Abstract
The effects on performance are discussed of various types of stress deriving from imbalance between capacity on the one hand and, on the other, the demands of tasks, environmental conditions and social situations which either overload or underload the individual. Common cybernetic principles seem to apply over an area which includes not only stress, but also motivation and arousal. A model is proposed which ties together three previously existing models current in this field: the Inverted-U Hypothesis, Signal Detection Theory and the Yerkes-Dodson Law. The model is examined further in relation to individual differences of personality and to problems of conserving talent among students and those carrying heavy executive responsibility.