RECOGNIZING SPOKEN WORDS - THE NEIGHBORHOOD ACTIVATION MODEL

Objective: A fundamental problem in the study of human spoken word rec ognition concerns the structural relations among the sound patterns of words in memory and the effects these relations have on spoken word r ecognition. In the present investigation, computational and experiment al methods were employed to address a number of fundamental issues rel ated to the representation and structural organization of spoken words in the mental lexicon and to lay the groundwork for a model of spoken word recognition. Design: Using a computerized lexicon consisting of transcriptions of 20,000 words, similarity neighborhoods for each of t he transcriptions were computed. Among the variables of interest in th e computation of the similarity neighborhoods were: 1) the number of w ords occurring in a neighborhood, 2) the degree of phonetic similarity among the words, and 3) the frequencies of occurrence of the words in the language. The effects of these variables on auditory word recogni tion were examined in a series of behavioral experiments employing thr ee experimental paradigms: perceptual identification of words in noise , auditory lexical decision, and auditory word naming Results: The res ults of each of these experiments demonstrated that the number and nat ure of words in a similarity neighborhood affect the speed and accurac y of word recognition. A neighborhood probability rule was developed t hat adequately predicted identification performance. This rule, based on Luce's (1959) choice rule, combines stimulus word intelligibility, neighborhood confusability, and frequency into a single expression. Ba sed on this rule, a model of auditory word recognition, the neighborho od activation model, was proposed. This model describes the effects of similarity neighborhood structure on the process of discriminating am ong the acoustic-phonetic representations of words in memory. The resu lts of these experiments have important implications for current conce ptions of auditory word recognition in normal and hearing impaired pop ulations of children and adults.