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Abstract:
It has been argued that the organisation of information in
semantic memory is preserved in older adults. Studies of semantic
priming, however, have reported age differences in the time course
of spreading activation and the attentional component of expectancy
generation. In the present study dense array (128 channel)
electroencephalography (EEG) was measured to investigate any
differences in the strategic processing of semantic information in
young adults (17-26 years) and healthy older adults (64-80 years).
Dense array EEG allows comparison of the latency and amplitude of
the event-related potential (ERP), and also detailed information
about the topography. Changes in ERPs were assessed while subjects
performed a semantic categorisation task on word stimuli. Eighteen
young adults and eighteen healthy older adults participated in the
study. Both young and older adults demonstrated a greater N400 to
unrelated items compared to related items. Age differences were
apparent in all three measures of the N400 component of the ERP.
The results support the hypothesis that age compromises the
efficiency of semantic processing in older adults. The results are
discussed in relation to changes in pre- and post-lexical semantic
processing which occur with increasing age.
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