Leg Perception of Object Heaviness

ABSTRACT Perceived heaviness is a function of both the muscle activity used to wield an object and the resulting movement. Wielding reveals invariant properties of the effector-object system, such as rotational inertia. Recent research has proposed a psychophysiological mechanism for perceiving the heaviness of a handheld object through dynamic touch that captures how arm muscle activity and angular movement combined reveal this invariance (Waddell, Fine, Likens, Amazeen & Amazeen, 2016). The current study extends this hypothesis by investigating the dynamics of heaviness perception with the leg. Participants lifted objects of varying mass with knee extension lifts while reporting perceived heaviness. During each lift, the electromyogram (EMG) was recorded from the quadriceps, and peak angular acceleration was recorded about the knee. The resulting psychophysiological function revealed the hypothesized ratio of muscle activity to movement, similar to that found in Waddell et al. (2016). This suggests that the dynamics for heaviness perception in the leg is similar to that shown in the arm in previous work.