Visual Implicit Learning and Speech Recognition in Adult Post-Lingual Cochlear Implant Users

Implicit learning is thought to play an important role in speech recognition under challenging conditions. However, auditory deprivation has been proposed to influence implicit learning, including in the visual modality, although evidence in adults with post-lingual deafness is limited. Therefore, we investigated implicit visual learning and its associations with speech recognition in adults with post-lingual deafness who use cochlear implants (CIs). Thus, this study focuses on the effects of late auditory deprivation rather than on the effects of early deprivation associated with congenital deafness. Adult CI users (n = 30) and a group of individuals with normal hearing (NH, n = 36) completed two implicit visual learning tasks (statistical and perceptual), a battery of challenging speech recognition tests and cognitive measures (vocabulary, working memory, attention, and verbal processing speed). NH listeners demonstrated significant visual statistical learning, whereas CI users showed a similar but nonsignificant pattern. In the visual perceptual learning task, both groups exhibited comparable learning effects. In CI users, visual statistical learning contributed to the recognition of speech in noise (words and sentences). Visual perceptual learning only contributed to the recognition of words in noise. The current findings are inconsistent with the idea that auditory deprivation beyond the sensitive period interferes with visual learning. Rather, in CI users, visual implicit learning contributes to the recognition of challenging speech. Therefore, future work might investigate whether visual learning in CI candidates is predictive of postimplantation milestones.