Age-related differences in fixed versus roving AX discriminations

Abstract

The present study examines age-related differences in the discrimination of vowels and consonants (using both AX fixed and roving paradigms). Two groups of listeners—including young adults (mean age 23.9 yr) and older adults (mean age 67.8 yr)—were required to identify and/or discriminate tokens from either a [i]-[eh] vowel continuum or a [bopen aye]–[dopen aye] consonant continuum. The two groups were matched for auditory sensitivity. As expected, for both groups consonant responses were more ‘‘categorical’’ than were vowel responses. Fixed discrimination was also better than roving discrimination (although the effect was only significant for the consonant stimuli). In terms of age differences, discrimination performance tended to be better for younger listeners in most conditions, although these differences did not reach statistical significance. However, there was a significant age by task paradigm interaction for the consonant stimuli. Although the younger listeners showed significantly poorer discrimination in the roving vs. fixed condition, there was no such difference for the older listeners. Discriminations by older listeners were also more affected by the location of the category boundaries than were those of younger listeners. [Work supported, in part, by the National Institute on Aging Grant No. 5R01 AG08353.]