Karlsson Emma M, Hugdahl Kenneth, Hirnstein Marco, Carey David P
Institute of Cognitive Neuroscience, School of Human and Behavioural Sciences, Bangor University, Bangor, United Kingdom.
Department of Experimental Psychology, Ghent University, Ghent, Belgium.
Cereb Cortex Commun. 2023 Jun 1;4(2):tgad009. doi: 10.1093/texcom/tgad009. eCollection 2023.
About 95% of right-handers and 70% of left-handers have a left-hemispheric specialization for language. Dichotic listening is often used as an indirect measure of this language asymmetry. However, while it reliably produces a right-ear advantage (REA), corresponding to the left-hemispheric specialization of language, it paradoxically often fails to obtain statistical evidence of mean differences between left- and right-handers. We hypothesized that non-normality of the underlying distributions might be in part responsible for the similarities in means. Here, we compare the mean ear advantage scores, and also contrast the distributions at multiple quantiles, in two large independent samples (Ns = 1,358 and 1,042) of right-handers and left-handers. Right-handers had an increased mean REA, and a larger proportion had an REA than in the left-handers. We also found that more left-handers are represented in the left-eared end of the distribution. These data suggest that subtle shifts in the distributions of DL scores for right- and left-handers may be at least partially responsible for the unreliability of significantly reduced mean REA in left-handers.
约95%的右利手者和70%的左利手者在语言方面表现出左半球优势。双耳分听常常被用作这种语言不对称性的一种间接测量方法。然而，尽管它能可靠地产生右耳优势（REA），这与语言的左半球优势相对应，但矛盾的是，它常常无法获得左利手者和右利手者之间平均差异的统计证据。我们推测，潜在分布的非正态性可能在一定程度上导致了均值的相似性。在此，我们比较了右利手者和左利手者的两个大型独立样本（样本量分别为1358人和1042人）的平均耳优势得分，并在多个分位数上对比了分布情况。右利手者的平均右耳优势增加，且具有右耳优势的比例高于左利手者。我们还发现，在分布的左耳端，左利手者的比例更高。这些数据表明，右利手者和左利手者在双耳分听得分分布上的细微变化，可能至少部分导致了左利手者平均右耳优势显著降低的不可靠性。
