AGGRESSIVE BEHAVIOR Volume 14, pages 245-254

Aggression, Self-Confidence, and Cardiovascular React ions in Corn pet it ive Performance in Adolescent Boys Liisa Keltikangas-Jarvinen and Mirja Keinonen

Department of Psychology, University of Helsinki, Helsinki, Finland

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Interactions between suggested risk factors for the development of coronary heart disease (namely aggression, competitive performance, and cardiovascular reactions) were studied in 36 adolescent boys. Different manifestations of aggression were mea- sured using a structured interview, the aggression-impatience factor of the MYTH test, and observation. Self-confidence was assessed by means of an interview. The perfor- mance tests used were the Stroop Color Word test and the P-factor test. Cardiovascular reactions were measured using an automatic noninvasive sphygmomanometer with a continuous recording system. Results showed that the significance of aggression in performance or competition cannot be evaluated separately; aggression in itself had an injurious effect on performance, but when combined with high self-confidence it resulted in a high level of performance. High cardiovascular reactivity was related to competitiveness rather than aggression. The results emphasize that before intervention programs for behavioral risk factors of coronary heart disease are planned, there are many questions to answer.

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Key words: competition, coronary heart disease

INTRODUCTION

So-called type A behavior has been implicated in the pathogenesis of coronary heart disease (CHD) [e.g., Friedman and Rosenman, 1974; Jenkins et al., 1974; Rosenman et al., 19751. Type A behavior is an action-emotion complex characterized by extremes in achievement striving, an exaggerated sense of time urgency, impatience, and an aggressive behavioral style [Rosenman, 19781. Type A persons are competi- tive, compulsive, hard-driving, restless, and ambitious [Chesney et al., 1981; Van

Received for publication October 16, 1987; revision accepted February 1, 1988.

Address reprint requests to Liisa Keltikangas-Jarvinen, Department of Psychology, University of Hel- sinki, Fabianinkatu 28, 00100 Helsinki 10, Finland.

0 1988 Alan R. Liss, Inc.

246 Keltikungas-Jarvinen and Keinonen

Egeren et al., 19831 and wish to maintain control over environmental demands and requirements [Matthews et al., 19771.

The means by which type A pattern increases the risk of CHD is uncertain. One possibility is an exaggerated cardiovascular responsivity of type A individuals. Type A individuals respond to environmental challenges (especially to situations that in- volve threat to the person’s sense of competence) with greater sympathetic nervous system and adrenomedullary activity [e.g., Goldband, 1980; Herd, 1978; Williams, 19781. It has been repeatedly found that type A individuals show elevated blood pressure and increased heart rate in performance and competition [e.g., Manuck et al. , 1978; Lovallo and Pishkin, 19801. When this physiological responsivity becomes a chronic response to ordinary life demands, it may, in time, result in increased coronary atherosclerosis and subsequent CHD [Newlin and Levenson, 19821.

Aggression has been suggested to be a potential factor linking type A behavior with cardiovascular responses through autonomic arousal and overactivity of the sympa- thetic nervous system. The tendency toward aggression is seen as a defining trait of the type A behavior [Van Egeren et al., 19831, and elevated blood pressure and increased pulse frequency are known to be physiological correlates of behavioral aggression [Lagerspetz, 19701. Although the potential role of aggression as a link between the behavioral and physiological risk factors of CHD has been strongly emphasized, many questions of primary importance have been ignored. Research has focused on the physiological responsivity of type A individuals in task performance and competition, while the transmitting role of aggression has been supposed rather than empirically supported. There is evidence that aggression elicits autonomic arousal, but there is no evidence that individuals who have been assessed by question- naires as being aggressive and competitive show great cardiovascular reactivity in performance. Further, aggression per se has remained a vague concept in studies on risk factors of CHD. Sometimes it has been applied to a personality trait, sometimes to a situation-specific anger, and sometimes as the likelihood of using aggression as a coping mechanism when frustrated.

An individual’s own standards of achievement, his sense of competence, as well as the level of his performance may be of importance when the correlations between aggression, task performance, and cardiovascular reactivity are studied. Previous research has , however, concentrated on physiological responsiveness of type A individuals in performance, while the above-mentioned aspects have been largely ignored. It can also be hypothesized that the significance of aggression cannot be separately evaluated as it may depend on a combination of personality factors in which it is manifested.

