Sequencing, Speech Production, and Selective Effects of Aging on Phonological and Morphological Speech Errors.

Abstract

To test age-linked predictions of node structure theory (NST) and other theories, young and older adults performed a task that elicited large numbers of phonological and morphological speech errors. Stimuli were visually presented words containing either /p/ or /b/, and participants changed the /p/ to /b/ or vice versa and produced the resulting word as quickly as possible. For example, the correct response was "bunk" for the stimulus PUNK, and "ripped" for RIBBED. Consistent with NST predictions, the elicited speech errors exhibited selective effects of aging. Some error types decreased with aging. For example, young adults produced more nonsequential substitution errors (as a percentage of total errors) than older adults (e.g., intended bills misproduced as "gills"). However, other error types remained constant or increased with aging. For example, older adults produced more omission errors than young adults, especially omissions involving inflectional endings (e.g., intended ripped misproduced as "rip"). In addition, older adults exhibited special difficulties with 2 types of phonological and morphological sequencing processes.1 To distinguish spoken (phonological) units from written (orthographic) units, we follow the usual convention of indicating phonological units in International Phonetic Alphabet transcription within slashes (e.g., /p/) and orthographic units within square brackets (e.g., [P]). The stimulus words are indicated in capital letters.

Age-related changes in the functional neuroanatomy of overt speech production

“…These age-related impairments in speech production are likely related to a decline in oro-facial motor control, as shown by decreased accuracy of movement amplitudes and increased temporal variability of movements (Ballard et al, 2001), as well as impairment of phonological processing, in particular the sequencing of phonological units (MacKay and James, 2004). Based on these behavioral findings and the results of previous functional brain imaging studies in younger adults, the aim of the present study was to compare the neural correlates of overt speech production between healthy older and younger adults using simple non-lexical utterances with varying complexity.…”

New age-linked asymmetries: Aging and the processing of familiar versus novel language on the input versus output side.

“…Present results therefore add to numerous other demonstrations of selective rather than across-the-board age-linked deficits in phonological and lexical-level processing. To illustrate one recent demonstration, consider the impact of aging on experimentally induced phonological speech errors in MacKay and James (2004): Compared with young adults, phonological speech errors of older adults contained relatively more omissions and order errors but relatively fewer substitutions of correctly ordered speech sounds. This age-linked error-type asymmetry indicates another selective rather than across-the-board effect of aging at phonological levels.…”

“…However, age-linked production deficits are not confined to phonological levels of language production. To illustrate, consider morphological speech errors, for example, the word pans misproduced as "pan" where the plural morpheme has been omitted: MacKay and James (2004) demonstrated an age-linked increase in phonological speech errors involving morphemes relative to ones not involving morphemes (e.g., pant misproduced as "pan").…”

Academic Press is an imprint of Elsevier

“…No differences between older and younger adults in detection accuracy were observed. However, older adults were less accurate on the production task, in which participants had to write out the words they had seen, because they misspelled words they had correctly rejected in the comprehension task [also see MacKay and Abrams (1998) MacKay and James (2004) and Stuart-Hamilton and Rabbitt (1997) for similar studies of age-related changes in spelling, as well as Abrams and Stanley (2004), for evidence that even spelling comprehension is impaired in very old adults]. This production-comprehension asymmetry has been demonstrated across a variety of tasks (Burke & MacKay, 1997).…”

“…The inhibition deficit hypothesis proposes that aging weakens inhibitory processes so that older adults are less able to suppress irrelevant information than younger adults Zacks & Hasher, 1997). An alternative theory, the transmission deficit account, hypothesizes that many agerelated changes in linguistic processes stem from weakened connections among memory representations that reduce the transmission of excitation, resulting in weakened patterns of activation (Burke et al, 1991;MacKay, Abrams, & Pedroza, 1999;MacKay & James, 2004).…”