The Effects of Structural Complexity on Age-Related Deficits in Implicit Probabilistic Sequence Learning

Objective. The primary objective was to determine whether age deficits in implicit sequence learning occur not only for second-order probabilistic regularities (event n − 2 predicts n), as reported earlier, but also for first-order regularities (event n − 1 predicts event n). A secondary goal was to determine whether age differences in learning vary with level of structure. Method. Younger and older adults completed a nonmotor sequence learning task containing either a first- or second-order structure. Learning scores were calculated for each subject and compared to address our research objectives. Results. Age deficits in implicit learning emerged not only for second-order probabilistic structure, but also for sim-ple, first-order structure. In addition, age differences did not vary significantly with structure; both first and second order yielded similar age deficits. Discussion. These findings are consistent with the view that there is an associative binding deficit in aging and that this deficit occurs for implicit as well as explicit learning and across simple and more complex sequence structures. Key Words: Aging—Implicit learning—Sequence learning—Structure. IMPLICIT learning refers to the ability to acquire environ-mental regularities without conscious effort or awareness of what has been learned (Reber, 1989). Implicit probabil-istic sequence learning is a specific type of implicit learn