Effects of aging and noise on real-time spoken word recognition: evidence from eye movements.

PURPOSE To use eye tracking to investigate age differences in real-time lexical processing in quiet and in noise in light of the fact that older adults find it more difficult than younger adults to understand conversations in noisy situations. METHOD Twenty-four younger and 24 older adults followed spoken instructions referring to depicted objects, for example, "Look at the candle." Eye movements captured listeners' ability to differentiate the target noun (candle) from a similar-sounding phonological competitor (e.g., candy or sandal). Manipulations included the presence/absence of noise, the type of phonological overlap in target-competitor pairs, and the number of syllables. RESULTS Having controlled for age-related differences in word recognition accuracy (by tailoring noise levels), similar online processing profiles were found for younger and older adults when targets were discriminated from competitors that shared onset sounds. Age-related differences were found when target words were differentiated from rhyming competitors and were more extensive in noise. CONCLUSIONS Real-time spoken word recognition processes appear similar for younger and older adults in most conditions; however, age-related differences may be found in the discrimination of rhyming words (especially in noise), even when there are no age differences in word recognition accuracy. These results highlight the utility of eye movement methodologies for studying speech processing across the life span.