This article was downloaded by: [New York University] On: 05 June 2015, At: 01:28 Publisher: Routledge Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK
Journal of Human Stress Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/vzhs20
Task Demand as Reflected in Catecholamine Excretion and Heart Rate a
Dr. Marianne Frankenhaeuser Ph.D. & Dr. Gunn Johansson Ph.D. a
Department of Psychology , University of Stockholm. Experimental Psychology Research Unit of the Swedish Medical Research Council , USA Published online: 09 Jul 2010.
To cite this article: Dr. Marianne Frankenhaeuser Ph.D. & Dr. Gunn Johansson Ph.D. (1976) Task Demand as Reflected in Catecholamine Excretion and Heart Rate, Journal of Human Stress, 2:1, 15-23, DOI: 10.1080/0097840X.1976.9937485 To link to this article: http://dx.doi.org/10.1080/0097840X.1976.9937485
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://www.tandfonline.com/page/termsand-conditions
TASK DEMAND AS REFLECTED IN CATECHOLAMINE EXCRETION AND HEART RATE
Downloaded by [New York University] at 01:28 05 June 2015
MARIANNE FRANKENHAEUSER, Ph.D., and GUNN JOHANSSON, Ph.D.
Immediate qffects and aftereffects of exposure to a color-word conflict task were studied in two groups 6f subjects, one of which petjiormed the task without auditory interference (“single conjlict*’), the other with auditory inteflerence (“double conflict”). Physiological arousal indices were more susceptible than performance measures to the level of task demand. Thus. the higher demand imposed by the double-conflict tusk was reflected in relatively larger increases of adrenaline excretion and heart mte, both during the conflict task and during the subsequent arithmetic task, whereas the performance measures remained unaffected. INTRODUCTION Many of the demands to which individuals living in technologically advanced societies are subjected relate to various forms of stimulus overload.’ One typical feature of today’s psychosocial environment is quantitative overload: another is qualitative overload.2 The former refers to the intensity and frequency of the stimuli impinging on the individual, while the latter refers to their complexity, novelty, incongruity, and a m b i g ~ i t y . ~ The concept of overload is based on the general notion of the organism’s limited capacity to handle incoming signals. On the physiological level, overload commonly is reflected in cortical, autonomic, or endocrine indices of arousal. On the cognitive level, increased effort ~
Both authors are affiliated with the Department of Psychology, University of Stockholm. Dr. Frankenhaeuser is Professor and Head of the Experimental Psychology Research Unit of the Swedish Medical Research Council; Dr. Johansson’s research is sponsored by the Swedish Work Environment Fund, and she is the research administrator of the Bank of Sweden Tercentenary Foundation’s Committee on Man and Working Life.
March. 1976
is the typical response to ~ v e r l o a dthis ; ~ often is accompanied by feelings of distress, irritation, and rush. On the whole, behavioral measures (e.g., task performances) appear to be relatively less sensitive, tending to remain unaffected under stimulus conditions which upset the subject’s physiological and subjective balance. The resistance of performance to overload has been interpreted in terms of compensatory adaptive reactions which are called into play during short-term stress and which tend to obscure harmful stress reactions by helping the individual to “pull himself together.”s Lately, attention has been drawn to possible negative aftereffects arising from intense efforts to cope with acute demands.6 Such a “cost of adaptation” may manifest itself ajier the termination of the stressor, in performance decrements, annoyance reactions or in heightened physiological arousal. When long-lasting and intense, aftereffects are likely to add to the wear and tear of the organism. Therefore, an important problem in stress research is to examine the duration of the various changes induced by demands of different kinds and intensities. In the present investigation, subjects were studied during and after exposure to a colorword conflict task (based on the Stroop test) representing two levels of demand on their capacity for sustained performance under distracting conditions. Catecholamine excretion, heart rate, and subjective reactions were used as indices of the effort required to perform the task under the two conditions. It was assumed that the more intense effort induced by the more demanding version of the conflict task would be reflected, not only in more pronounced psychophysiological changes during exposure to the stressor, but also in a slower return to physioJournal of Human Stress
15
TASK DEMAND AND AROUSAL logical and subjective baselines as well as in impaired performance on a subsequent arithmetic task.
