Effects of amphetamine on RGT performance. A) Trained animals, and Acquisition sham animals displayed a main effect of dose, with significant increases in choice of the 1-pellet option at 1.0 and 1.5 mg/kg (p’s = 0.001), however, Acquisition TBI animals were only significant at the 1.0 mg/kg dose (p = 0.039). B) Trained animals, and Acquisition sham animals significantly decreased choice of the 2-pellet option at 1.0 and 1.5 mg/kg (p’s < 0.001), while Acquisition TBI animals did not significantly change preference. C) Trained animals showed no effect of dose on 3-pellet choice. Acquisition sham animals increased preference at the 1.5 mg/kg dose (p = 0.035). D) Trained animals showed no effect of dose on 4-pellet choice. Acquisition sham animals increased preference at the 1.0 mg/kg dose (p = 0.021). E) Trained TBI animals significantly decreased premature responding compared to Trained shams at the 1.0 mg/kg dose (p = 0.007), while Acquisition animals showed no effect. F) There was an overall effect of dose on omissions for Acquisition animals, but no significant differences relative to saline. Data are mean + SEM.