Department of Psychology, University of Oslo, Oslo, Norway.
Department of Life and Environmental Sciences, Polytechnic University of Marche, Ancona, Italy.
Neuropsychologia. 2023 Sep 9;188:108627. doi: 10.1016/j.neuropsychologia.2023.108627. Epub 2023 Jun 20.
The surgical section of the corpus callosum (callosotomy) has been frequently demonstrated to result in a left-ear extinction in dichotic listening. That is, callosotomy patients report the left-ear stimulus below chance level, resulting in substantially enhanced right-ear advantage (REA) compared with controls. A small number of previous studies also suggest that callosotomy patients can overcome left-ear extinction when the instruction encourages to attend selectively to the left-ear stimulus. In the present case study, we re-examine the role of selective attention in dichotic listening in two patients with complete callosotomy and 40 age- and sex-matched controls. We used the standardised Bergen dichotic-listening paradigm which uses stop-consonant-vowel syllables as stimulus material and includes both a free-report and selective-attention condition. As was predicted, both patients showed a clear left-ear extinction. However, contrasting the earlier reports, we did not find any evidence for a relief from this extinction by selectively attending to the left-ear stimulus. We conclude that previous demonstrations of an attention-improved left-ear recall in callosotomy patients may be attributed to the use of suboptimal dichotic paradigms or residual callosal connectivity, rather than representing a genuine effect of attention.
胼胝体的手术部分（胼胝体切开术）经常被证明会导致双耳分听中的左耳消失。也就是说，胼胝体切开术患者报告左耳刺激的反应低于机会水平，与对照组相比，右侧耳优势（REA）显著增强。少数先前的研究还表明，当指令鼓励选择性地注意左耳刺激时，胼胝体切开术患者可以克服左耳消失。在本案例研究中，我们使用标准的卑尔根双耳分听范式重新检查了两名完全胼胝体切开术患者和 40 名年龄和性别匹配的对照者在双耳分听中的选择性注意作用。该范式使用停止辅音-元音音节作为刺激材料，包括自由报告和选择性注意条件。正如预测的那样，两名患者均表现出明显的左耳消失。然而，与早期的报告相反，我们没有发现任何证据表明通过选择性地注意左耳刺激可以减轻这种消失。我们的结论是，先前在胼胝体切开术患者中观察到的注意力改善的左耳回忆可能归因于使用了次优的双耳分听范式或残留的胼胝体连接，而不是真正的注意力效应。
