School of Pedagogical and Educational Science, Radboud University Nijmegen , The Netherlands.
PeerJ. 2015 Mar 26;3:e837. doi: 10.7717/peerj.837. eCollection 2015.
Several competing aetiologies of developmental dyslexia suggest that the problems with acquiring literacy skills are causally entailed by low-level auditory and/or speech perception processes. The purpose of this study is to evaluate the diverging claims about the specific deficient peceptual processes under conditions of strong inference. Theoretically relevant acoustic features were extracted from a set of artificial speech stimuli that lie on a /bAk/-/dAk/ continuum. The features were tested on their ability to enable a simple classifier (Quadratic Discriminant Analysis) to reproduce the observed classification performance of average and dyslexic readers in a speech perception experiment. The 'classical' features examined were based on component process accounts of developmental dyslexia such as the supposed deficit in Envelope Rise Time detection and the deficit in the detection of rapid changes in the distribution of energy in the frequency spectrum (formant transitions). Studies examining these temporal processing deficit hypotheses do not employ measures that quantify the temporal dynamics of stimuli. It is shown that measures based on quantification of the dynamics of complex, interaction-dominant systems (Recurrence Quantification Analysis and the multifractal spectrum) enable QDA to classify the stimuli almost identically as observed in dyslexic and average reading participants. It seems unlikely that participants used any of the features that are traditionally associated with accounts of (impaired) speech perception. The nature of the variables quantifying the temporal dynamics of the speech stimuli imply that the classification of speech stimuli cannot be regarded as a linear aggregate of component processes that each parse the acoustic signal independent of one another, as is assumed by the 'classical' aetiologies of developmental dyslexia. It is suggested that the results imply that the differences in speech perception performance between average and dyslexic readers represent a scaled continuum rather than being caused by a specific deficient component.
几种相互竞争的发展性阅读障碍病因假说表明，获得读写技能的问题是由低级听觉和/或言语感知过程的因果关系引起的。本研究的目的是在强推理条件下评估关于特定感知过程缺陷的不同说法。从一组位于/bAk/-/dAk/连续体上的人工语音刺激中提取了与理论相关的声学特征。这些特征的测试能力是，它们是否能使一个简单的分类器（二次判别分析）复制在语音感知实验中观察到的平均阅读者和阅读障碍者的观察到的分类性能。所检查的“经典”特征基于发展性阅读障碍的成分过程理论，例如在包络上升时间检测中的假定缺陷以及在频谱中能量分布的快速变化（共振峰转换）检测中的缺陷。研究这些时间处理缺陷假说的研究不采用量化刺激时间动态的测量方法。结果表明，基于量化复杂、相互作用主导系统动态的测量方法（递归量化分析和多重分形谱）使 QDA 能够几乎与阅读障碍者和普通阅读者的观察结果一样对刺激进行分类。参与者不太可能使用与（受损）言语感知理论相关的任何特征。量化语音刺激时间动态的变量的性质意味着，不能将语音刺激的分类视为线性聚合的组成过程，正如发展性阅读障碍的“经典”病因学所假设的那样，每个过程都独立地解析声学信号。因此，结果表明，平均阅读者和阅读障碍者之间的语音感知表现差异代表一个缩放连续体，而不是由特定的缺陷成分引起的。
