Until the end of the years 1970, research on psychosocial factors was still blurred and offered a variety of factors that could be a source of discomfort at work: workload, responsibility, role conflict, insecurity of employment… It was in this context of ignorance that in 1979, Robert Karasek, an American sociologist and psychologist, proposed a model that had the quality of being able to model all these factors in order to facilitate their understanding.
This very popular model has been subject to many studies. They demonstrate the predictive validity of the model for cardiovascular diseases, mental pathologies, or global health indicators such as perceived health, quality of life or absenteeism for health reasons.
The two variables of the model
Psychological demand or demands
Job demands, the concept of demand appears in the years 1970. Karasek defines them as ” psychological stressors involved in the realization of workload, stressors related to unexpected tasks and stressors arising from personal conflicts at work “. This concept takes into account both the amount of work to be done, the level of concentration needed and the time constraints related to work.
However, for Karasek, provided that the person has sufficient decision-making latitude, the person will be able to actively channel their energy and limit the adverse effects of these requirements.
The decision latitude
The second dimension of the model, also called “control“, is the decision latitude. It refers to both the decision-making autonomy and the use of the skills or its creativity to carry out its work.
The correlation between decision-making latitude and standardization is noted here. Key tool of Lean, it is good to remember that the level of standardization is built with the teams. Excessive standardization is counterproductive. The Karasek model can be helped to identify the right level.
Interpretation of the model
Of these two variables, Karasek1 offers a two-dimensional matrix, thus determining 4 typical work situations:
- Low Tension : this first situation is the intersection of low work requirements and of an important decision-making latitude. The atmosphere is relax and the subject in good working conditions.
- Passivity: this second situation is the crossing of low requirements and low latitude. The subject is passive, little interested in his work and unmotivated.
- High tension: this third situation is the crossing of high demands with a low decision-making latitude. The subject is stressed and in poor working conditions. This is a critical situation that Karasek calls ” High Strain Jobs “.
- Activity: Finally, the last situation is the crossing of strong demands and a strong decision-making latitude. It is characterized by well-being and the desire to learn.
It should be noted that according to Karasek, work-induced behaviour and attitudes are found in personal life. He finds a link between ” active ” jobs and political activity or even recreation. On the contrary according to Karasek, passive subjects learn to do nothing more to undertake and behavior is found in the sphere of leisure and social activities.
A few years later running 1980, a pupil of Karasek, Johnson2 integrated A new dimension, social support. This new model suggests that employees who are well-placed in a working group, combine their resources to cope with stressors: at the most one person will have support and assistance from other people, at the most it will be able to cope with the stressors . It acts as a modulator of the effects of the two preceding parameters: either it tempers them or it accentuates them. Johnson defines the term “Iso-strain” to characterize a situation that accumulates High-Job-strain and isolation.
The questionnaire (see detail in the Excel file on your left) consists of 26 questions. The first 18 (9 for decision latitude and 9 for psychological demand) were those of the initial model and the last 8 were those related to social support. Each question is evaluated according to the Likert scale:
- not at all agree: 1 to calculate the score
- not agree: then count 2
- Okay, then count 3
- totally agree: then count 4
For the decision latitudeaxis, it was determined through the Sumer 2003 survey, a critical threshold of 71. Below this threshold, people are considered not to have enough latitude and become passive.
For the psychological demandaxis a threshold of 20 was set. Above this threshold, the person is subject to more and more constraints and becomes more and more tense.
For the social supportaxis, the threshold is set at 24 below which the person is to be considered as being poorly supported.
1-R. A. Harasek (1979) – Job demands, job decision, Latitude and mental strain: implications for job design
2 – J. V. Johnson (1986) – The Impact of workplace and social support, job demands and work control upon cardiovascular disease in Sweden
G. Chandra (2009) – Cognition, health and daily life