Peter Warr identified 2 types in his model:
1) Vitamin A-like factors: An excess of these factors does not add additional benefits, and sometimes can be harmful.
Example: job security; Its presence in a minimum amount is necessary, but its excess (very routine and reliable work) can cause boredom or loss of interest.
2) Vitamin C-like factors: the stronger the effect of these factors, the stronger their positive effect, while they do not cause harm.
Example: appreciation and social support; The higher the level, the greater the satisfaction and psychological well-being.