The subjects of the two groups were matched for baseline levels of adrenaline excretion, determined by calculating the means for three values obtained in the control session (2.7+ 0.6 ng/min for Group I, and 2.6 +- 0.6 ng/min for Group 11). The control session also served as a check on the diurnal variation in catecholamine excretion. Group I11 attended one session only, in which mental arithmetic was performed. In this case, the arithmetic task was not preceded by the conflict task, and the arithmetic scores were used to assess possible aftereffects on performance. Experimental and control sessions took place between 8:30 a.m. and 1 p.m., each session consisting of three 70-min periods separated by 15-min intervals. The subjects had been asked not to eat before arriving in the laboratory, and they were served a light breakfast before the session started. A short interview was held in which each subject was asked about his general state of health, etc. He was then asked t o void before starting the session. In each interval the subject drank a glass of water to secure prompt micturition, and ate a piece of bread and butter in order to prevent hunger reactions from affecting
METHODS
Downloaded by [New York University] at 01:28 05 June 2015
Subjects, Design, and Procedure
Three groups of 16 subjects each participated in the investigation. Their ages ranged from 19 to 36 years (mean 24.3), their body weights from 51 to 90 kg (mean 71.21, and their heights from 160 to 195 cm (mean 181.6). The subjects of Groups I and 11 first had an introductory session (to be informed about the procedure and to get acquainted with the experimental setting), then a control session and an experimental session of about 4.5 hours each (Fig. 1). The control session was spent in the same way by all subjects - i.e., relaxing, reading, and listening to the radio. In the experimental session, Group I was exposed to a color-word task denoted "single conflict" and Group I1 to the same task with interfering auditory stimuli, denoted "double conflict." In both groups the conflict task was followed by a period of mental arithmetic and an inactivity period.
B r e a k f a s t + interview S i n g l e - c o n f l i c t task D o u b l e con f l i c t t a s k Arithmetic task inactivity
-
I
0
"
~
40
~
80
"
120
"
'
160
~
200
"
'
2LO
Time i n minutes
Fig. 1. Design of experiment.
16 Journal of Human Stress
March. 1976
FRANKENHAEUSER and JOHANSSON the variables to be examined. The control session was spent by the subjects in pairs; the experimental session was carried out individually except for the first period, to which the subjects came in groups of two-six.
Downloaded by [New York University] at 01:28 05 June 2015
”Single” and ”Double” Conflict Tasks
The conflict task was modelled on Card CW of Stroop’s’ color-word test. In essence, the test material consists of color words (red, blue, yellow, green) which are printed in different colors, the combination of words and colors being incongruent; for example, the word yellow may be colored red, etc. The subject’s task is to ignore the word and name the color of the print. The Stroop test has been modified in our laboratorys for use in a group situation. Two forms have been designed which represent different levels of task demand, the single-conflict task and the double-conflict task. In the former, color words are projected on a screen, one at a time, from a 16 mm film, and the subject has to respond to each word by marking the correct word on a response sheet with consecutively numbered rows; corresponding numbers are presented on a sound track synchronously with the visual stimuli in order to help the subject orient himself to the right row on the sheet. In the latter task, auditory stimuli are added by pairing the visually presented color word with an incompatible color word presented simultaneously on the sound track. Each task comprised 30 blocks of 21 stimuli each. The task proper was preceded by instructions and practice. The duration of the stimuli varied randomly from .4 - 1.0 sec. They were presented in random order at random intervals of .8 - 1.7 sec. The score was the-number of correct responses.
Catecholamine Excretion
In the introductory session the subjects had been informed about the factors that might affect catecholamine-excretion rates and which had to be avoided prior to experiments, e.g., intake of alcohol, drugs, and caffeine-containing beverages, smoking, strenuous exercise, etc. Urine samples were collected after each of the three successive periods in the experimental session. The urine volume was measured and pH adjusted to about 3 with 2 N HC1. The samples were stored at -18’ C until analyzed by the fluorimetric technique of Euler and Lishajko. Heart Rate
During the experimental session heart rate was monitored continuously by an electronic pulse-meter (San-Ei PM 101). Five readings were made at 10-min intervals within each period. For technical reasons heart rate was not measured in the control session. Instead, baseline levels were obtained by instructing the subjects to measure their pulse rate themselves by palpation of the radial artery upon rising in the morning; the score for each subject was the mean of two measurements taken on each of two consecutive days. Subjective Variables
After each period in the experimental session the subjects made self-estimates of different aspects of wakefulness and mood (e.g., “alertness,” “distress,” “irritation”). Ratings were made on graphic scales (120 mm), the endpoints representing the highest and lowest intensity that the subject ever had experienced in terms of each variable. The score was the distance (in mm) from the low-intensity endpoint. RESULTS
Mental Arithmetic
Performance
The mental-arithmetic test (Norinder, unpubl.) consisted of a series of 1-digit items arranged in pairs. The task was to add and subtract numbers according to certain rules. All operations had to be performed without the aid of pencil and paper, and only the final answer to each item was noted on the test sheet. The score was the number of correctly solved items.
