The tremor of the left forefinger, the galvanic skin reflex (GSR.), and the pulse were recorded simultaneously on a moving strip of bromide paper, while each of 5 subjects reacted to the 4 situations: muscular work, mental work, reaction time tests, and sudden noise. Pulse rate did not vary consistently. The amt. of tremor rose rapidly immediately after a loud noise or stimulus for a reaction by the right hand. The rise followed with some latency the request to squeeze a hand dynamometer with the right hand. During mental multiplication the amt. of tremor decreased somewhat and then rose above the resting level just before the answer was given. In these 4 situations the skin resistance decreased rapidly about 2 secs. after the 1st stimulus. The tremor appears to be independent of the GSR and will probably prove to be more satisfactory for diagnosing mental states, since it varies in more different ways with the situation.