern was revealed. A within-subjects main effect of task period ( F ( 2 / 7 0 ) - 4.05, P < 0.05) appeared, which primarily was attributable to a decrease in SBP after the conflict period. ~/B L/F
~ TYPE A TYPE B
148
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1;32 D. rn 128
124
F
l:'e
RESULTS
Cardiovascular effects SBP. No significant differences were obtained at baselines for Behavior-Pattern and Function (see Table I). However, the leaders showed a dramatic increase in SBP during task performance whereas the followers showed little change (see Fig. 2).
1£6
REST
BEFORE
DURZNG
AFTER
Fig. 2. Systolic blood pressure in a conflict inducing communicative task for type A and B persons holding a role as leader (L) and follower (F), respectively. Task period means, preconflict (Before), conflict (During) and post-conflict (After) are corrected for baseline (rest) levels.
106 RiB
TABLE 1I
Cardiovascular effects for interacting dyads during the communication conflict period Dyads AA AB BA BB
rnmHg I
ss ,',-
DBP
HR
131.0 (4.3) 131.0 (4.3) 129.0 (4.3) 127.0 (4.3)
88.3 (2.7) 80.8 (2.7) 78.8 (2.7) 79.0 (2.7)
78,8 (2.1) 81.0 (2.1) 82.5 (2.1) 79.9 (2.1)
__ T Y P E
A
~- T Y P E
B
..! t
Adjusted means (S.E. in parentheses) SBP
L/F
B8f
//
O't-t !
To examine differences between dyads across periods, a 4 x 3 ANCOVA was performed. It generated a significant Dyad × Taskperiod interaction (F(6/70) = 2.45, P < 0.05). The interaction suggested differential dyad responding over taskperiods. However, as shown in Table II, the groups were not different during the conflict part of the task. Thus, post-hoc analyses showed that the effect could be attributed to differential developments after the conflict when dyad BA significantly increased their SBP levels, compared to the other dyads, who recovered their responses. DBP. The analysis for DBP showed no differences in baseline (see Table I) and the ANCOVA gave no significant between-subjects effect for Behavior-Pattern or Function, but a main effect of Taskperiod (F(2/70) = 5.07, P < 0.05). The latter effect was due to an overall increase from pre-conflict to conflict, and then a decline in activity (see Fig. 3). The analysis of Dyads revealed no significant between-subjects effect but a significant Dyad × Taskperiod interaction (F(6/70) = 2.34, P < 0.05). Tukey tests revealed (see Table !I) that the
,:/
",\
,
,/
/ /
74
/
/ /
//
/
"-.,
/ f"
I //
REST
BEFORE
DURZNG
DBP in dyad AA was significantly higher than that of groups BB and BA during the conflict. Group AB was slightly above the latter two groups, but it was just significantly below the AA group. HR. Although the leaders tended to have somewhat lower baselines than followers (see Table I), the differences were not significant. The
Self-rating effects for Type A / B Leaders and Followers Adjusted means (S.E. in parentheses) mean rest
Energy Stress Interest Irritability
24.3 13.9 12.5 6.1
RFTER
Fig. 3. Diastolic blood pressure in a conflict inducing communicative task for type A and B persons holding a role as leader (L) and follower (F), respectively. Task period means, oreconflict (Before), conflict (during) and post-conflict (After), are corrected for baseline (rest) levels.
TABLE !11
Factors
,~
Type A
Type B
L
F
L
F
30.5 (0.97) 21.4 (!.7) 12.5 (0.47) 8.9 (0.97)
30.6 (0.97) 20.8 (i.7) 12.9 (0.48) 9.8 (0.99)
29.4 (0.96) 19.6 (I.7) 12.5 (0.48) 8.2 (0.93)
29.9 (0.96) 21.1 (1.7) 12.,3 (0.47) 8.4 (0.93)
107 R/B
L/F
~
HR
;
TYPE R
~" T Y P E B
92 L
L
Self-rating effects The results of self-rating effects in the arousal factors for Type A / B leaders and followers are summarized in Table III. Effects of Function or Behavior-Pattern were not significant in any of the factors.
