Late maturation of auditory perceptual learning

Abstract

Adults can improve their performance on many perceptual tasks with training, but when does the response to training become mature? To investigate this question, we trained 11-year-olds, 14-year-olds and adults on a basic auditory task (temporal-interval discrimination) using a multiple-session training regimen known to be effective for adults. The adolescents all began with performance in the adult range. However, while all of the adults improved across sessions, none of the 11-year-olds and only half of the 14-year-olds did. The adolescents who failed to learn did so even though the 10-session training regimen provided twice the number of sessions required by adults to reach asymptotic performance. Further, over the course of each session, the performance of the adults was stable but that of the adolescents, including those who learned, deteriorated. These results demonstrate that the processes that underlie perceptual learning can continue to develop well into adolescence.

Figure 1

Across-session performance of adults, 14-year-olds, and 11-year-olds. (a–c) Average group results: Mean temporal-interval discrimination thresholds (Δt for 79.4% correct) for the trained (filled triangles) and control groups (open squares) at the pre- and post-training tests, and the trained groups during the training phase. Results are shown separately for the adults (a), 14-year-olds (b), and 11-year-olds (c). Only the trained adults learned gradually across training sessions and improved more than same-age controls between the pre- and post-training tests. (d–f) Learners vs. non-learners: Mean temporal-interval discrimination thresholds for each trained group, divided into learners (open circles) and non-learners (filled circles) based on each listener’s training phase performance. The proportion of learners in each group became greater with increasing age. Error bars indicate ± one standard error. Trained groups: adult, n = 6, all learners; 14-year-olds, n = 8, 4 learners; 11-year-olds, n = 5, all non-learners. Control groups: adult, n = 9; 14-year-olds, n = 4; 11-year-olds, n = 6.

Figure 2

Within-session performance of adults, 14-year-olds, and 11-year-olds. (a–d) Mean values for the first and last three threshold estimates of each training session. Results are shown separately for the adults (a), 14-year-old learners (b), 14-year-old non-learners (c), and 11-year-olds (d). Groups that learned across sessions are represented by filled circles and those that did not learn across sessions are represented by open circles. Error bars indicate ± one standard error.