The representation of ontological category concepts as affected by ageing: Normative data and theoretical implications.

Attributes associated with concept representations, such as familiarity, typicality and age of acquisition, have been shown to be important influences on lexical-semantic processing. In most previous studies of healthy and pathological ageing, these attributes are not equated for younger and older adults separately on the stimuli used. In this study, normative data were collected to test if there exist any age differences in these attributes. The results demonstrate that the ratings given by younger and older adults on natural and man-made category items correlated positively. However, age differences were also apparent, whereby older adults provided higher ratings overall than younger adults. Suggestions and hypotheses are presented to explain this pattern of age differences, which relate to how category concepts may be represented by healthy younger and older adults. Also, the possible implications for these differential age ratings on lexical-semantic processing are discussed. The age differences apparent in this study demonstrate the need to consider age-appropriate normative ratings in the selection of stimuli for use in lexical-semantic processing studies of ageing, and the normative data presented provide a means of equating category stimuli