Beyond group averages: why motor control studies must address population and individual heterogeneity

Abstract

TO THE EDITOR: Kim et al. (1) make an important conceptual contribution by distinguishing force variability from force smoothness during isometric contractions, demonstrating that these metrics respond differently to visual gain manipulation. However, the study suffers from two fundamental problems that undermine its scientific validity: 1) a demographically opaque convenience sample of 14 participants presented as revealing universal principles of human motor control, and 2) visible individual heterogeneity in the data that is completely ignored in favor of group averages. These issues exemplify what I term the “dual diversity crisis” in neuroscience research—the simultaneous neglect of both population diversity and brain diversity.