A general statement may be deduced that, for lines of 10 mm. in length, there is no difference in either mean or constant errors, when a weight is imposed to cause retardation, provided the weight is not large enough to cause pain or fatigue.
By separating the averages for right- and left-handed subjects, it may be further said that:
Visual control is not efficient to reduce the error and no particular gain in regularity can be noted. The left-handed subjects show, for the left hand, much better results without visual control as far as the free motion is concerned.
While somewhat contradictory, it may be stated that constant errors are reduced by the weight addition, and there is some evidence leading to the belief that the ruled line is shorter when the weight acts as a retarding influence.
INDIVIDUAL RECORDS
Considering lines 10 mm. long with a retarding weight:
A glance over the seven individual records shows some considerable increase in both constant- and mean-error irregularities, as compared with the free-motion curves, as well as in actual errors; there are distinct losses of volitional control for both classes of errors, especially at or near the ends of the series.
There are cases of very low mean error to be found on all records, where the value is 1/4 mm. or less, and, while the same phenomenon is found with free motion, it is more marked here and occurs more frequently; in most cases it seems as a drop from errors of larger values rather than a gradual matter, as if the subject realized the large error and exerted unusual volitional control to correct and produce a very accurate record, but found that the attention needed was beyond his will-power, as shown by the immediate lapse of accuracy.
There is an indirect confirmation of this view from the introspective testimony of the subjects.
The visual element steadies but does not reduce mean errors when weight is retarding.