Department of Psychology, Royal Holloway, University of London, UK.
Dev Sci. 2012 May;15(3):299-306. doi: 10.1111/j.1467-7687.2011.01123.x. Epub 2012 Mar 1.
Almost all locomotor animals are sensitive to optical expansion (visual looming) and for most animals this sensitivity is evident very early in their development. In humans there is evidence that responses to looming stimuli begin in the first 6 weeks of life, but here we demonstrate that as children become independent their perceptual acuity needs to be 50 to 100 times better than has been demonstrated in infants in order to be skilful at collision avoidance at a roadside. We have recently established that sensitivity to the detection of visual looming in 6- to 11-year-old children is significantly below that of adults (Wann, Poulter & Purcell, 2011). Here, using comparable methods, we explore looming detection sensitivity in children with Developmental Co-ordination Disorder (DCD), who show broad patterns of impairment in visuo-motor control. We presented visual simulations of approaching vehicles, scaled to represent different approach rates, to children with DCD aged between 6 and 11 years (n = 11) and typically developing age and gender matched controls (n = 11). Looming detection thresholds were measured under foveal and perifoveal viewing conditions, for isotropic expansion and isotropic expansion with simulated viewpoint motion. Our results show that there are situations in which children with DCD may fail to detect vehicles approaching at speeds in excess of 22 km/h, suggesting a developmental immaturity in looming sensitivity. This provides one of the first clear demonstrations of low-level motion processing deficits in children with DCD. The decrement observed may give rise to potential errors in the road crossing behaviour of these children, whereby approaching vehicles could be perceived as stationary. These findings further contribute towards understanding the adverse statistic that children under 9 years of age are four times more likely than adults to be involved in a road accident as a pedestrian.
几乎所有的运动动物对光的扩展（视觉逼近）都很敏感，对于大多数动物来说，这种敏感性在它们的早期发展中就很明显。有证据表明，人类对逼近刺激的反应在生命的头 6 周就开始了，但在这里我们证明，随着孩子变得独立，他们的感知能力需要比婴儿在路边躲避碰撞时表现出的能力好 50 到 100 倍。我们最近的研究表明，6 至 11 岁儿童对视觉逼近的检测敏感性明显低于成年人（Wann、Poulter 和 Purcell，2011）。在这里，我们使用类似的方法，探索了患有发育协调障碍（DCD）的儿童在视觉逼近检测敏感性方面的情况，他们在视动控制方面表现出广泛的损伤模式。我们向 6 至 11 岁的 DCD 儿童和年龄和性别匹配的正常发育对照组儿童展示了接近车辆的视觉模拟，这些模拟按照不同的接近速度进行了缩放，以代表不同的接近速度。我们在中央凹和周边视野条件下，对各向同性扩展和各向同性扩展模拟视角运动的情况，测量了逼近检测阈值。我们的结果表明，在某些情况下，DCD 儿童可能无法检测到以超过 22 公里/小时的速度接近的车辆，这表明他们在逼近敏感性方面存在发育不成熟。这首次清楚地证明了 DCD 儿童在低水平运动处理方面存在缺陷。观察到的这种缺陷可能会导致这些儿童在过马路时产生潜在的错误，即他们可能会将接近的车辆视为静止的。这些发现进一步有助于理解一个不利的统计数据，即 9 岁以下的儿童作为行人发生道路事故的可能性是成年人的四倍。