Fig. 2,A shows that performance in the single-conflict task (Group I) and the doubleconflict task (Group 11) did not differ markedly. Group I had 70 percent correct responses and Group I1 66 percent. Thus, performance appeared to be unaffected by the additional demand imposed by the conflicting auditory stimuli.
March. 1976
Journal of Human Stress
17
TASK DEMAND AND AROUSAL
S i n g l e - c o n f l i c t task Ooublc - c o n f l i c t t a s k M e n t a l arithmetic task
1000 ln
500
A
ln
0,
In
m
c
C
E
ul
900
400 ln
t
E c
c
U
U
E
al
800
300
-
-
k 700
k 200 n
0
0
U
U
Downloaded by [New York University] at 01:28 05 June 2015
0
.
B
a 8
0
n
E
E
z
Z
5
3
100
600 Group I
11
Group I
II
111
Fig. 2. Means and standard errors for performance in a color-word task performed under single-conflict and doubleconflict conditions (Diagram A). and in an arii hmetic task (Diagram B).
Fig. 2,B shows that scores in the subsequent mental-arithmetic task were nearly the same in Groups I, 11, and 111, indicating that the conflict tasks did not leave marked aftereffects on performance. Catecholamine Excretion
Table 1 shows means and standard errors lor adrenaline and noradrenaline excretion in Group I, exposed to the single conflict; in Group 11, exposed to the double conflict; and for ;all subjects in the control condition. The values from the control condition were consistent with those from previous investigations," adrenaline output increasing betweten morning and noon, and noradrenaline output showing minor random fluctuations. Single- and double-conflict tasks both induced marked rises in adrenaline excretion; after the latter, adrenlaline remained on an elevated level during the arithmetic task. Noradrenaline excretion was not systematically affected by either conflict task. This greater sensitivity of adrenaline than of noradrenaline output to psychological stress has been clearly documented in previous re18 Journal of Human Stress
search. l 2 The data were analyzed statistically by applying t-tests to mean intra-pair differences in values for adrenaline excretion obtained at the same points in time under control and experimental conditions. It was shown that the rise in adrenaline excretion induced by the double-conflict task was statistically significant both during the conflict task and during the subsequent arithmetic task (t = 5.30 and 4.70, respectively; df = 15, p
Journal of Human Stress Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/vzhs20
Task Demand as Reflected in Catecholamine Excretion and Heart Rate a
Dr. Marianne Frankenhaeuser Ph.D. & Dr. Gunn Johansson Ph.D. a
Department of Psychology , University of Stockholm. Experimental Psychology Research Unit of the Swedish Medical Research Council , USA Published online: 09 Jul 2010.
To cite this article: Dr. Marianne Frankenhaeuser Ph.D. & Dr. Gunn Johansson Ph.D. (1976) Task Demand as Reflected in Catecholamine Excretion and Heart Rate, Journal of Human Stress, 2:1, 15-23, DOI: 10.1080/0097840X.1976.9937485 To link to this article: http://dx.doi.org/10.1080/0097840X.1976.9937485
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://www.tandfonline.com/page/termsand-conditions
TASK DEMAND AS REFLECTED IN CATECHOLAMINE EXCRETION AND HEART RATE
Downloaded by [New York University] at 01:28 05 June 2015
MARIANNE FRANKENHAEUSER, Ph.D., and GUNN JOHANSSON, Ph.D.
Immediate qffects and aftereffects of exposure to a color-word conflict task were studied in two groups 6f subjects, one of which petjiormed the task without auditory interference (“single conjlict*’), the other with auditory inteflerence (“double conflict”). Physiological arousal indices were more susceptible than performance measures to the level of task demand. Thus. the higher demand imposed by the double-conflict tusk was reflected in relatively larger increases of adrenaline excretion and heart mte, both during the conflict task and during the subsequent arithmetic task, whereas the performance measures remained unaffected. INTRODUCTION Many of the demands to which individuals living in technologically advanced societies are subjected relate to various forms of stimulus overload.’ One typical feature of today’s psychosocial environment is quantitative overload: another is qualitative overload.2 The former refers to the intensity and frequency of the stimuli impinging on the individual, while the latter refers to their complexity, novelty, incongruity, and a m b i g ~ i t y . ~ The concept of overload is based on the general notion of the organism’s limited capacity to handle incoming signals. On the physiological level, overload commonly is reflected in cortical, autonomic, or endocrine indices of arousal. On the cognitive level, increased effort ~
Both authors are affiliated with the Department of Psychology, University of Stockholm. Dr. Frankenhaeuser is Professor and Head of the Experimental Psychology Research Unit of the Swedish Medical Research Council; Dr. Johansson’s research is sponsored by the Swedish Work Environment Fund, and she is the research administrator of the Bank of Sweden Tercentenary Foundation’s Committee on Man and Working Life.
