Moment of inertia: psychophysical study of an overlooked sensation.

The distribution of mass in an object held in the hand, as described by its moment of inertia, is a fundamental and potent but largely unrecognized contributor to the object's "feel." A limited set of experiments has produced Weber fractions for human differential sensitivity to this property in the approximate range of 1/5 to 1/3, which is about ten times the Weber fraction reported for lifted weights.