As office machinery is introduced, the number of routine jobs is increased and consequently the proportion of 'positions requiring initiative' is decreased. 'Mechanization is resulting in a much clearer distinction between the managing staff and the operating staff,' observed the War Manpower Commission. 'Finger dexterity is often more important than creative thinking. Promotions consequently become relatively rare. . . Some large office managers actually prefer to hire girls who are content to remain simply clerks, who will attempt to rise no higher than their initial level' (White Collar: The American Middle Classes, 1951, pp. 205-206).