DISCUSSION
,Be p--
p
f
,,] / .i
.+ .+]i // "
F
i/,,
r //// r ill
REST
6EFORE
DURZNG
RFTER
Fig. 4. Heart rate in a conflict inducing communicative task for type A and B persons holding a role as leader (L) and follower (F), respectively. Task period means, pre-conflict (Before), conflict (during) and post-conflict (After), are corrected for baseline (rest) levels.
HR ANCOVA generated a significant between main effect for Function, ( F ( 1 / 3 5 ) = 10.46, P < 0.01), and a Function × Behavior-Pattern interaction ( F ( 1 / 3 5 ) = 3.83, P = 0.05). The interaction could be attributed to a larger difference between leader and followers among Type Bs than among Type As (see Fig. 4). No significant main effect was due to Behavior-Pattern. A within subject interaction between Task period and Function ( F ( 2 / 7 0 ) = 3.7, P < 0.05) suggests different changes in activity over taskpe~'iods for leaders and followers. Post-hoc analyses revealed significant differences between leaders and followers before and during the conflict, but the decrease in activity was more pronounced among the leaders than for followers after the conflict. Two way analyses of dyads revealed no significant effects (see Table II).
The present results demonstrated large increases in cardiovascular activation during social interaction and interpersonal conflict in subjects assigned the role of guiding another subject through a task. These effects were particularly obvious for SBP, which produced change from baseline of about 22 mmHg, independently of behavior pattern. Thus, for this measure the role or the position in the social interaction proved a potent factor in determining cardiovascular reactivity. For DBP, however, there was no reliable effect associated with the position of leader. The overall increases in SBP, HR and partly in DBP deafly suggest enhanced sympathetic load on the cardiovascular system during social interaction. For subjective arousal there were no significant effects but a tendency for the factors Energy and Stress to change from baseline to task (see Table III). The fact that clearcut changes were observed in SBP and HA, but not in DBP, may be taken to suggest that the cardiovascular effects reflected an increased fl-adrenergic effect on the myocardium rather than an a-adrenergic effect on the peripheral vascular bed. To be leader in social interaction under time pressure, therefore, appears very effective in prompting cardiovascular activation. There were no significant main effects of behavior pattern, but when looking at dyadic interaction during the conflict, Type As were s;gnificantly more reactive in DBP (of about 8 mmHg) when they interacted with another Type A, than when two Type Bs interacted with each other. These data are similar to those reported by VanEgeren et al. (1979a) in that they suggest that stress-induced reactivity is particularly obvious when two Type As interact socially. A number of
108
studies (Diamond et al., 1984; Smith et al., 1984; Dembroski et al., 1977). reported sympathetically mediated effects in cardiovascular parameters such as SBP and HR to different forms of challenges, but minimal changes in DBP for Type As. From the conclusions reached by VanEgeren (1978) it is tempting to speculate about Type A, aggression, and interpersonal disagreement. VanEgeren found anger expression to be uniquely related to diastolic changes. The more the subjects expressed anger, the lower were their DBP levels. During this study all the dyads exhibited low overt interpersonal antagonism and there were few signs of overt anger during interactions, and in general the subjects reported low levels of irritability, see Table Ill (max 25). Yet from VanEgeren's (1978) findings, the DBP data in this study may be taken as indicating considerable covert anger and irritation, particularly when Type As interacted with each other. Further support for an interpretation of DBP as related to anger comes from the literature on the psychophysiology of emotion. Thus, Roberts and Weerts (1982) reported change in diastolic blood pressure to be significantly greater for high anger than for high fear during mental imagery. Furthermore, Ax (1953), found support for specificity in physiological response patterns in that an anger producing situation resulted in rises in DBP and declines in HR, a different pattern compared to the fear situation, which primarily resulted in elevated SBP and HR. For HR, there was a reliable interaction between Function and Pehavior Pattern to the effect that the roles as Leader and Follower were much more clearly separated among Type B than among Type A individuals (see Fig. 4). Thus, Type B leaders were above Type A leaders, and Type B followers were below Type A followers. Assuming that Type As are more dominant than Type Bs (e.g., Straub et al., 1990), one interpretation of this finding is that it is particularly stressful to enact an incompatible role, thus resulting in elevated HR levels. Whereas Type A leaders simply foUowed their inclination towards dominance, Type B leaders had to act in opposition to their tendencies toward submissiveness when fulfilling their role in the social interaction. Simi-
