Abstract：
This study examined the co-development of infant reaching and postural control across the transition to arms-free sitting at home. We observed infants with typical likelihood (TL; n = 24) and elevated likelihood (EL; n = 20) for autism at four biweekly sessions spanning the transition to arms-free sitting (infant age = 4.5-8 months at first session). At each session, infants sat on a pressure-sensitive mat with external support or independently, wore magneto-inertial sensors on both wrists, and reached for toys presented at midline. Analyses focused on characterizing and comparing control of sitting during reaching actions and standard kinematic metrics of reaching during Supported versus Independent Sitting. Although EL infants achieved arms-free sitting later than TL peers, there were no group differences on any measures. Across sessions, infants\' control of the sitting posture during concurrent reaching movements improved in both contexts, though they were less stable as they reached when sitting independently compared to when sitting with support. A similar effect was apparent in the kinematics of reaches, with overall improvement over time, but evidence of poorer control in Independent relative to Supported Sitting. Taken together, these findings underscore the mutually influential and dynamic relations between emerging skills and well-established behaviors.
摘要：
这项研究研究了在向无手臂坐在家中过渡的过程中，婴儿伸手和姿势控制的共同发育。我们观察到，在四个两周的疗程中，患有自闭症的婴儿具有典型的可能性（TL;n=24）和较高的可能性（EL;n=20），整个过渡到无武器坐着（婴儿年龄=4.5-8个月在第一次疗程）。在每届会议上,婴儿坐在有外部支撑或独立的压敏垫上，两个手腕上都戴着磁惯性传感器，伸手去拿中线赠送的玩具。分析的重点是表征和比较到达动作期间的坐姿控制以及在支持坐姿和独立坐姿期间的标准运动学指标。尽管EL婴儿比TL同龄人晚实现无手臂坐姿，在任何测量方面均无组间差异.在整个会议上，在两种情况下，婴儿在同时到达运动期间对坐姿的控制都得到了改善，尽管它们在独立坐着时比在支撑下坐着时更不稳定。在河段的运动学中也有类似的效果，随着时间的推移，总体上有所改善，但有证据表明，相对于支持坐姿，独立控制较差。一起来看,这些发现强调了新兴技能和既定行为之间的相互影响和动态关系。
