Abstract Objectives This study investigated (a) whether the age-related enhancement in processing positive relative to negative emotional information happened at the early and/or late processing stages and (b) if the age-related positivity effect was modulated by cultural relevance using event-related brain potential (ERP). Methods Seventeen younger and 19 older Chinese adults judged the emotional valence of Chinese and Western pictures while electroencephalogram (EEG) was recorded and analyzed by temporospatial principal component analysis to dissociate the processing stages. Results (a) Larger N100 for negative than positive pictures was observed in younger, but not older adults, while older but not younger adults showed larger late anterior P300 for positive than negative pictures. (b) Older adults showed larger early posterior P300 for positive than negative Western pictures, but not culturally relevant Chinese pictures; such modulation effect by cultural relevance was absent in younger adults. Discussion These findings suggest an age-related decrease in sensitivity to negative information in the earlier stage and an age-related increase in sensitivity to positive information in the later stage of cognitive processing. This supports a dual-route model of the age-related positivity effect. Moreover, the age-related positivity effect is more evident for stimuli with less cultural relevance.