234 IOWA ACADEMY OF SCIENCE Vor.. XXVII, 1920 
as to the placing of an individual in a group — regarding quick- 
ness of action, 
2, It is impossible to predict from one or two motor tests how 
a subject will rank in his group as to individual variability (con- 
stancy) in other motor tests. At least the M.V. shows up to be 
a fleeting factor from test to test. Either the M.V. is not a minute 
enough measure of individual variability or no personal equation 
exists in this respect. The negative outcome ought to have the 
greatest bearing on vocational motor testing. 
A wealth of other significant general and special results, which 
lack of space forbids stating in full here, also were evolved from 
the above investigations. 
It may suffice to note, as a matter of general interest, that re- 
garding the highest rate of movement for the different bodily 
members, we get the following sequence: 
(1) lips, (2) index finger, (3) jaws, (4) thumb (grip), (5) 
elbow, (6) foot, (7) head. 
As to the range of different bodily reactions, we may state that 
the individual’s variation from the average of the group is very 
nearly proportional to the personal range in M.V. for all parts of 
the body here tested except the jaws. The rate of the quickest bite, 
then marks out the individual most clearly in the group. 
SERIAL ACTION AS A BASIC MEASURE OF MOTOR 
CAPACITY 
C. FREDERICK HANSEN 
Motor tests involving ‘‘continuous discriminative reactions” or 
“serial action” are being standardized by the psychologist with 
the end in view of reproducing, in dealing with his practical 
problems, the actual conditions of simple daily motor activities 
more closely than obtained in the traditional reaction time tests. 
These newer measures of motor capacity recognize the essentially 
fluid character of stimuli and reactions their fundamentally 
continuous interplay, which is apparent not only in simple motor 
achievements like walking or handling tools, but also in the com- 
plex activities of the musician, the telegrapher, the typist, or the 
expert mechanician. In the analysis, therefore, of motor capaci- 
ties for clinical, vocational, or industrial purposes, the performance 
of a subject in a standardized test of serial action may serve as an 
index of his basic motor capacity, applicable to many problems. 
