The personalities of 100 mechanical engineers were investigated by means of protective techniques, a personality inventory, a personal history form, and a clinical interview. While they show a wide range of temperamental variation, there are definite trends which characterize the main body of mechanical engineers.

(1) Mechanical engineers are emotionally stable. They ordinarily make compatible marriages, maintain comfortable human relations, and are usually free of neurotic and psychosomatic symptoms. (2) Interpersonal relations are harmonious but casual. Impersonality is one of their more common traits. (3) An analytical interest in people is rare. (4) They avoid introspection and self-examination. Insight is often shallow. This lack of self-understanding makes them less perceptive of social nuances and relatively insensitive to the less obvious needs of others. (5) Engineers are straightforward, direct, and self-sufficient. (6) They are inclined to be matter-of-fact and, outside their own field, are often unimaginative. Their attitudes are realistic, though their brand of realism deals more with surfaces than with depths. (7) Engineers are energetic. When faced with problems, they are advocates of the direct action approach. Polite diplomacy and oblique conciliatory tactics are foreign to their nature. (8) Most of them are goal-oriented, serious-minded, and conscientious. (9) They like phenomena to be definitely structured; there is a fundamental aversion to ambiguity. This fondness for structure and order may underline their essentially authoritarian approach. (10) Engineers have definitely masculine traits and interests. (11) Social participation is normal in amount. The explanation is more a matter of conventionality and social conformity than any profound interest in people. It is not true that engineers are usually introverts. What sometimes makes them appear so is their characteristic impersonality.