March. 1976
is the typical response to ~ v e r l o a dthis ; ~ often is accompanied by feelings of distress, irritation, and rush. On the whole, behavioral measures (e.g., task performances) appear to be relatively less sensitive, tending to remain unaffected under stimulus conditions which upset the subject’s physiological and subjective balance. The resistance of performance to overload has been interpreted in terms of compensatory adaptive reactions which are called into play during short-term stress and which tend to obscure harmful stress reactions by helping the individual to “pull himself together.”s Lately, attention has been drawn to possible negative aftereffects arising from intense efforts to cope with acute demands.6 Such a “cost of adaptation” may manifest itself ajier the termination of the stressor, in performance decrements, annoyance reactions or in heightened physiological arousal. When long-lasting and intense, aftereffects are likely to add to the wear and tear of the organism. Therefore, an important problem in stress research is to examine the duration of the various changes induced by demands of different kinds and intensities. In the present investigation, subjects were studied during and after exposure to a colorword conflict task (based on the Stroop test) representing two levels of demand on their capacity for sustained performance under distracting conditions. Catecholamine excretion, heart rate, and subjective reactions were used as indices of the effort required to perform the task under the two conditions. It was assumed that the more intense effort induced by the more demanding version of the conflict task would be reflected, not only in more pronounced psychophysiological changes during exposure to the stressor, but also in a slower return to physioJournal of Human Stress
15
TASK DEMAND AND AROUSAL logical and subjective baselines as well as in impaired performance on a subsequent arithmetic task.
The subjects of the two groups were matched for baseline levels of adrenaline excretion, determined by calculating the means for three values obtained in the control session (2.7+ 0.6 ng/min for Group I, and 2.6 +- 0.6 ng/min for Group 11). The control session also served as a check on the diurnal variation in catecholamine excretion. Group I11 attended one session only, in which mental arithmetic was performed. In this case, the arithmetic task was not preceded by the conflict task, and the arithmetic scores were used to assess possible aftereffects on performance. Experimental and control sessions took place between 8:30 a.m. and 1 p.m., each session consisting of three 70-min periods separated by 15-min intervals. The subjects had been asked not to eat before arriving in the laboratory, and they were served a light breakfast before the session started. A short interview was held in which each subject was asked about his general state of health, etc. He was then asked t o void before starting the session. In each interval the subject drank a glass of water to secure prompt micturition, and ate a piece of bread and butter in order to prevent hunger reactions from affecting
METHODS
Downloaded by [New York University] at 01:28 05 June 2015
Subjects, Design, and Procedure
Three groups of 16 subjects each participated in the investigation. Their ages ranged from 19 to 36 years (mean 24.3), their body weights from 51 to 90 kg (mean 71.21, and their heights from 160 to 195 cm (mean 181.6). The subjects of Groups I and 11 first had an introductory session (to be informed about the procedure and to get acquainted with the experimental setting), then a control session and an experimental session of about 4.5 hours each (Fig. 1). The control session was spent in the same way by all subjects - i.e., relaxing, reading, and listening to the radio. In the experimental session, Group I was exposed to a color-word task denoted "single conflict" and Group I1 to the same task with interfering auditory stimuli, denoted "double conflict." In both groups the conflict task was followed by a period of mental arithmetic and an inactivity period.
B r e a k f a s t + interview S i n g l e - c o n f l i c t task D o u b l e con f l i c t t a s k Arithmetic task inactivity
-
I
0
"
~
40
~
80
"
120
"
'
160
~
200
"
'
2LO
Time i n minutes
Fig. 1. Design of experiment.
16 Journal of Human Stress
March. 1976
FRANKENHAEUSER and JOHANSSON the variables to be examined. The control session was spent by the subjects in pairs; the experimental session was carried out individually except for the first period, to which the subjects came in groups of two-six.
