Aging effects on the ERP correlates of involuntary attentional capture in speech sound analysis

In an auditory oddball paradigm, 16 old and 16 young adults were asked to ignore binaurally presented disyllabic speech sounds and to watch a silent movie while event-related potentials (ERPs) were recorded. Four types of phonetic deviants occurred on, respectively: (1) the Stressed-First syllable, (2) the Unstressed-First syllable, (3) the Stressed-Second syllable and (4) the Unstressed-Second syllable. The nature of the phonetic change was the same across the four deviants. A P3a was seen only for deviant 3 in the elderly while observed for deviants 1 and 3 in the young. The mismatch negativities (MMNs) to deviants 1 and 2 were reduced compared with those to the other two deviants in both age groups. It is concluded that the ability to use salient prosody to involuntarily capture attention for speech sounds is preserved in normal aging. The lack of P3a response to deviant 1 in the elderly may result from the combined effects of backward masking and age-related temporal encoding inefficiency as indicated by reduced MMNs for the elderly.