These experiments have been conducted to test sensory discrimination, precision of motor response and some of the simpler types of judgment, such as those involved in the solution of simple puzzles with blocks, matches, etc. The fact of the negligibility of sex difference with regard to certain minor measurable traits has been adequately demonstrated by a wide variety of experiments. The fact of sex equality or mental capacity has been less accurately but fairly universally noted by popular consensus of observation and opinion of the work of women in the various trades and professions. There are differences between men and women in physical strength and in consequent susceptibility to fatigue. These are important considerations in qualifying the amount of work a woman can do as compared with that of a man, and have justly resulted in the regulation of hours for women, as a special class. But there do not seem to be, on the average, significant original differences in mental capacity.[3] [Footnote 3: On this subject there has been collected a large amount of accurate experimental data. See Goldmark: _Fatigue and Efficiency_, part II, pp. 1-22. These refer to physiological differences.] There do exist, as a matter of practical fact, some of the special attributes commonly ascribed to the masculine and feminine mental life, but it is generally agreed by investigators that these are to be accounted for by the different environment and standards socially established for men and for women. There are radical and subtle differences in training to which boys and girls are subjected from early childhood. There are deeply fixed traditions as to the standards of action, feeling, and demeanor to which boys and girls are respectively trained and to which they are expected to conform. If a boy should not live up to this training and expectation, he may be marked out as "effeminate." If a girl does not conform, she is defined as a "hoyden" or a "tomboy." These social distinctions, which are emphasized even in the behavior of young boys and young girls, grow more pronounced as individuals grow older. One need hardly call attention to actions regarded as perfectly legitimate for men which provoke disapproval if practiced by women. Rigid training in these different codes of behavior may cause acquired characteristics to seem inborn. But whether these general features commonly held to distinguish the mental life of man or woman are or are not intrinsic and original, they have been marked out by certain investigators as socially fundamental. Thus Heymans and Wiersma, two German investigators, set down as the differentia of feminine mental life (1) greater activity, (2) greater emotionality, (3) greater unselfishness of the female.[1] [Footnote 1: See Thorndike's _Educational Psychology_ (1910), p. 136.]