Smits-Engelsman B C M, Rameckers E A A, Duysens J
Motor Control Lab, Department of Kinesiology, K.U. Leuven, Leuven, Belgium.
Exp Brain Res. 2007 Mar;177(4):431-9. doi: 10.1007/s00221-006-0698-x. Epub 2006 Sep 22.
Fitts' Law is commonly found to apply to motor tasks involving precise aiming movements. Children with cerebral palsy (CP) have severe difficulties in such tasks and it is unknown whether they obey Fitts' Law despite their motor difficulties. If Fitts' Law still does apply to these children, this would indicate that this law is extremely robust and that even performance of children with damaged central nervous systems can adhere to it. The integrity of motor control processes in spastic CP is usually tested in complex motor tasks, making it difficult to determine whether poor performance is due to a motor output deficit or to problems related to cognitive processes since both affect movement precision. In the present study a simple task was designed to evaluate Fitts' Law. Tapping movements were evaluated in 22 children with congenital spastic hemiplegia (CSH) and 22 typically developing children. Targets (2.5 and 5 cm in width) were placed at distances of 10 and 20 cm from each other in order to provide Indices of Difficulty (ID) of 2-4 bits. Using this Fitts' aiming task, prolonged reaction and movement time (MT) were found in the affected hand under all conditions in children with CSH as compared to controls. Like in the control group, MT in children with CSH was related to ID. The intercept 'a', corresponding to the time required to realize a tapping movement, was higher in the affected hand of the children in the CSH group. Although, the slope b (which reflects the sensitivity of the motor system to a change in difficulty of the task) and the reciprocal of slope (that represents the cognitive information processing capacity, expressed in bits/s) were similar in both groups. In conclusion, children with CSH obey Fitts' Law despite very obvious limitations in fine motor control.
菲茨定律通常适用于涉及精确瞄准动作的运动任务。脑瘫（CP）儿童在这类任务中存在严重困难，尽管他们存在运动障碍，但尚不清楚他们是否遵循菲茨定律。如果菲茨定律仍然适用于这些儿童，这将表明该定律极其稳健，即使是中枢神经系统受损的儿童的表现也能遵循它。痉挛型脑瘫运动控制过程的完整性通常在复杂的运动任务中进行测试，由于运动输出缺陷和与认知过程相关的问题都会影响运动精度，因此很难确定表现不佳是由于运动输出缺陷还是与认知过程相关的问题。在本研究中，设计了一个简单的任务来评估菲茨定律。对22名先天性痉挛性偏瘫（CSH）儿童和22名发育正常的儿童的敲击动作进行了评估。目标（宽度为2.5厘米和5厘米）相互之间的距离为10厘米和20厘米，以提供2 - 4比特的难度指数（ID）。使用这个菲茨瞄准任务，与对照组相比，在所有条件下，CSH儿童患侧手的反应时间和运动时间（MT）都延长了。与对照组一样，CSH儿童的MT与ID有关。CSH组儿童患侧手的截距“a”（对应于实现敲击动作所需的时间）更高。尽管两组的斜率b（反映运动系统对任务难度变化的敏感性）和斜率的倒数（代表认知信息处理能力，以比特/秒表示）相似。总之，尽管CSH儿童在精细运动控制方面存在非常明显的局限性，但他们仍遵循菲茨定律。
