240 KANSAS UNIVERSITY SCIENCE BULLETIN. 



period ; then grew weak and numb." "Shoulders felt sore. 

 General tension all over. Cobwebs seemed cleared away in 

 second test." "Mind seemed clear at the beginning of second, 

 test, then felt a tendency to confusion. Felt drowsy in second 

 half of the test. Legs tingled and hips ached." "Mind clear at 

 first; then a tendency to sleep. Muscles of whole body seemed 

 to be relaxing. Were tense at first." "Felt sleepy all over, i. e., 

 numb and quivery, particularly in legs. Could read the syl- 

 lables easily, and mind seemed fairly clear, but the syllables 

 seemed to make little impression." It will be seen that fre- 

 quently the subject feels stirred up and active after the physi- 

 cal work. Or he may start the second test in that condition 

 and then he notices the coming on of drowsiness and the gen- 

 eral relaxation of the muscles. Sensations of strain have given 

 way to sensations of relaxation or of rest, which seems to con- 

 stitute the feeling of fatigue. 



Shepard (35) suggests that "the content of sleep consists of 

 a group of sensations of 'fatigue' or 'rest.' Sleep is a more 

 complete rest. The process is a dominance of an organized 

 group of these sensations. Such sensations from one part are 

 associated with those from another. It is not that the sen- 

 sations are aroused only at the time of sleep, of course, but that 

 they become dominant in attention as any other group of sensa- 

 tions may be dominant in attention. This dominance is pro- 

 moted by the intensity of the sensations themselves and by 

 other conditions of attention." (p. 78.) This relation of the 

 sensations of fatigue or relaxation to the mental condition is 

 seen in the introspections. One subject reported that the 

 arms seemed rigid, and so long as this condition of strain en- 

 dured he was mentally alert. At least he experienced no tend- 

 ency to drowsiness. We simply can not sleep when the sensa- 

 tions of strain dominate. But as the muscles begin to relax, 

 drowsiness and consequent confusion result. 



There remains the difference in the character of the results 

 with the first two tests as compared with the last two tests to 

 be considered. This difference can be accounted for by the 

 effect of incentive. It is doubtful whether we ever do our best 

 unless there is present something more than the vague purpose 

 to do our best. A runner can run a little faster in a contest 

 than he can alone, however hard he may try. Wright (47) 

 found that a subject could do considerably more on the ergo- 



