Flattening of distinctions in a Parkinsonian signer

The analysis of motor deficits in Parkinsonian signing provides an important new vehicle for understanding the ongoing interplay between linguistic intelligibility and processes that ease articulation. Field-by-field video analysis was performed on two elicited narratives from a 72-year-old, congenitally deaf, Parkinsonian signer. This analysis revealed that although the overall topography of the signing space was maintained, preserving movement contours and trajectories, the actual sign articulations were miniaturized and laxed. At times the non-dominant left hand shadowed the handshape of the dominant right, or two consecutive signs were blended into a single portmanteau form. Moreover, within utterances there was an abnormally uniform rhythmic pattern. While the Parkinsonian signer reduced amplitude, crispness, and rhythmic variation, he stopped short of obliterating linguistically relevant distinctions, which implies that an intact linguistic system was clamped by a more general motor deficit.