Manual Asymmetry During Object Release

Occupational therapists traditionally have had a keen interest in the issue of hand p re f e rence (Clark & Allen, 1985; Clerke & Clerke, 2001; Knickerboker, 1980). Children who are delayed in developing a consistent pre f e rence commonly a re recommended for occupational therapy because of its presumed effects on fin e motor skills, bilateral coordination, and midline crossing (Fi s h e r, Mu r r a y, & Bu n d y, 1991; St i l well, 1987). In addition, patients with hemiplegia, hand injury, or upper-extremity disease often re q u i re “dominance retraining.” Although a common assumption is that performance of the nondominant hand is signific a n t l y diminished compared with the dominant hand, previous studies, particularly those i n volving kinematic and kinetic analysis, have yielded differing results. A major concern of occupational therapy also has been the identification of task parameters and conditions that affect performance through the use of task analysis. T h e re f o re , it is important to understand what task conditions influence asymmetrical hand skill for both assessment and treatment purposes. Yet, little is known about how p e rformance differences between the dominant and nondominant hands are affected by task conditions, and few studies within the occupational therapy litera t u re have addressed this issue (Larkin, 1989; Walsh, Belding, Ta y l o r, & Nu n l e y, 1993).