Author Paul Kenyon
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Coping with Stress
|Many people claim that
they find their working lives stressful. Indeed the 'executive
lifestyle' has often been linked to higher than normal levels of
stress. In part this is because of a famous experiment entitled "Stress
in Executive Monkeys" carried out in the 1950s by Joseph
Brady found that monkeys who pressed a lever on an operant schedule (worked) to avoid electric shock, died from ulceration. In contrast, ‘yoked’ subjects - monkeys that got the same amount of shocks as their worker companion but who did not have to work on the schedule - did not ulcerate.
Brady's experiment has entered popular culture, but it is probably a myth. The results are probably an artifact caused by inadequate experimental design. It appears that the monkeys in the experiment were not randomly assigned to ‘executive’ and ‘yoked’ treatments.
It can be difficult for an animal to learn a new operant response to avoid shock. Brady's monkeys had to learn that pressing a lever was the required response. Consequently,
- monkeys who were able to learn to avoid shock were assigned to the executive group
- monkeys who failed to learn were put into the yoked condition.
The effects of 'control'
on ulceration in rats
In 1971 Weiss repeated Brady’s experiment using rats. He used a specially constructed narrow testing box which was equipped with a paddle that a rat could operate with its paws. Shock was delivered through tail electrodes so that the animal could not adopt postures that alleviated the effect of foot shock. He examined the effects of various psychological factors on the development of stomach ulcers - a measure of stress.
Weiss examined the effect of control on the stress response. For example, if you find the prospect of failing an exam stressful, writing a good exam paper is a coping response you can use to control the situation. You can avoid failure by writing a good answer.
Weiss varied the amount of control that rats had in a stressful situation using the following design:
Groups of subjects were run in triplets. Within each triplet of three rats:
|Rat 1 put into apparatus but received no shock. Therefore the amount of stress exhibited by this rat is a measure of the stressfulness of being constrained in the test apparatus.||Rat 2 could avoid and escape shock by pressing lever. Therefore this rat can use a coping response to control shock delivery.||Rat 3 yoked to Rat 2 received shock when Rat 2 failed to emit an avoidance or escape response. Rat 3 could not avoid or escape shock by pressing the lever. Therefore this rat has no control over the stressor.|
|Note that rats 2 and 3 receive exactly the same amount of physical stressor -shock- because they are 'yoked' together|
The stress response of the yoked rat is of critical importance in this experiment. How will it react to being in an uncontrollable situation? In terms of our exam paper example, the yoked rat is in the bizzare situation of a student whose exam mark does not depend on how well they answer the exam questions. Instead their mark is exactly the same as that given to the person sitting beside them in the examination room!
Rats in the 'No shock' control group showed a small amount of ulceration.
Rats that were able to use a coping response to control shock showed an intermediate stress response.
The important finding is that rats with no control over shock delivery had significantly greater stomach ulceration than rats that received exactly the same amount of electric shock but were able to avoid or excape from it.
Because the yoked group experienced the same amount of physical stressor (shock) as the avoidance/escape group, a psychological factor - lack of control over the situation - must be responsible for difference between these groups.
In terms of our human example, it would be much more stressful if you failed an exam on account of the poor performance of the student sitting next to you, than if you failed on account of your own poor answers.
The effects of 'predictability' on
ulceration in rats
In a separate experiment, Weiss examined the effect of predictability on ulceration. If you find exams stressful, would you prefer advance warning of the exam date? Imagine a situation in which half the class knew the exam date, but it was a secret for the other students. What group would you prefer to be in?
Weiss investigated the impact of predictability on the stress response using the following design:
|Rat 1 put into apparatus but received no shock||Rat 2 received a warning signal before shock.||Rat 3 yoked to Rat 2 received no warning signal before shock.|
Rats in the 'No shock' control group showed a small amount of ulceration.
Rats given signalled shock had an intermediate amount of ulceration.
Rats that were unable to predict impending electric shock showed significantly greater stomach ulceration that rats that received exactly the same amount of electric shock but were warned that it was about to be delivered
Because both the yoked groups experienced the same amount of psysical stressor (shock), a psychological factor - predictability must be responsible for difference between these groups.
In terms of our example, it would be more stressful if the date of examinations was kept secret.
The relationship between response rate and stress
There is a third factor that has an important impact on the intensity of an individual's stress response. Weiss recorded the total number of responses made by rats in these experiments. Now a rat placed on an signalled avoidance schedule only needs to make an avoidance response when the warning signal comes on. Any extra responses made in the absence of the warning signal have no programmed consequences - they do not affect the delivery of shock. But rats on these schedules often make several 'inter-trial' responses. Yoked rats can also make operant responses, but of course none of their responses effect shock avoidance.
Weiss examined results from all his subjects and found that response rate effected ulceration. The more responses the animal made the greater was its ulceration. By matching data from high responding rats that that were able to avoid shock with data from yoked rats that emitted very few responses he was able to show Brady’s executive monkey effect.
These results suggest
- that trying to cope in uncontrollable situations may make things worse in terms of your stress response
- doing too much coping in a controllable situation may also damage your health
In other words 'running around like a headless chicken' may be bad for your health!
The relationship between feedback and
Another factor identified by Weiss that inflences our response to stress is the feedback we get from the environment in response to our attempts to cope. For example, imagine that you are taking the driving test. If you pass, the examiner will allow you to have a full drivers' licence which allows you to drive on your own without a qualified driver in the car. In the British version of these tests you get into the car with a 'stony-faced' examiner who issues a series of instructions "Carry out an emergency stop when I hit the dashboard with my clipboard", "Reverse the car around this corner", "Park the car between those two stationary cars" etc. You carry out each task without any indication from the examiner as to how well you are doing. You role is to avoid failing the test, but you get no feedback from the examiner as to your success. Very stressful ...
Weiss showed that relevant feedback reduces the impact of a stressor . In this experiment feedback refers to the signal that follows a response. In an avoidance situation with light as the warning signal, the light going off is relevant feedback which tells the rat that it is now in a safe situation.
Weiss showed that ulceration was reduced if an avoidance response produced a 'safety' signal
An even more stressful situation involves negative feedback. This is a situation in which you find yourself in circumstances where 'the rules of the game have changed'. This can happen in business where the boss decides that the company needs to change direction and the workers either don't understand, agree or have the skills to adapt.
Imagine that you work for a company selling home furnishings, and you specialise in wallpaper. But the company has decided that it wants to concentrate on selling paint. Every time you tell your boss that you have sold more wallpaper he gets annoyed and threatens you with the sack. You are in a negative feedback situation - the response you used in the past to avoid loss of your job is now putting you in the very situation you are trying to avoid. This turns out to be the most stressful situation of all ....
The diagram shows that negative feedback - in which the avoidance response actually switches the shock on - produces severe ulceration.
Weiss' theory of stress
In the light of these results Weiss developed a three dimensional theory of the relationship between responding, feedback and ulceration.
- For a given level of feedback, the more responses the subjects emits the greater the amount of ulceration.
- For a given number of responses, the less relevant the feedback, the greater the amount of ulceration.
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