Age and rate of activation in semantic memory.

Abstract

Two word-primed picture-naming experiments were carried out to test the hypothesis that rate of activation in semantic memory is slower for older adults than for young adults. The presence of priming effects, both positive and negative, was taken as evidence of activation. In Experiment 1 there was no age difference in the time of onset of either facilitation or inhibition by primes. A computer simulation, based on a simple connectionist model, showed that slower processing would have only a minimal effect on the time of onset of priming effects under the assumptions of the model; however, offset of inhibition by primes would be delayed if processing rate were reduced. In Experiment 2 older adults showed inhibition by primes over a longer interval than did young adults, which was taken as evidence that the general slowing associated with aging extends to the transmission of activation at the earliest levels of cognitive processing.

Age-related effects on speech production: A review

“…In some studies older adults show the same amount of lemma activation as young adults, as evidenced by age-equivalent effects of semantic priming and semantic interference (Bowles, 1994;Taylor & Burke, 2002;Tree & Hirsh, 2003), though in other studies semantic effects are larger in older than young adults (Taylor & Burke, 2002). The increased effect with age can be interpreted as consistent with general age-related slowing, with a specific deficit in lemma selection, or even with intact lemma selection.…”

“…A general finding of picture naming studies is that older adults are less accurate (Albert, Heller, & Milberg, 1988;Au, Joung, Nicholas, Obler, Kaas, & Albert, 1995;Barresi, Nicholas, Connor, Obler, & Albert, 2000;Hodgson & Ellis, 1998;Le Dorze & Durocher, 1992;Maylor, 1995;Nicholas, Obler, Albert, & Goodglass, 1985;Randolph, Lansing, Ivnik, Cullum, & Hermann, 1999) and slower than young adults (Bowles, 1994;Feyereisen, Demaeght, & Samson, 1998;Hodgson & Ellis, 1998;Maylor, 1995;Mitchell, 1989;Thomas, Fozard, & Waugh, 1977; but see Evrard, 2002;Poon & Fozard, 1978). It is less clear why this is the case.…”

“…(2) Lemma selection is largely preserved in old age, as evidenced by ageequivalent effects of semantic priming (Bowles, 1994) and semantic interference (Taylor & Burke, 2002) Taylor and Burke, 2002, for some evidence of larger priming with older individuals). In naming definitions, older adults know and produce the name of more definitions than young adults (Burke et al, 1991;Rastle & Burke, 1996;White & Abrams, 2002), which is further evidence that their knowledge of word meanings is intact.…”

“…Using a primed picture-naming paradigm, Bowles (1994) had young (aged 18-33 years) and older (aged 65-83 years) participants name pictures preceded by a masked, written word prime that was associatively related to the picture, by an unrelated prime, or by no prime (i.e., a blank screen). Stimulus onset asynchrony (i.e., the interval between onset of prime and onset of target, SOA) was manipulated by varying the duration of prime presentation from zero threshold, at which the prime could not be named, to full threshold, at which the prime could be named consistently.…”

A computational approach to modeling population differences

“…This two-step experimental procedure is the accepted methodology in measuring the performance of computational models, not merely for aging effects, but across different populations in general. The unmodified model represents a baseline level of functioning (often analogous to normal adult processing), and the modified model instantiates some theoretical alteration in order to bring model output in line with human results for that population.Another connectionist model of aging effects was implemented by Bowles (1994). In this study, the parameters of the model were adjusted to comply with the patterns exhibited by human participants.…”