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. Author manuscript; available in PMC: 2016 Jul 1.
Published in final edited form as: Psychopharmacology (Berl). 2015 Feb 8;232(13):2393–2403. doi: 10.1007/s00213-015-3871-8

Figure 2.

Figure 2

Normalized demand curves for 0.01 mg/kg/inj nicotine and 0.03 mg/kg/inj cocaine. The abscissa is the unit price for the drugs, and the ordinate is the number of injections taken at each ratio value as percent of the number of injections taken at FR 10 (± SEM). Demand curves are plotted separately for nicotine (diamonds), cocaine (triangles), those monkeys that self-administered nicotine in the FR or TO experiments (solid symbols and solid lines), and those monkeys that did not self-administer nicotine (open symbols and dashed lines).