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. Author manuscript; available in PMC: 2010 Sep 21.
Published in final edited form as: Pharmacol Biochem Behav. 2007 Nov 6;89(1):17–22. doi: 10.1016/j.pbb.2007.10.017

Fig. 1.

Fig. 1

Comparison between Sprague–Dawley (SD) and Fischer 344 (F344) rats in responding for food reinforcement revealed a significant effect of strain and days of training. Student Newman–Keuls posthoc analysis showed significantly more lever pressing in the SD than the F344 strain on days 2, 3, 4, and 5 (*p< 0.001). SD rats which attained lever pressing criterion prior to day 5 were included in the statistical analysis as a mean group/day substitution performance score for days 4 and 5 (total of 2 observations for day 4 and 9 observations for day 5).