ObjectivesOne key challenge in word recognition is the temporary ambiguity in the signal created by the fact that speech unfolds over time. Research with normal hearing (NH) listeners reveals that this temporary ambiguity is resolved through incremental processing of the signal and competition among possible lexical candidates. Post-lingually deafened cochlear implant (CI) users show similar incremental processing and competition to NH listeners but with slight delays. However, even brief delays could lead to drastic changes when compounded across multiple words in a sentence. This study asks whether words presented in non-informative sentence contexts are processed differently than words presented in isolation and whether any differences are shared among NH listeners and CI users or if the groups exhibit different patterns.DesignAcross two visual world paradigm experiments, listeners heard words presented either in isolation or in non-informative sentence contexts (“click on the…”). Listeners selected the picture corresponding to the target word from among four items including the target word (e.g., mustard), a cohort competitor (e.g., mustache), a rhyme competitor (e.g., custard), and an unrelated item (e.g., penguin). During this task, eye movements were tracked as an index of the relative lexical activation of each object type during word recognition. Subjects included 65 CI users and 48 NH controls across both experiments. ResultsBoth CI users and the NH controls were largely accurate at recognizing the words both in sentence contexts and in isolation. The time course of lexical activation (indexed by the fixations) differed substantially between groups. CI users were delayed in fixating the target relative to NH controls. Additionally, CI users showed less competition from cohorts (while previous studies have often found increased competition) compared to NH controls. However, CI users took longer to suppress the cohort and suppressed it less fully than the NH controls. For both CI users and NH controls, embedding words in sentences led to more immediacy in lexical access as observed by increases in cohort competition relative to when words were presented in isolation. However, CI users were not differentially affected by the sentencesConclusionsUnlike prior work, in both sentences and in isolated words CI users appeared to exhibit “wait-and-see” strategy, in which lexical access is delayed to minimize early competition. However, they simultaneously sustain competitor activation late in the trial possibly to preserve flexibility. This hybrid profile has not been observed previously. Both CI users and NH controls more heavily weight early information when target words are presented in sentence contexts. However, CI users (but not NH listeners) also commit less fully to the target when words are presented in sentence context potentially keeping options open if they need to recover from a misperception. This mix of patterns reflects a lexical system that is extremely flexible and adapts to fit the needs of a listener.
The influence of sentence context and accented speech on lexical access in second-language auditory word recognition
