To understand the grasping abnormalities in Parkinson's or stroke patients, normal grasping must be examined, and whether that normality is determined by biological factors or experiential influence must also be considered. The purpose of this thesis is to determine what normal variations of precision grasping exist in healthy, normal adults, children and elderly people. Using Eshkol-Wachmann Movement Notation, five types of contact strategies were interpolated, based on the digit that contacts the object first, and whether that digit dragged or stabilized the object for grasping. Each contact strategy was associated with an ideal graphical representation of the thumb and index finger velocities. There were seven variations of purchase patterns, based on the digits used to contact the objects, and four variations of postures of the non-grasping digits on top of the five contact strategies. Object size affected purchase pattern preference: smaller objects elicited the pincer grasp more than the larger objects. The purchase pattern distribution of variation is similar in adults and children, although children exhibit an extra purchase pattern, and older adults exhibit less variation purchase patterns. The findings from this thesis suggest that central factors, such as gender and handedness, as well as external factors, such as size of the object, determine individual preference of grasping. The loss of variation with age can be attributed to the developing corticospinal tract in children as well as the deterioration of normal hand function in the elderly. / ix, 116 leaves : ill. ; 29 cm.