When twice is better than once: increased liking of repeated items influences memory in younger and older adults

Background: Numerous studies have reported that the repeated presentation of a stimulus leads to an increase in positive affect towards the stimulus itself (the so-called mere exposure effect). Here, we evaluate whether changes in liking due to repetition may have a differential impact on subsequent memories in younger and older adults. Method: In two experiments, younger and older adults were asked to rate a series of nonwords (Experiment 1) or unfamiliar neutral faces (Experiment 2) in terms of how much they like them and then presented with a surprise yes–no recognition memory task. At study, items were repeated either consecutively (massed presentation) or with a lag of 6 intervening items (spaced presentation). Results: In both experiments, participants rated spaced repeated items more positively than massed items, i.e. they liked them most. Moreover, older adults remembered spaced stimuli that they liked most better than younger adults. Conclusions: The findings are discussed in accordance with the mechanisms underlying positivity effects in memory and the effect of repetition on memory encoding.