• When lifting objects that are lighter or heaver than we expect them to be, individuals typically misapply forces in a way that reflects their prior expectations of heaviness.
• Because we lift in this predictive way, large and small cubes elicit these characteristic errors even when they are adjusted to have equal mass. Lifters will apply too much force to a large cube and substantially less force to a small cube – errors that are rapidly corrected with repeated lifts (Flanagan & Beltzner, 2000).
• When watching others lift objects, an observer’s motor system automatically reacts in a way that reflects the object’s weight (Alaerts et al., 2010). It is, however, unclear how the motor system reacts to observing lifting errors.
• To examine how observing an action improves motor learning in the context of fingertip force scaling, participants watched a video of an object lifting task before lifting equally-weighted large and small cubes themselves.
• To determine what style of kinematic information is more valuable to observe, participants watched either error filled, first-time lifts or error free, expert lifts before lifting these equally-weighted small and large cubes themselves.