From syllables to words: EEG studies on infants' language perception and language acquisition with a cochlear implant

We still know little about what infants and young children perceive after receiving a cochlear implant and how this influences subsequent language acquisition. In three longitudinal EEG studies and one follow-up study we investigate whether and when certain linguistic features are perceived via the implant in relation to the timeline of the actual word acquisition process.

EEG data were collected from children implanted bilaterally before their 4th birthday. Study 1 and Study 2 employed a classical oddball paradigm investigating the perception of vowel length and stress pattern differences in the first months after implantation. Study 3 and the follow-up study employed an N400 paradigm to investigate the formation of stable word-object relationships. A particular focus was placed on the results of congenitally deaf children.

Congenitally deaf children perceive differences in vowel length after 2 months of hearing experience and reach the level of typically hearing chronological age peers after 4 months. For stress pattern differences this is achieved after 6 months (4 months if not congenitally deaf). Stable word-object relationships are observable already after 12 months of hearing experience and thus even earlier than in typically hearing children of the same auditory age.

We thus conclude that basic auditory cues are not available immediately after implant activation but require a certain period of familiarization. By contrast, word acquisition relies more heavily on other cognitive faculties and is thus aided by the greater chronological age of the implanted children hence the faster word acquisition despite the poorer auditory input. The follow-up study will show whether the early EEG results correlate with later language performance at the age of 6 – 8 years.

Publication History

Publication Date:
23 April 2019 (online)