PSYCHOLOGY OF MENTAL DEFICIENCY
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Mental Age | Capabilities | Class | ||
8 years, | Errands. Light work. Makes beds. | Low | Moron. | |
9 years, | Heavier work. Scrubs, mends, lays bricks, cares for room with simple furniture. | |||
10 years, | Good institution helpers. Routine work. | Middle | ||
11 years, | Fairly complicated work with only occasional oversight. | |||
12 years, | Uses machinery. Cares for animals. No supervision. Can not plan. | High |
![](http://upload.wikimedia.org/wikipedia/commons/thumb/a/a7/PSM_V79_D093_Ergograms_of_a_normal_man_and_a_mentally_defective_boy.png/510px-PSM_V79_D093_Ergograms_of_a_normal_man_and_a_mentally_defective_boy.png)
Figs. 8 and 9. Ergograms. Records of a normal man and of a defective boy, the latter showing characteristic irregularities.
The ergograph was devised by Mosso, an Italian psychologist, and is used to measure muscular fatigue. A weight is lifted with one finger every alternate second until the muscle is tired out. Each lift is recorded on a vertical line and the sum total of lifts and lengths of lines are indicative of muscular action and voluntary control.