Research on physiological responsivity of type A individuals has focused on adults, and there are only a few studies with children [e.g., Lundberg, 1983; Matthews and Jennings, 19841. Atherosclerosis, a pathogenic process underlying CHD begins, however, during childhood and adolescence [Strong and McGill, 19691, and interven- tion must investigate the significance of risk factors close to the onset of the patho- genic process.

The present study investigated relationships between different manifestations of aggression, self-confidence, performance, and cardiovascular reactions in adolescent boys. The following questions were posed: 1) do different manifestations of aggres- sion play different roles in task performance and competition, 2) is the significance of aggression dependent on a level of self-confidence, 3) is aggression related to an

Aggression and Selj-Conjidence in Competition 247

increase in pulse frequency and blood pressure in performance, and 4) how is aggression related to the task performance level?

SUBJECTS

Subjects were a randomly selected sample of 36 15-year-old healthy boys living in Helsinki. They comprised one cohort of the “Finnish Multicenter Study on Athero- sclerosis Precursors,” which is a prospective study on the development of somatic and behavioral risk factors of CHD [Akerblom et al., 19851. MATERIALS AND METHODS

The following manifestations of aggression were evaluated.

Aggression as a Component of Type A Behavior

This was measured using the aggression-impatience factor of the Matthew’s Youth Test for Health, which assesses type A behavior in children [Matthews and Angulo, 19801. This test evaluates aggression with questions such as “I like to argue or debate” and “I easily get into fights.” This variable will be called in this paper “aggression as a trait. ”

Likelihood of Reacting Aggressively When Frustrated

Subjects had five frustrating situations in the ordinary life of adolescent boys described to them. For example, you have been elected into a football team. Near the time when the first match is going to be played you catch a cold and miss the game. After each story the boys were asked how likely it was that they would behave aggressively in such a situation. The response alternatives were very likely, 2 points; not very likely, 1 point; and not at all likely, 0 points. This manifestation will be called “aggression as a coping.”

Situation-Specific Aggression Subjects were asked after each performance test (a total of four) whether they felt

interest, anger, relaxation, or tiredness during the test. The scoring for each feeling was on a 3-point scale (greatly, 2 points; a little, 1 point; not at all, 0 points). The points for anger were scored separately and refer in this paper to situation-specific aggression.

Aggressive Expressions

Aggressive expressions were observed during each test on the basis of movements and verbal expressions and scored in the following way: clear evidence, 2 points; slight evidence, 1 point; no evidence, 0 points.

In addition the assessment of self-confidence or self-esteem of the subject was included. This was measured in the following way: subjects were asked three ques- tions with yes-no response alternatives, derived from Coopersmith’s Self-Esteem Questionnaire [Coopersmith, 19691. They were: “I am as popular as others,” “My parents like me,” and “The teacher likes me.”

Subsequently, the subjects were interviewed about their school performance and future plans using a structured interview. After every statement relating to a need for achievement expressed by the subject (e.g., “I want to do better at school,” “I am going to go to university,” or “I want to be a good doctor”) the subject was asked,

248 Keltikangas-Jarvine4 and Keinonen

how do you think this happens? One point was given for each answer that was based on the subject’s trust in his own efforts, e.g., “I can do it if I try.” The total sum of those points added with the score derived from Coopersmith’s test made up the variable called self-confidence.

CARDIOVASCULAR REACTIONS

Systolic and diastolic blood pressure and pulse frequency were measured during each test using an automatic noninvasive sphygmomanometer with a continuous recording system. Pulse frequency was found to be the most appropriate parameter; the duration of different tests was rather short, and changes in pulse frequency were more rapid than those in blood pressure. In each test, the highest increase of pulse frequency was found between the value preceding the test (the rest value) and the first reactivity value, i.e., when the subject started the test. Among the physiological variables this parameter had the highest correlations with performance and personality variables. Covariance analysis showed that a rest value and a first reactivity value of pulse frequency were independent of each other. Therefore, this parameter was included into the further analysis.

PROCEDURE TO MEASURE PERFORMANCE AND COMPETITION

Performance was measured using the Stroop Color Word Test and the P-factor test. Task performance, maximum performance, and performance in competition were evaluated.

In the Stroop Color Word Test the subject must name the colors of the inks in which words are printed and ignore the words themselves. For instance the correct response to the word “yellow” is “blue” if it is printed in blue ink. The test elicits emotional reactions because the subject has to respond against his cognitive set of the moment. Consequently, the Stroop Test has been considered appropriate for measuring perfor- mance capacity in frustrating situations.

