The optimal viewing position (OVP) effect indicates that words are identified most quickly when the eyes fixate near the word centre in alphabetic languages. In two studies, we tested OVP in typically developing readers and children with developmental dyslexia (DD), developmental coordination disorder (DCD) and with both disorders (DD + DCD), using a variable-viewing-position technique. Study 1 showed that typically developing readers had developed highly automatized procedures of left-to-right attentional scanning resulting in an inverted J-shape VP curve comparable to what is observed in adult readers and that dyslexics showed non-prototypical one. In Study 2, we observed more typical procedures of left-to-right attentional scanning in children with DCD, isolated or comorbid, compared to DD. Moreover, given the absence of significant group differences between children with DD + DCD and children with isolated DD or DCD, our results reinforce the idea that the comorbid condition does not add to the severity of OVP anomalies. We then concluded that OVP atypicalities are specific to children with DD. Finally, we discussed the usefulness of the OVP effect as a clinical tool to identify possible OVP atypicalities that could be specific of some neurodevelopmental disorders (i.e., DD, DCD or DCD + DD).

中文翻译：

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“相同，相同但不同”：发育性阅读障碍、发育性协调障碍和共病障碍的最佳观看位置效应

最佳观看位置 (OVP) 效果表明，当眼睛注视字母语言中的单词中心附近时，识别单词的速度最快。在两项研究中，我们使用可变观察位置技术在典型发育中的阅读器和患有发育性阅读障碍 (DD)、发育性协调障碍 (DCD) 和两种疾病 (DD + DCD) 的儿童中测试了 OVP。研究 1 表明，典型的发展中的读者已经开发出高度自动化的从左到右注意力扫描的程序，导致倒J-shape VP 曲线与在成人读者中观察到的相当，并且阅读障碍者表现出非典型曲线。在研究 2 中，与 DD 相比，我们在患有孤立性或合并症的 DCD 儿童中观察到了更典型的从左到右注意力扫描的程序。此外，鉴于 DD + DCD 儿童与孤立性 DD 或 DCD 儿童之间没有显着的组别差异，我们的结果强化了这样的观点，即合并症不会增加 OVP 异常的严重程度。然后我们得出结论，OVP 非典型性是 DD 儿童特有的。最后，我们讨论了 OVP 效应作为临床工具的有用性，以确定可能特定于某些神经发育障碍（即，DD、DCD 或 DCD + DD）的可能的 OVP 非典型性。