This paper presents a cognitive activation theory of stress (CATS), with a formal system
of systematic definitions. The term ‘stress’ is used for four aspects of ‘stress’, stress stimuli,
stress experience, the non-specific, general stress response, and experience of the stress
response. These four meanings may be measured separately.
The stress response is a general alarm in a homeostatic system, producing general and
unspecific neurophysiological activation from one level of arousal to more arousal. The stress
response occurs whenever there is something missing, for instance a homeostatic imbalance,
or a threat to homeostasis and life of the organism. Formally, the alarm occurs when there is
a discrepancy between what should be and what is—between the value a variable should have
(set value (SV)), and the real value (actual value (AV)) of the same variable. The stress
response, therefore, is an essential and necessary physiological response. The unpleasantness
of the alarm is no health threat. However, if sustained, the response may lead to illness and
disease through established pathophysiological processes (‘allostatic load’).
The alarm elicits specific behaviors to cope with the situation. The level of alarm depends
on expectancy of the outcome of stimuli and the specific responses available for coping.
Psychological defense is defined as a distortion of stimulus expectancies. Response outcome
expectancies are defined as positive, negative, or none, to the available responses. This offers
formal definitions of coping, hopelessness, and helplessness that are easy to operationalize in
man and in animals. It is an essential element of CATS that only when coping is defined as
positive outcome expectancy does the concept predict relations to health and disease.
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