Age differences in implicit learning of probabilistic unstructured sequences.

OBJECTIVE It is unclear whether implicit probabilistic learning, the acquisition of regularities without intent or explicit knowledge, declines with healthy aging. METHODS Because age differences in previous work might reflect motor or rule learning deficits, we used the implicit Triplets Learning Task with reduced motor sequencing and non-rule-based associations. Fifteen young and 15 old adults responded only to the last event in a series of discrete 3-event sequences or triplets. A randomly chosen set of triplets occurred with high frequency, so there was no underlying rule to be learned. RESULTS Both age groups learned associative regularities, but age differences in favor of the young emerged with practice. Discussion. Age differences may reflect the different neural regions that are involved as training progresses, which differ in the extent to which they are compromised by aging.