Isolated and sequenced oral motor posture production under different input modalities by left-hemisphere damaged...

The purpose of this investigation was to use a well-refined system of oral movement notation to examine whether the quality of performances for production of elemental oral motor postures as isolated targets was similar to performances of the same postures produced as members of a sequence by left-hemisphere damaged (LHD) and normal adults. The effect of input modality was also examined using three conditions--imitation, photograph and command. Result suggested that "additional movements" and "errors of spatial alignment" prominently characterized both isolated and sequenced postural production errors made by both LHD and normal adults. The frequency of occurrence of these behaviours, however, was dramatically higher among the LHD subjects. Moreover, the quality of productions of oral postures deteriorated in sequences of increasing length among the LHD subjects but not among normal adults. No differential effect for mode of input was found for the LHD subjects but was for the normal adults. Results suggested that the inferior performances of LHD subjects on isolated gesture production are due to exaggerated augmentations and spatial targeting deficits. Sequence production was affected negatively by the same behaviours as well as a disability for "phasing" subcomponents of discrete movements as reflected by a significant increase in "complex" errors on the individual gestures comprising the sequence.