Calibration is both functional and anatomical.

Bingham and Pagano (1998) described calibration as a mapping from embodied perceptual units to an embodied action unit and suggested that it is an inherent component of perception/action that yields accurate targeted actions. We tested two predictions of this "Mapping Theory." First, calibration should transfer between limbs, because it involves a mapping from perceptual units to an action unit, and thus is functionally specific to the action (Pan, Coats, and Bingham, 2014). We used distorted haptic feedback to calibrate feedforward right hand reaches and tested right and left hand reaches after calibration. The calibration transferred. Second, the Mapping Theory predicts that limb specific calibration should be possible because the units are embodied and anatomy contributes to their scaling. Limbs must be calibrated to one another given potential anatomical differences among limbs. We used distorted haptic feedback to calibrate feedforward reaches with right and left arms simultaneously in opposite directions relative to a visually specified target. Reaches tested after calibration revealed reliable limb specific calibration. Both predictions were confirmed. This resolves a prevailing controversy as to whether calibration is functional (Bruggeman & Warren, 2010; Rieser, Pick, Ashmead, & Garing, 1995) or anatomical (Durgin et al., 2003; Durgin & Pelah, 1999). Necessarily, it is both.