Using behavioral data to model open-set word recognition and lexical organization by pediatric cochlear implant users.

Abstract

Children who acquire language through a cochlear implant (CI) provide a unique opportunity to study the physical and cognitive bases of speech perception, as the target language these children must acquire is the same as for children without hearing loss, but the input to the nervous system from a CI is very different from normal hearing. Psycholinguistic models of speech perception in adults with normal hearing propose that the phonological lexicon is organized in a phonetic similarity space based on linguistic features and phonemes, and that these units are important for spoken word recognition. Although the physical signal received through a CI is different from aurally perceived speech, we propose that the same abstract units of language are nonetheless a part of the linguistic knowledge of children who learn spoken language through CIs. In this paper, we model performance by children with CIs on tests of open-set word recognition using their performance on closed-set tests of feature identification. Our model of word recognition does not employ any free parameters, and therefore is highly constrained. Modeling the cognitive process of spoken word recognition on the basis of feature identification performance is important to both theoretical and clinical research. The model of word recognition we propose is appropriate for both listeners who use CIs and those with normal hearing. It is therefore a theoretical model of the process of spoken word recognition in general, as well one way to address the question of whether the cognitive process of spoken word recognition is the same for both CI users and those with normal hearing. Comparing observed and predicted open-set word recognition performance from closed-set identification tasks may be particularly useful clinically for the pediatric CI population. If differences between observed and predicted performance can be attributed to particular components of the model, then it may be possible to provide intervention that is maximally beneficial to the child.