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

Abstract

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 simple, 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.

Keywords: Aging; Implicit learning; Sequence learning; Structure..

Figure 1.

Schematic of the Triplets Learning Task. Each trial, or “triplet,” consists of the sequential presentation of two red cues and a green target. Subjects are instructed to view the first two red cues of each triplet and to respond only to the location of the green target using a corresponding response button.

Figure 2.

Mean Implicit Associative Learning scores for young and older adults separated by structure and session. Means that are significantly different (p < .05) are denoted with an *.