Individual Differences in Lexical Access Among Cochlear Implant Users
Purpose: The current study investigates how individual differences in cochlear implant (CI) users’ sensitivity to
word–nonword differences, reflecting lexical uncertainty, relate to their reliance on sentential context for lexical
access in processing continuous speech.
Method: Fifteen CI users and 14 normal-hearing (NH) controls participated in an auditory lexical decision
task (Experiment 1) and a visual-world paradigm task (Experiment 2). Experiment 1 tested participants’ reliance
on lexical statistics, and Experiment 2 studied how sentential context affects the time course and patterns
of lexical competition leading to lexical access.
Results: In Experiment 1, CI users had lower accuracy scores and longer reaction times than NH listeners,
particularly for nonwords. In Experiment 2, CI users’ lexical competition patterns were, on average, similar to those of
NH listeners, but the patterns of individual CI users varied greatly. Individual CI users’ word–nonword sensitivity
(Experiment 1) explained differences in the reliance on sentential context to resolve lexical competition, whereas
clinical speech perception scores explained competition with phonologically related words.
Conclusions: The general analysis of CI users’ lexical competition patterns showed merely quantitative
differences with NH listeners in the time course of lexical competition, but our additional analysis revealed more
qualitative differences in CI users’ strategies to process speech. Individuals’ word–nonword sensitivity explained
different parts of individual variability than clinical speech perception scores. These results stress, particularly
for heterogeneous clinical populations such as CI users, the importance of investigating individual differences in
addition to group averages, as they can be informative for clinical rehabilitation.