Distance-dependent modulation of sensory attenuation during motor imagery and overt action.

Motor imagery is thought to engage forward models that predict the sensory consequences of action, but it remains unclear whether these predictions exhibit the same spatial tuning as those during overt movement. The present study examined how sensory attenuation varies as a function of spatial separation during executed and imagined actions. Twelve participants performed a force-matching task under baseline, pressing, and imagery conditions while the distance between the acting and receiving fingers was manipulated (0, 12.5, 25 cm). Sensory attenuation was quantified as force reproduction error relative to baseline. Results revealed a significant Distance × Condition interaction. Polynomial trend analyses indicated that force reproduction error increased linearly with distance in all conditions, but at different rates: attenuation during overt pressing declined more steeply with distance and was largely absent at 25 cm, whereas attenuation during motor imagery decreased more gradually and was maintained across larger separations. These findings suggest that motor imagery and overt action engage predictive mechanisms with somewhat different spatial characteristics, consistent with the view that forward model precision is influenced by the availability of movement-related sensory feedback.