Does Attention Modify Contributions to Heaviness Perception?

The current study investigated the effect of attention on heaviness perception and its physiological and kinematic contributions. Participants lifted objects that varied in mass and volume while their muscle activity and movement were recorded. Participants were instructed to pay attention to their arm (internal) or the object (external). While heaviness perception did not change as a function of attention, whether muscle activity and movement combined for perception differed across attention conditions. Specifically, muscle activity and movement combined to significantly predict heaviness perception in the external condition, but not the internal condition. Additionally, movement was more salient for perception in both conditions compared to previous research investigating the contribution of muscle activity and movement to heaviness perception. It is suggested that these results support the constrained action hypothesis, which suggests that adopting an external focus of attention benefits motor task performance and learning, and should be further explored in the context of a theory of haptic perception that suggests that the medium for haptic perception is the multifractal tensegrity structure of the body.