In the present study, the subject was first instructed to complete the test quickly and correctly (task performance) and then he was told that he was rather good but could probably improve his performance if he tried his best. He was then asked to complete the test again as quickly and correctly as possible (maximum performance). In the second test a different list of colors was used, but the effect of learning could not be avoided. If the subject finds a method of solving the double bind by focusing on the color and not the words themselves, the difficulties are greatly reduced, and the potential frustration decreases. In both tests the dependent variables were the time used and number of errors.

The P-factor test consisted of 50 pairs of numbers and letters, of which the subject had to mark those pairs that were unlike. At first the subject was instructed to complete the test quickly and correctly (task performance). Then he was told to complete the test again (a new list was used), competing with the experimenter. Time and the number of errors were measured. In order to elicit more aggression in the competition, it was arranged that the experimenter always won. Afterwards, each subject was told about the deception, and he was informed that his performance was very good (at this, strong aggression was aroused in two boys, though in the majority of cases the subjects felt more relaxed when they discovered the real situation). The time taken and the number of errors were measured.

Aggression and Self-confidence in Competition 249

In order to create a real sense of competition, the boys were told that a total of 36 boys participated in the test and that the best would be given a prize. Afterwards, they were all given a prize and were informed that the idea of the test was to try one’s best, the number of mistakes and the performance time being irrelevant.

RESULTS Task Performance

The results for the Stroop Test showed that when the subjects were asked to do their best (maximum performance) the performance as a whole slightly improved, i.e., time, mistakes, and their standard deviation decreased. There was a significant positive correlation between time and mistakes in maximum performance but not in basic performance (Table I).

In the P-factor test, competition had the effect of decreasing performance time but increasing the number of mistakes, although it did not influence the ranking of the subjects on those variables. Both in performance and in competition, there was a negative correlation between time and mistakes (Table 11).

Correlations Between Aggression, Self-confidence, Pulse Frequency and Performance

Correlation analysis (Spearman’s r) showed that aggression as a coping mechanism, anger, and self-confidence were associated with performance, but aggression as a trait (the aggression-impatience factor of type A behavior) and behavioral aggressive expressions were not. Aggression as coping (later referred here to as aggression) impaired the performance; it increased both the time and the mistakes. The relation-

TABLE I. Means and Standard Deviations for the Stroop Test

Means Correlations M SD 1 2 3

1. Time/performance 59.0 14.1 2. Mistakes/performance 1 .o 2.2* 2. .08 3. Time/maximum performance 51.7 14.0 3. .&I** .19 4. Mistakedmaximum performance 0.6 0.9* 4. .25 .26 .35*

* P < .01. **P < .001.

TABLE 11. Means and Standard Deviations for P-Factor Test

Means Correlations M SD 1 2 3

1. Timelperformance 158.7** 45.4 2. Mistakes/performance 3.4 3.8 2. - .30 3. Timelcompetition 143.4** 44.3 3. .go** - .26 4. Mistakes/competition 4.0 3.1 4. - .31* .63** -.41*

*P < .01. **P < ,001.

250 Keltikangas-Jarvinen and Keinonen

ship was stronger in the Stroop Test, which is not surprising given the frustrating nature of that test (Table 111).

Situation-specific anger correlated with a short performance time but a large number of mistakes (Table 111).

The effect of high self-confidence on performance was positive; it decreased both performance time and the number of mistakes, the negative correlation between self- confidence and time being higher than that between self-confidence and mistakes. The effect of self-confidence was most obvious in the frustration-eliciting perfor- mance (the Stroop Test). When the subjects were informed that their performance was only satisfactory and a better result was expected, the significance of self- confidence decreased (Table 111).

The correlation between aggression and self-confidence was - .56. Aggression did not correlate with the changes in time and number of mistakes when

maximum performance or competition was required. High self-confidence was related to a slight change between different performance situations. Individuals with high self-confidence had such a good basic level of performance that they could not radically improve it. Individuals who felt angry in the test could not decrease their performance time but their mistakes increased in competition (Table IV).

The increase in pulse frequency between the resting value and the first reactivity value did not correlate statistically significantly with aggression or self-confidence. There was, however, a tendency for high aggression to be related to a small change in pulse frequency, whereas self-confidence was related to a marked change in pulse frequency. The rest value of pulse frequency did not differentiate the high and low aggression groups or the high and low self-confidence groups. This study suggested that aggression was not related to high cardiovascular responsivity .

