Mice show sensitization to confined stereotypy by day 2 of D-amphetamine injection and tolerance by day 21 of treatment. Plots show rating of behaviors during the 80–82 min post-injection time period for locomotion (a; *P = 0.02, †P = 0.008, **P = 0.01, ††P = 0.01, by 2-tailed, paired t-tests), any confined stereotypy (b; *P = 0.01, †P = 0.008, **P = 0.004, ††P = 0.005), and confined sniffing or licking at the wall (c; *P = 0.02, †P = 0.003). Averages and +SEM across mice are shown, with individual mice identified by the symbol X.