Fig. 2.

Results from the reference-back task. (a) Bar graphs indicating the mean behavioral cost (from RT data) in the L-tyrosine and placebo conditions, including standard error of the mean. (b) Pearson r correlations of placebo performance and the L-tyrosine minus placebo performance. On the x-axis, higher scores indicate greater behavioral costs. On the y-axis, positive scores indicate increased cost on L-tyrosine whereas negative scores indicate reduced cost. (c) Between-subject variance of the behavioral cost in the L-tyrosine and placebo conditions. *p < 0.05