In the P-factor test, a large increase in pulse frequency was related to a short performance time and a small number of mistakes. In the Stroop test, a short performance time but a large number of mistakes correlated with a large increase in pulse frequency (Table 111).

interaction Between Aggression, Self-confidence, Pulse Frequency, and Performance

Interaction between aggression, self-confidence, pulse frequency, and performance was studied using two-way variance analysis and regression analysis. Regression analyses were calculated 1) using aggression and self-confidence separately as inde- pendent variables and 2) using their interaction as an independent variable, while different performance variables were treated as dependent variables.

Aggression, self-confidence, and performance. The results showed that in each performance situation, independent of the type of performance test, aggression as coping and self-confidence constituted a significant combination, while anger, aggres- sion as a trait, and observed aggression were not of importance here. The combination was always the same: high aggression combined with high self-confidence resulted in a short performance time and in a small number of mistakes independent of the type of performance test adopted, while high aggression combined with low self-confi- dence resulted in long performance time and a great number of mistakes. Because two-way variance analysis and regression analyses all resulted in the same findings only the results of regression analyses are reported here (Table V).

Aggression and Self-Conjidence in Competition 251

TABLE In. Correlations of Self-confidence, Aggression, Anger, and Pulse Frequency With Performance?

Stroop test P-factor test

Performance performance Performance Competition Time Mistakes Time Mistakes Time Mistakes Time Mistakes

Maximum

1. -.31* -.35* -.16 -.16 -.41** -.02 - .32* -.lo 2. .a** .38* .43** .32* .23 .09 .22 .01 3. -.21 .31* -.41** .28 - .20 .20 - .07 .31* 4. -.50** .16 -SO** .21 - .20 - .20 -.15 - .40

t l = Self-confidence; 2 = aggression; 3 = anger; 4 = increase in pulse frequency in performance (rest value of pulse frequency subtracted from the pulse frequency at the beginning of the task). *P < .05. **P < .01.

TABLE IV. Correlations of Self-confidence, Aggression, and Anger With Changes of Performance?

Stroop test P-factor test 1 2 3 4

Self-confidence -.32** - .29* - .22 .10 Aggression .10 .25 .04 .ll Anger . l I -.16 -.45** .31*

tl = Difference when a maximum performance time has been subtracted from a performance time; 2 = difference when the mistakes in maximum performance are subtracted from the mistakes in performance; 3 = difference when a competition time has been subtracted from performance time; 4 = difference when mistakes in performance have been subtracted from mistakes in competition. *P < .05. **P < .01.

TABLE V. Regression Analysis Showing a Dependence Between Performance and 1) Aggression and Self-confidence; and 2) Their Interaction t

Self-confidence Aggression Interaction of them R SD t R SD t R SD t

1. 2.80 1.95 ,161 9.66 3.37 ,008 -1.78 0.81 .036 2. 0.33 0.30 ,277 1.40 0.52 ,012 -0.28 0.12 ,030 3. 4.68 1.87 ,018 11.39 3.23 ,001 -2.08 0.77 0.12 4. 0.27 0.12 ,035 0.69 0.21 ,003 -0.13 0.05 ,013 5. -2.30 6.63 .732 12.27 11.48 .292 -3.19 2.74 ,254 6. 0.04 0.61 ,837 0.08 0.06 ,609 0.04 0.25 ,877

8. -0.68 0.48 ,311 -1.10 0.84 ,210 0.25 0.20 ,219

'(R = Regression coefficients; SD = their standard errors; t = values of t-test. 1. Stroops: performance time; 2. Stroops: performance mistakes; 3. Stroops: maximum performance time; 4. Stroops: maximum performance mistakes; 5. P-factor test: performance time; 6. P-factor test: performance mistakes; 7. P-factor test: competition time; 8. P-factor test: competition mistakes.

7. -2.98 6.81 ,187 7.03 11.78 ,555 -1.46 2.82 ,609

252 Keltikangas-Jiirvinen and Keinonen

They show that when aggression and self-confidence were treated as independent, aggression played a role in all Stroop variables, and self-confidence only played a role in maximum performance (Table V). This slightly conflicts with the results of correlation analysis. It does not change the interpretation, but it does have an effect on the level of significance. Further, the interaction of aggression and self-confidence was statistically significant for all Stroop variables (Table V). The significance level was highest in maximum performance in the Stroop test.

