Tone learning in aging: An encoding-enhanced training paradigm to promote overnight consolidation

Newly learned information is encoded as episodic memories during training and subsequently consolidated during overnight sleep. Previous research has found that Mandarin-speaking younger adults showed improved accuracy in learning novel Cantonese (contour) tones through six-block evening training after 12 h (i.e., overnight consolidation). However, age-related declines in tone encoding and sleep architecture may diminish the effect. Thus, this study examined older adults in two experiments, adopting six and lengthened ten blocks, respectively. Experiment 1 assessed overnight consolidation in older adults using the same paradigm for younger adults. 60 older Mandarin speakers were assigned to evening or morning training groups, matched in terms of sleep, hearing, and cognitive abilities. The key manipulation was that the evening training group slept between the immediate and 12-h delayed post-tests, whereas the morning controls remained awake during this interval. Neither group showed significant accuracy changes across post-tests, suggesting a lack of sleep-dependent consolidation effects. Experiment 2 then tailored a training paradigm, lengthening training to 10 blocks in 60 new participants to enhance encoding. The evening group improved in the delayed post-test compared to the immediate post-test, whereas the morning group maintained performance. Lengthened training enhanced older adults' encoding and facilitated overnight consolidation of Cantonese tones.