Downloaded by [New York University] at 01:28 05 June 2015
”Single” and ”Double” Conflict Tasks
The conflict task was modelled on Card CW of Stroop’s’ color-word test. In essence, the test material consists of color words (red, blue, yellow, green) which are printed in different colors, the combination of words and colors being incongruent; for example, the word yellow may be colored red, etc. The subject’s task is to ignore the word and name the color of the print. The Stroop test has been modified in our laboratorys for use in a group situation. Two forms have been designed which represent different levels of task demand, the single-conflict task and the double-conflict task. In the former, color words are projected on a screen, one at a time, from a 16 mm film, and the subject has to respond to each word by marking the correct word on a response sheet with consecutively numbered rows; corresponding numbers are presented on a sound track synchronously with the visual stimuli in order to help the subject orient himself to the right row on the sheet. In the latter task, auditory stimuli are added by pairing the visually presented color word with an incompatible color word presented simultaneously on the sound track. Each task comprised 30 blocks of 21 stimuli each. The task proper was preceded by instructions and practice. The duration of the stimuli varied randomly from .4 - 1.0 sec. They were presented in random order at random intervals of .8 - 1.7 sec. The score was the-number of correct responses.
Catecholamine Excretion
In the introductory session the subjects had been informed about the factors that might affect catecholamine-excretion rates and which had to be avoided prior to experiments, e.g., intake of alcohol, drugs, and caffeine-containing beverages, smoking, strenuous exercise, etc. Urine samples were collected after each of the three successive periods in the experimental session. The urine volume was measured and pH adjusted to about 3 with 2 N HC1. The samples were stored at -18’ C until analyzed by the fluorimetric technique of Euler and Lishajko. Heart Rate
During the experimental session heart rate was monitored continuously by an electronic pulse-meter (San-Ei PM 101). Five readings were made at 10-min intervals within each period. For technical reasons heart rate was not measured in the control session. Instead, baseline levels were obtained by instructing the subjects to measure their pulse rate themselves by palpation of the radial artery upon rising in the morning; the score for each subject was the mean of two measurements taken on each of two consecutive days. Subjective Variables
After each period in the experimental session the subjects made self-estimates of different aspects of wakefulness and mood (e.g., “alertness,” “distress,” “irritation”). Ratings were made on graphic scales (120 mm), the endpoints representing the highest and lowest intensity that the subject ever had experienced in terms of each variable. The score was the distance (in mm) from the low-intensity endpoint. RESULTS
Mental Arithmetic
Performance
The mental-arithmetic test (Norinder, unpubl.) consisted of a series of 1-digit items arranged in pairs. The task was to add and subtract numbers according to certain rules. All operations had to be performed without the aid of pencil and paper, and only the final answer to each item was noted on the test sheet. The score was the number of correctly solved items.
Fig. 2,A shows that performance in the single-conflict task (Group I) and the doubleconflict task (Group 11) did not differ markedly. Group I had 70 percent correct responses and Group I1 66 percent. Thus, performance appeared to be unaffected by the additional demand imposed by the conflicting auditory stimuli.
March. 1976
Journal of Human Stress
17
TASK DEMAND AND AROUSAL
S i n g l e - c o n f l i c t task Ooublc - c o n f l i c t t a s k M e n t a l arithmetic task
1000 ln
500
A
ln
0,
In
m
c
C
E
ul
900
400 ln
t
E c
c
U
U
E
al
800
300
-
-
k 700
k 200 n
0
0
U
U
Downloaded by [New York University] at 01:28 05 June 2015
0
.
B
a 8
0
n
E
E
z
Z
5
3
100
600 Group I
11
Group I
II
111
Fig. 2. Means and standard errors for performance in a color-word task performed under single-conflict and doubleconflict conditions (Diagram A). and in an arii hmetic task (Diagram B).
Fig. 2,B shows that scores in the subsequent mental-arithmetic task were nearly the same in Groups I, 11, and 111, indicating that the conflict tasks did not leave marked aftereffects on performance. Catecholamine Excretion
Table 1 shows means and standard errors lor adrenaline and noradrenaline excretion in Group I, exposed to the single conflict; in Group 11, exposed to the double conflict; and for ;all subjects in the control condition. The values from the control condition were consistent with those from previous investigations," adrenaline output increasing betweten morning and noon, and noradrenaline output showing minor random fluctuations. Single- and double-conflict tasks both induced marked rises in adrenaline excretion; after the latter, adrenlaline remained on an elevated level during the arithmetic task. Noradrenaline excretion was not systematically affected by either conflict task. This greater sensitivity of adrenaline than of noradrenaline output to psychological stress has been clearly documented in previous re18 Journal of Human Stress
search. l 2 The data were analyzed statistically by applying t-tests to mean intra-pair differences in values for adrenaline excretion obtained at the same points in time under control and experimental conditions. It was shown that the rise in adrenaline excretion induced by the double-conflict task was statistically significant both during the conflict task and during the subsequent arithmetic task (t = 5.30 and 4.70, respectively; df = 15, p