The following regression equations show the contribution of dependent and inde- pendent variables:

Regression equation for maximum performance time in the Stroop test was y l = 4.68 * xl + 11.34 * x2 - 2.08 * x "2 -+ 26.18 (yl = competition time in the Stroop test; x l = self-confidence; x2 = aggression) and shows that when self-confidence and aggression are high, a maximum performance time is short; conversely, when self-confidence is low but aggression high, performance time is long.

Regression equation for mistakes in maximum performance in the Stroop test was y2 = 0.27 * xl + 0.68 * x2 - 0.13 * xl * x2 - 1.15 (y2 = number of mistakes in the competitive Stroop test; xl = self-confidence; x2 = aggression) and shows that when self-confidence and aggression are high a number of mistakes is small; con- versely, when self-confidence is low and aggression high, a number of mistakes is large.

Aggression, self-confidence, pulse frequency, and performance. The analysis of variance showed a statistically significant interaction between aggression, increase in pulse frequency, and performance in the Stroop test, both in task performance and in maximum performance. The results in maximum performance are seen in Table VI. They show that, independent of the level of aggression, a high increase of pulse frequency is related to a short performance time, and they also show that high aggression combined with a small increase in pulse frequency correlates with a markedly long performance time.

Self-confidence does not interact statistically significantly with pulse frequency and performance, but the results of variance analysis indicate that a low self-confidence combined with a small increase in pulse frequency is related to a long performance time and to a large number of mistakes, while a high self-confidence combined with

TABLE VI. Results of Variance Analysis Showing the Interaction of Aggression, Increase of Pulse Frequency, and Performance Time in the Competitive Stroop*

Mean of No. of Increase in performance subjects in

Aggression pulse frequency time the category

LOW Small 55.0 6 LOW Great 52.1 10 High Small 71.5 11 High Great 53.4 8

*High and low aggression scores as well as large and small increases in pulse frequency are based on the medians of the variables. The interaction was significant at the level P < .05.

Aggression and Self-Conjidence in Competition 253

small increase in pulse frequency results in a short performance time. In this study, self-confidence seems more noticeably related to the level of performance than cardiovascular reactivity; a combination of low self-confidence and slight cardiovas- cular reactions may be an indication of noncompetitiveness.

When the increase in pulse frequency was added to the interaction of aggression, self-confidence, and performance in the competitive Stroop test, the regression equa- tion y3 = 5.65 * xl + 11.96 * x2 - 2.34 * xl * x2 + 0.049 * x3 -0.535 * x4 + 28. 69 (y3 = performance time in the competitive Stroop; xl = self-confidence; x2 = aggression; x3 = resting value of pulse frequency; x4 = increase in pulse frequency; rest value subtracted from the first reactivity value in the competitive Stroop showed that the interaction of aggression and self-confidence retained its significance, but the addition of rest and reactivity values of pulse frequency as well as the total regression were not statistically significant.

DISCUSSION

Hostility and aggression have been amongst the most studied psychic risk factors for the development of CHD [e.g., Shekelle et al., 1983; Williams et al., 19801. The present results show that the evaluation of the significance of aggression is more complicated than has been admitted. From the different manifestations of aggression in this study, only aggression as a coping mechanism was related to task performance and competitiveness. This is not surprising as aggression as a coping mechanism is one way of dealing with the requirements and challenges of the environment. The results show that the significance of aggression is dependent on the personality combination in which it is manifested. Aggression in itself correlated to a poor performance independent of the type of task, but aggression combined with good self- confidence was related to a high level of performance.

The interdependence of aggression and self-confidence emphasizes the fact that personality is an entirety that cannot be divided into separate dimensions without risk of misinterpretation. The results do stress that there is a need to identify morbid aggression and to differentiate it from “life preserving” aggression. Usually this has been seen as a matter of degree, for when aggression exceeds a certain limit, it is injurious. The results suggest that it is a qualitative rather than a quantitative matter of personality. Low aggression associated with personality problems such as low self- confidence may lead to more risks than a high aggression that is under control.

Contrary to previous studies, individuals who scored high on aggression did not show high cardiovascular reactions in task performance or competition. Instead, high physiological responsivity was related to a rapid performance and competitiveness. In the light of this study it may be suggested that the combination of high aggression- low self-confidence-low pulse frequency was “injurious” because it resulted in a very low level of performance.

The present results raise more questions than they answer. However, they show that a suggested link, type A behavior-aggression-competitive performance-and phys- iological reactions still involves, at least in adolescents, many unresolved questions that need to be answered before intervention programs to modify type A behavior are planned.

254 Keltikangas-Jarvinen and Keinonen

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