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.