| By its very nature the human language system must be flexible, i.e., allow for production of unique combinations of items. The cost of this flexibility is the potential for speech errors. The purpose of this research was to examine age-related changes in speech production on laboratory induced slips of the tongue (phonological errors, e.g., exchange, anticipation, perseveration) produced by 32 young adults (18-35 years) and 32 older adults (60-85 years). The methodology for generating speech errors, used here for the first time with older adults, was based on the SLIP technique developed by Baars, Motley, and MacKay (1975). The SLIP technique elicits a type of verbal slip known as a spoonerism, i.e., unintentional switching of speech sounds (phonemes) in spoken language (e.g., the intended utterance darn bore being accidentally transformed into barn door).; Currently there are two hypotheses about cognitive aging which include predictions relevant to language production, namely the transmission deficit hypothesis (MacKay & Burke, 1990) and the inhibition deficit hypothesis (Hasher & Zacks, 1988). MacKay and Burke suggest that aging reduces the rate and amount of priming during speech production. Hasher and Zacks propose a general theory of age-linked changes in inhibitory processes, arguing that older adults' ability to suppress irrelevant information is impaired. Both accounts predict more speech errors for older adults than young adults. However, the transmission deficit hypothesis also makes specific predictions about age-related differences depending on the type of phoneme exchange error (e.g., anticipation, perseveration), word or nonword errors, and error detection.; Older adults produced significantly more errors than young adults. The largest proportion of errors for both age groups was reading errors, which were generally phonologically or orthographically similar to one or both words of the cued pair (e.g., binge {dollar}to{dollar} beige). However, contrary to the prediction of the transmission deficit hypothesis, older adults did not have a lower proportion of anticipation errors than young adults. As predicted by the transmission deficit hypothesis, older adults were less likely to detect their errors. |
