Attribute-based similarity perception in younger and older adults.

The use of organization changes quantitatively and qualitatively during adulthood. Organization into categories is typically based on similarity relations which are in turn based on the comparison of object features; therefore, the impact of the featural representation of objects on similarity perception was examined. Groups of younger and older adults of comparable verbal ability generated descriptions of twelve objects from one of two taxonomic categories and then rated the similarity of all possible pairs of the twelve objects. Minimal age differences were found in the qualitative types of features used to describe objects. The relationship between these featural descriptions and similarity judgments, on the other hand, was found to change somewhat with age. Measures of common and distinctive features predicted substantial percentages of the variance in similarity ratings for both age groups, though these variables accounted for more variance in the similarity ratings of the younger group. The significant predictors of similarity ratings included relatively more perceptual feature measures for younger adults, but relatively more function-related feature measures for older adults. Also, older adults depended relatively more on distinctive features in making their similarity judgments.