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Age-related differences in semantic-based generalization
Poster Session B, Friday, October 25, 10:00 - 11:30 am, Great Hall 3 and 4
Sao-Wei Chang1, Jinyi Hung1; 1MacKay Medical College, New Taipei City, Taiwan
Human semantic knowledge is generally considered preserved during aging. While differences between older and younger adults were often in other cognitive processes, degradation in semantic knowledge is typically pathological. It is thus assumed that healthy older adults receive good top-down knowledge support, which allows them to keep the boundary of the concepts clear and be able to overcome bottom-up surface interference. Here we assessed to what extent did the healthy older adults did in making semantic judgment that relied heavily on top-down processing. We also compared their performance to a group of younger adults to examine the effect of aging on semantic processing. Eighteen older adults (mean age = 64.2, mean edu = 12.6) and 10 younger adults (mean age = 21.1, mean edu =14.1) completed a word-to-picture matching task in which participants were asked to select which items, from an array of 8 pictures, were examples of the probe word. Following Lambon Ralph et al. (2010), we included typical, atypical, pseudotypical, partially related, same category, and unrelated exemplars to test the effect of typicality and surface similarity. We also tracked participants’ eye movements during the task and set each exemplar as an area of interest (AOI) to examine participants’ online performance. Group comparisons were performed to examine the accuracy and eyetracking metrics among exemplars. The results showed that relative to the younger adults, older adults were more likely to select atypical and pseudotypical exemplars (atypical t(46) = 1.97, df = 46, p = 0.05; pseudotypical t(46) = 3.25, p = 0.002). Eyetracking results also showed that overall older adults had slower time to first fixation (mean diff = 891, F(1) = 97.04, p <0.01) and greater number of fixations (mean diff = 0.56, F(1) = 18.88, p <0.01) among exemplars; especially in the atypical, partial, and the pseudotypical ones. Older adults spent more time viewing the exemplars, but their performance was comparable with the younger adults. It shows that the difference between older and younger adults may mainly be the speed of processing and not necessarily the degradation of the knowledge itself. On the one hand, older adults were more likely to correctly identify atypical exemplars; together with their performance in correctly excluding partial and same category exemplars, it seems that older adults benefit from well knowledge support and are more lenient to concepts. On the other hand, older adults tend to incorrectly include pseudotypical exemplars, showing that they were more likely to be confused by the surface similarity than the younger adults. These findings suggest that older adults have different semantic processes from younger adults, although older adults still maintain good boundary of concepts, they are more likely to be influenced by bottom-up surface similarity.
Topic Areas: Meaning: Lexical Semantics,