Table 3.

Mean (±SEM) response rates (responses/s) on the levers associated with the large magnitude and small magnitude reinforcers during the initial and terminal links following psychostimulant administration.

Amphetamine
Dose	Initial Link - Large Reinforcer	Initial Link - Small Reinforcer	Terminal Link - Large Reinforcer#	Terminal Link - Small Reinforcer#
0 mg/kg	1.195 (0.066)	1.728 (0.129)	2.859 (0.264)	3.072 (0.407)
0.25 mg/kg	1.055 (0.107)	1.262 (0.118)	2.703 (0.320)	3.189 (0.406)
0.5 mg/kg*	0.792 (0.063)	0.932 (0.094)	2.001 (0.388)	1.938 (0.399)
1.0 mg/kg*	0.609 (0.070)	0.779 (0.088)	1.867 (0.422)	1.701 (0.514)
Methylphenidate
Dose	Initial Link - Large Reinforcer	Initial Link - Small Reinforcer^	Terminal Link - Large Reinforcer#	Terminal Link - Small Reinforcer#^
0 mg/kg	1.140 (0.122)	1.666 (0.203)	2.282 (0.258)	3.294 (0.329)
0.3 mg/kg	1.255 (0.087)	1.557 (0.064)	2.880 (0.322)	3.304 (0.389)
1.0 mg/kg	0.978 (0.085)	1.216 (0.145)	2.502 (0.317)	2.834 (0.298)
3.0 mg/kg	1.009 (0.098)	1.106 (0.141)	2.027 (0.293)	2.780 (0.308)
Methamphetamine
Dose	Initial Link - Large Reinforcer	Initial Link - Small Reinforcer	Terminal Link - Large Reinforcer#	Terminal Link - Small Reinforcer#
0 mg/kg	1.255 (0.134)	1.616 (0.109)	2.772 (0.221)	3.658 (0.348)
0.5 mg/kg*	0.750 (0.098)	0.757 (0.134)	2.076 (0.307)	2.412 (0.388)
1.0 mg/kg*	0.699 (0.194)	0.905 (0.321)	2.183 (0.333)	2.158 (0.431)
2.0 mg/kg*	0.416 (0.094)	0.517 (0.120)	1.362 (0.372)	1.082 (0.275)

^*p < .05, relative to vehicle (main effect of dose).

^#p < .05, relative to the terminal link (main effect of trial component).

^{^}p < .05, relative to the large, uncertain reinforcer (main effect of reinforcer).