PERCEPTION OF RESISTANCE. 



The following fractions express the results of actual observations 



1023 



In comparing a weight — -the so-called "standard weight" — with others, 

 it is not a matter of indifference whether the lifting of the standard precede 

 or follow that of the weight to be judged against it. Hence the well-known 

 "time error." There is a tendency to undervalue the succeeding weight of 

 the pair. This tendency is stronger with shorter intervals between the 

 successive lifts than with longer, and with heavier weights than with lighter. 

 It appears when the comparison is between right and left hand lifts, though 

 not so markedly as with lifts confined to right or left alone. Fatigue affects 

 the time error in the direction of reducing it. An explanation offered for the 

 time error is that, especially when the successive lifts follow each other 

 rapidly, the motor organs are still in some degree of excitement, or at any rate 

 the path is smoothed and favourably prepared for repetition, when the second 

 impulse to lift occurs ; hence more innervation is employed than is intended, 

 and the weight is judged to move more easily. That it occurs with alternate- 

 handed experiments is one more instance of the smoothing a motor path on 

 one side by use of the symmetrical motor path on the opposite, e.g. of the 

 collaboration of right and left hemispheres. On this view of the causation of 

 the time error the effect of fatigue is obvious. There is also a spatial error. 

 The weights to be lifted cannot be so placed as to lie to hand in quite the 

 same manner. The difference of the position from which the weight is to be 

 picked up exerts a complex influence. 1 



Discrimination is usually sharper when weights are compared in ascend- 

 ing order, i.e. from lighter to heavier than vice versa. G. E. Muller and 

 Schumann have pointed out the great influence of precurrent effect upon the 

 judgment of a succeeding one. A Aveight, 826 grms., when compared ten times, 

 with all precautions for rendering judgment unbiassed, against a "standard" 

 weight 626 grms., was once pronounced the lighter, twice pronounced equal, 



1 Sunkel, " Inaug. Diss.," Marburg. 1890. 



