Child Rehabilitation Centre, Department of Physical Medicine and Rehabilitation, Ghent University Hospital, 9000 Ghent, Belgium.
Department of Physical Medicine and Rehabilitation, Ghent University Hospital, 9000 Ghent, Belgium.
J Exp Child Psychol. 2021 Mar;203:105016. doi: 10.1016/j.jecp.2020.105016. Epub 2020 Nov 24.
Whereas we experience our body as a coherent volumetric object, the brain appears to maintain highly fragmented representations of individual body parts. Little is known about how body representations of hand size and shape are built and evolve during infancy and young adulthood. This study aimed to investigate the effect of hand side, handedness, and age on the development of central hand size representation. The observational study with comparison groups was conducted with 90 typically developing Belgian school children and young adults (48 male and 42 female; age range = 5.0-23.0 years; 49 left-handed and 41 right-handed). Participants estimated their hand size and shape using two different tasks. In the localization task, participants were verbally cued to judge the locations of 10 anatomical landmarks of an occluded hand. An implicit hand size map was constructed and compared with actual hand dimensions. In the template selection task, the explicit hand shape was measured with a depictive method. Hand shape indexes were calculated and compared for the actual, implicit, and explicit conditions. Participants were divided into four age groups (5-8 years, 9-10 years, 11-16 years, and 17-23 years). Implicit hand maps featured underestimation of finger length and overestimation of hand width, which is already present in the youngest children. Linear mixed modeling revealed no influence of hand side on finger length underestimation; nonetheless, a significant main effect of age (p = .001) was exposed. Sinistrals aged 11 to 16 years showed significantly less underestimation (p = .03) than dextrals of the same age. As for the hand shape, the implicit condition differed significantly with the actual and explicit conditions (p < .001). Again, the implicit shape index was subjected to handedness and age effects, with significant differences being found between sinistrals and dextrals in the age groups of 9 and 10 years (p = .029) and 11 to 16 years (p < .001). In conclusion, the implicit metric component of the hand representation in children and young adults is misperceived, featuring shortened fingers and broadened hands since a very young age. Crucially, the finger length underestimation increases with age and shows a different developmental trajectory for sinistrals and dextrals. In contrast, the explicit hand shape is approximately veridical and seems immune from age and handedness effects. This study confirms the dual character of somatoperception and establishes a point of reference for children and young adults.
虽然我们将身体体验为一个连贯的体积物体，但大脑似乎保持着个体身体部位高度碎片化的表示。关于手的大小和形状的身体表示如何在婴儿期和成年早期建立和发展，人们知之甚少。本研究旨在调查手的侧别、利手性和年龄对手的大小表示的发展的影响。这项具有对照组的观察性研究是在 90 名比利时正常发育的学龄儿童和年轻人（48 名男性和 42 名女性；年龄范围为 5.0-23.0 岁；49 名左利手和 41 名右利手）中进行的。参与者使用两种不同的任务来估计他们的手的大小和形状。在定位任务中，参与者通过口头提示来判断一个被遮挡的手的 10 个解剖学标记的位置。构建了一个隐含的手大小图，并与实际的手尺寸进行了比较。在模板选择任务中，通过描述性方法测量了手的明确形状。计算并比较了实际、隐含和明确条件下的手形指数。参与者被分为四个年龄组（5-8 岁、9-10 岁、11-16 岁和 17-23 岁）。隐含的手图特征是手指长度被低估，手掌宽度被高估，这种情况在最小的孩子中就已经存在。线性混合模型显示手的侧别对手指长度的低估没有影响；尽管如此，年龄的主要影响（p=.001）还是暴露了出来。11 至 16 岁的左利手者的低估程度明显低于同龄的右利手者（p=.03）。至于手的形状，隐含条件与实际和明确条件有显著差异（p<.001）。同样，隐含的形状指数受到利手性和年龄的影响，在 9 岁和 10 岁以及 11 岁至 16 岁的年龄组中，左利手者和右利手者之间存在显著差异（p=.029）和 11 至 16 岁（p<.001）。总之，儿童和年轻人对手的代表的隐含度量成分被误解了，从很小的时候起，手指就变短了，手掌变宽了。至关重要的是，手指长度的低估随着年龄的增长而增加，并且左利手者和右利手者的发展轨迹不同。相比之下，明确的手形大约是正确的，并且似乎不受年龄和利手性的影响。本研究证实了躯体知觉的双重特征，并为儿童和年轻人建立了一个参考点。
