Dichotic-listening performance after complete callosotomy: No relief from left-ear extinction by selective attention

Neuropsychologia. 2023 Sep 9:188:108627. doi: 10.1016/j.neuropsychologia.2023.108627. Epub 2023 Jun 20.

Abstract

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.

Keywords: Callosotomy; Corpus callosum; Dichotic listening; Laterality; Selective attention; Split brain.

MeSH terms

  • Attention
  • Auditory Perception
  • Dichotic Listening Tests*
  • Functional Laterality
  • Humans
  • Mental Recall
  • Prohibitins*

Substances

  • Prohibitins