The Relation Between Early Word Stress Discrimination and Later Lexical Development

A key component of early intervention for children with delayed language acquisition is early assessment. Previous research has shown that English-learning infants’ sensitivity to lexical stress plays a role in their segmentation of words from fluent speech – a critical step to developing a lexicon. This study investigated the possibility that performance on a word stress discrimination task predicts later lexical development for normal-hearing infants. A version of the visual habituation procedure (VHP) was used to test infants’ ability to discriminate two-syllable words with trochaic versus iambic stress patterns (trochaic being most common in English). Infants were first habituated to recorded lists of words with either trochaic or iambic stress patterns and then presented with words of the habituated stress pattern and words of the novel stress pattern. Infants’ attention towards the novel stress pattern was measured by looking duration in seconds and compared to their looking durations during the presentation of the habituated stress pattern. Longer looking times to the novel stress pattern suggests discrimination of the stress patterns. To assess lexical development, the MacArthur Bates Communicative Development Inventory (CDI) was administered at twelve months of age. Overall, infants showed a high degree of variability on both the discrimination task and the CDI measures. As a group, infants habituated to words following trochaic and iambic stress patterns but did not demonstrate the ability to discriminate between the novel and familiar stress patterns. There was no significant relationship between the ability to discriminate and the CDI measures. These results suggest that there is not a relationship between early word stress discrimination and later lexical development. Future work will aim to determine the degree of influence word stress discrimination has on later language acquisition.More specifically, future work will compare word stress discrimination ability in infant directed speech to later language development.