PSYCHOLOGY OF MENTAL DEFICIENCY 



89 



Fig. 



An Experiment in Action with the Ergograph. 



Mental Age Capabilities ('lass 



8 years, Errands. Light work. Makes beds. jj Low 



9 years, Heavier work. Scrubs, mends, lays bricks, 



cares for room with simple furniture. 



10 years, Good institution helpers. Eoutine work. Middle 



11 years, Fairly complicated work with only occa- 



sional oversight. 



12 years, Uses machinery. Cares for animals. No 



supervision. Can not plan. High 



.Moron. 



HI 



un 



a 



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 volun- 

 tary control. 