lady, Type A followers may have been provoked by being placed in a situation where they had to yield to a person they perceived as less dominant than themselves. This interpretation is in line with the findings by Straub et al. (1990) who found evidence for more dominance in Type A males and females than for their respective Type B counterparts in a competition paradigm. The effect of speech on blood pressure provides a potential confounding factor in the attribution of our results to social interaction factors such as dominance. Lynch (1985) demonstrated a dynamic relationship between speech and BP reactivity. As the subject talked, there was a concomitant rise in blood pressure, and the increase was related to formal characteristics of the speech. Similar data were reported by Smith and Allred (1989), who examined cardiovascular reactivity during speaking and listening to a partner, in a debate format. They found that their subjects had higher SBP (4 mmHg), DBP (7 mmHg) and RR (7 bpm) when they spoke than when they listened. In the present study it is likely that the leaders talked more than the followers, because of their dominant role in the interaction. This difference in speech activity, in turn, may have prompted heightened SBP and also HR. However, the effects of speech on bioodpressure, reported by Lynch (1985) and Smith and Allred (1989), are unlikely to provide a complete account of our findings. In general, the effects of speaking reported by Smith and Allred (1989) were small compared to the effect of social position in our study (e.g., for SBP, 4 mmHg vs. 22 mmHg). Furthermore, they examined differences between listening and speaking conditions. In our study, however, both leaders and followers spoke, and sometimes the follower was verbally more active than the leader. Feldstein and Welkowitz (1978) suggested that participants in dyadic interactions tended to match each others voice style, for example, with regard to intensity. According to Siegman et al. (1990)cardiovascular reactions tend also to match in partners engaged in social interactions. Thus, the cardiovascular effects may not exclusively be explained by speech-related reactivity, but may also reflect different social comparison processes. In accordance with this
I09
conclusion, Henderson et al. (1990) found that HR could not be accounted for in terms of speech associated cardiovascular changes, but appeared to be most sensitive to situational demands. Finally, Linden (1987) found that the emotional significance of the speech content was more important for autonomous activation than was the speech act per se. Thus, in conclusion it appears that social, situational and emotional factors have effects on blood pressure above what could be expected from the simple act of speaking per se. From the shapes of the curves in Figs. 2, 3 and 4, it appears that the cardiovascular activity increased abruptly with the start of the task, and that there was minimal further increase during the conflict phase of the task. The reason for this might be that the conflict-inducing situation was too simple and easy to solve. Some of the dyads solved the conflict situation, i.e., they identified the critical point, settled the disagreement, and chose a new strategy. This is in marked contrast to the reports of Blaker (1980, 1984), which suggested that most of his subjee*~ ~ot stuck in the conflict. However, the present subject population was students, who may be expected to use their high verbal and communicative skills to help solving the conflict. The participants quickly attributed the verbal disagreement to the maps, realizing that they were not identical. Often they also identified the critical point. Thus, they handled the potential conflict in an efficient, functional, and non-emotional manner. Another reason for not overtly showing anger might have been that the subjects were unknown to each other, which might have inhibited overt signs of anger. It is likely that the odds of eliciting hostility would be better if the subjects in a dyad know each other well, for example if they were spouses. Given the intrinsic interest of the task for the subjects, it is likely that it would be quite arousing even without the use of different maps for leaders and followers. It may be more effective to manipulate intrinsic aspects of the task, such as its complexity, or perhaps, the time available to complete the task. By omitting map discrepancy, the task could be replicated several times, enhancing its reliability, and allowing, e.g., measurement of change after interventions. Thus, there
are several ways that the present experimental situation can be improved as a method to elicit cardiovascular reactivity in an ecologically meaningful way.
ACKNOWLEDGEMENTS This investigation was supported by grants from the Bank of Sweden Tercentenary Foundation and from the Swedish Council for the Humanities and Social Sciences to the second author. The authors would like to thank Gunilla Bohlin for helpful advice in preparing the study and Kristina Stjernl6f for conducting all Type A interviews.
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