AGING AND AUTOMATICITY - EVALUATION OF INSTANCE-BASED AND STRENGTH-BASED MECHANISMS

Experiments evaluated instance-based learning as a possible sole mecha nism underlying development of automaticity. Age differences in extend ed practice lexical decision and factors that could effect age-related performance on lexical decision tasks were also examined. The first e xperiment was conducted to evaluate the role of stimulus-specific and strategic, task-specific learning underlying performance improvement i n a trained lexical decision task. The first experiment consisted of a training and a transfer phase. The training phase assessed age-relate d differences on a lexical decision task where an attention response c ould, in principle, be developed (Search condition) and where an atten tion response could not develop (Nonsearch condition). The transfer ph ase was conducted to evaluate the role of strategic, task-specific fac tors on performance improvement observed in the training phase. Age-re lated differences in word-nonword response time differences were elimi nated with practice in the nonsearch, but not the search, version of t he task. Transfer tests also implicate strategic differences as a part ial source of age differences in lexical decision performance. Experim ent 2 was a 10-session (two-week) extended practice study which was co nducted to provide a strong test of instance-based learning as a sole mechanism for automaticity. Contrary to predictions of instance theory , the Search and Nonsearch conditions converged for the young adults. Consistent with a strength-based theory of automaticity applied to cog nitive aging, the conditions did not converge for older adults. The re sults provide further support for age differences in automaticity-as-a ttention training. Based on these and other results, the importance of considering varieties of automaticity in theories of cognitive aging is discussed.