Effects of age on retrieval cue processing as revealed by ERPs

The electrophysiological correlates of retrieval cue processing were investigated in healthy young (18-30 years) and older (63-75 years) subjects (n = 16 per group). Retrieval orientation--the differential processing of cues according to the form of the sought-for information--and retrieval difficulty were manipulated in a factorial design. In separate study-test cycles, subjects studied either words or pictures, and performed a yes/no recognition memory task with words as the test items. ERPs elicited by correctly classified new words differed markedly according to study material in the young subjects, replicating previous findings. In the older subjects, this effect was smaller than in the young, and had a later onset and earlier offset. The scalp topography of the effect was however statistically indistinguishable in the two groups. These age-related ERP differences were unmodulated by task difficulty, and remained reliable when recognition performance was matched across the groups. By contrast, the magnitude and timing of ERP difficulty effects were unaffected by age. The findings suggest that older subjects are less able than young individuals to vary their processing of retrieval cues in response to different retrieval demands.