Contextual interference effects in sequence learning for young and older adults.

Practice of different tasks in a random order induces better retention than practicing them in a blocked order, a phenomenon known as the contextual interference (CI) effect. Our purpose was to investigate whether the CI effect exists in sequence learning, such that practicing different sequences in a random order will result in better learning of sequences than practicing them in blocks, and whether this effect is affected by aging. Subjects practiced a serial reaction time task where a set of three 4-element sequences were arranged in blocks or in a random order on 2 successive days. Subjects were divided into 4 groups based on a 2-GROUP (young or old) by 2-ORDER (random or blocked practice) between-subject design. Three days after practice (Day 5), subjects were tested with practiced and novel sequences to evaluate sequence-specific learning. The results replicate the CI effect in sequence learning in both young and older adults. Older adults retained sequences better when trained in a random condition than in a blocked condition, although the random condition incurs greater task switching costs in older adults during practice. Our study underscores the distinction between age-related effects on learning vs. performance, and offers practical implications for enhancing skill learning in older adults.