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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 1.

Figure 1

Rates of responding for 0.03 mg/kg/inj cocaine (▲) or 0.003 to 0.03 mg/kg/inj nicotine (■), and saline (○) in eight monkeys as a function of the size of the fixed ratio schedule of drug reinforcement.