Department of Biological and Medical Psychology, University of Bergen Bergen, Norway.
Department of Biological and Medical Psychology, University of Bergen Bergen, Norway ; Division of Psychiatry, Haukeland University Hospital Bergen, Norway ; Department of Radiology, Haukeland University Hospital Oslo, Norway.
Front Psychol. 2014 Jan 2;4:997. doi: 10.3389/fpsyg.2013.00997. eCollection 2014.
All major mental functions including language, spatial and emotional processing are lateralized but how strongly and to which hemisphere is subject to inter- and intraindividual variation. Relatively little, however, is known about how the degree and direction of lateralization affect how well the functions are carried out, i.e., how lateralization and task performance are related. The present study therefore examined the relationship between lateralization and performance in a dichotic listening task for which we had data available from 1839 participants. In this task, consonant-vowel syllables are presented simultaneously to the left and right ear, such that each ear receives a different syllable. When asked which of the two they heard best, participants typically report more syllables from the right ear, which is a marker of left-hemispheric speech dominance. We calculated the degree of lateralization (based on the difference between correct left and right ear reports) and correlated it with overall response accuracy (left plus right ear reports). In addition, we used reference models to control for statistical interdependency between left and right ear reports. The results revealed a u-shaped relationship between degree of lateralization and overall accuracy: the stronger the left or right ear advantage, the better the overall accuracy. This u-shaped asymmetry-performance relationship consistently emerged in males, females, right-/non-right-handers, and different age groups. Taken together, the present study demonstrates that performance on lateralized language functions depends on how strongly these functions are lateralized. The present study further stresses the importance of controlling for statistical interdependency when examining asymmetry-performance relationships in general.
所有主要的心理功能，包括语言、空间和情感处理，都是偏侧化的，但偏侧化的程度和偏向哪个半球则存在个体间和个体内的差异。然而，人们对偏侧化的程度和方向如何影响功能的执行程度，即偏侧化和任务表现之间的关系，知之甚少。因此，本研究考察了在双耳分听任务中的偏侧化和表现之间的关系，我们有 1839 名参与者的数据可用于该任务。在这个任务中，辅音-元音音节同时呈现给左耳和右耳，这样每个耳朵接收一个不同的音节。当被问及他们听到的最好的是哪一个音节时，参与者通常会报告更多来自右耳的音节，这是左半球言语优势的标志。我们计算了偏侧化的程度（基于正确的左耳和右耳报告之间的差异），并将其与整体反应准确性（左耳和右耳报告的总和）相关联。此外，我们使用参考模型来控制左右耳报告之间的统计相关性。结果表明，偏侧化程度与整体准确性之间存在 U 形关系：左或右耳优势越强，整体准确性越高。这种 U 形的不对称-表现关系在男性、女性、右撇子和非右撇子以及不同年龄组中一致出现。总之，本研究表明，偏侧化语言功能的表现取决于这些功能的偏侧化程度。本研究进一步强调了在一般检查不对称-表现关系时，控制统计相关性的重要性。
