Bingham Geoffrey P, Hughes Kirstie, Mon-Williams Mark
Department of Psychology, Indiana University, Bloomington, IN 47405, USA.
Exp Brain Res. 2008 Jan;184(3):283-93. doi: 10.1007/s00221-007-1107-9. Epub 2007 Aug 29.
What determines coordination patterns when both hands reach to grasp separate objects at the same time? It is known that synchronous timing is preferred as the most stable mode of bimanual coordination. Nonetheless, normal unimanual prehension behaviour predicts asynchrony when the two hands reach towards unequal targets, with synchrony restricted to targets equal in size and distance. Additionally, sufficiently separated targets require sequential looking. Does synchrony occur in all cases because it is preferred in bimanual coordination or does asynchrony occur because of unimanual task constraints and the need for sequential looking? We investigated coordinative timing when participants (n = 8) moved their right (preferred) hand to the same object at a fixed distance but the left hand to objects of different width (3, 5, and 7 cm) and grip surface size (1, 2, and 3 cm) placed at different distances (20, 30, and 40 cm) over 270 randomised trials. The hand movements consisted of two components: (1) an initial component (IC) during which the hand reached towards the target while forming an appropriate grip aperture, stopping at (but not touching) the object; (2) a completion component (CC) during which the finger and thumb closed on the target. The two limbs started the IC together but did not interact until the deceleration phase when evidence of synchronisation began to appear. Nonetheless, asynchronous timing was present at the end of the IC and preserved through the CC even with equidistant targets. Thus, there was synchrony but requirements for visual information ultimately yielded asynchronous coordinative timing.
当双手同时伸手去抓握不同的物体时,是什么决定了协调模式?众所周知,同步计时作为双手协调最稳定的模式更受青睐。然而,正常的单手抓握行为预测,当双手伸向不等距目标时会出现异步,同步则仅限于大小和距离相等的目标。此外,相距足够远的目标需要依次注视。同步在所有情况下都会出现是因为它在双手协调中更受青睐,还是异步的出现是由于单手任务限制和依次注视的需要?我们研究了参与者(n = 8)在270次随机试验中,将右手(优势手)移向固定距离处的同一物体,而左手移向放置在不同距离(20、30和40厘米)处、具有不同宽度(3、5和7厘米)和握持表面尺寸(1、2和3厘米)的物体时的协调计时。手部动作由两个部分组成:(1)初始部分(IC),在此期间手伸向目标,同时形成适当的抓握孔径,在物体处(但不接触)停下;(2)完成部分(CC),在此期间手指和拇指闭合抓住目标。两条肢体同时开始初始部分,但直到减速阶段同步迹象开始出现时才相互作用。尽管如此,即使目标等距,在初始部分结束时仍存在异步计时,并在完成部分保持。因此,存在同步,但对视觉信息的需求最终产生了异步协调计时。