Matrix Analyses of Interaction among Fingers

When a person produces a force with a fingertip, other fingers of the hand also show an increase in their force. This phenomenon has been termed enslaving (Li et al. 1998a; Zatsiorsky et al. 2000). When several fingers are activated simultaneously, the relations among fingers can be described with an inter-finger matrix (IMF). We suggest using the IMFs to quantify individual differences among humans. An IFM for a hand contains 16 numbers. Hence, in general, individual differences in finger interaction, as reflected in IFMs, may require 16 variables to be fully described. We hypothesize, however, that a significantly smaller number of variables may be sufficient to describe differences among individuals without special skills. Hence, a major goal of this study has been to discover such variables and relate them to indices of finger interaction introduced in earlier studies.