Modeling spoken word recognition performance by pediatric cochlear implant users using feature identification.

OBJECTIVE: Computational simulations were carried out to evaluate the appropriateness of several psycholinguistic theories of spoken word recognition for children who use cochlear implants. These models also investigate the interrelations of commonly used measures of closed-set and open-set tests of speech perception. DESIGN: A software simulation of phoneme recognition performance was developed that uses feature identification scores as input. Two simulations of lexical access were developed. In one, early phoneme decisions are used in a lexical search to find the best matching candidate. In the second, phoneme decisions are made only when lexical access occurs. Simulated phoneme and word identification performance was then applied to behavioral data from the Phonetically Balanced Kindergarten test and Lexical Neighborhood Test of open-set word recognition. Simulations of performance were evaluated for children with prelingual sensorineural hearing loss who use cochlear implants with the MPEAK or SPEAK coding strategies. RESULTS: Open-set word recognition performance can be successfully predicted using feature identification scores. In addition, we observed no qualitative differences in performance between children using MPEAK and SPEAK, suggesting that both groups of children process spoken words similarly despite differences in input. Word recognition ability was best predicted in the model in which phoneme decisions were delayed until lexical access. CONCLUSIONS: Closed-set feature identification and open-set word recognition focus on different, but related, levels of language processing. Additional insight for clinical intervention may be achieved by collecting both types of data. The most successful model of performance is consistent with current psycholinguistic theories of spoken word recognition. Thus it appears that the cognitive process of spoken word recognition is fundamentally the same for pediatric cochlear implant users and children and adults with normal hearing.

Training generalized receptive prepositions in retarded children.

THREE RETARDED CHILDREN WERE TRAINED, USING PROMPTING AND REINFORCEMENT PROCEDURES, TO RESPOND CORRECTLY TO THREE CATEGORIES OF PREPOSITIONAL REQUESTS: "put the-next to the-", "put the-under the-", and "put the-on top of the-". Training sessions were alternated with probe sessions throughout the study. During training, a child was trained to respond to one request (e.g., "put the doll next to the cup"); during probing, the child was tested for generalization of this training to untrained requests. Responses to untrained requests were never prompted nor reinforced. The results showed that, as requests from one category were trained, the children's responses to the untrained requests of that category became increasingly correct. As discriminations among two or more categories were trained, the children's responses to the untrained requests of those categories also became increasingly correct. Thus, the methods employed appear to be successful in training generalized receptive discrimination among prepositional categories and possibly can be utilized in training other generalized receptive language skills.