Table 1.

Example training timetable for a given animal during cocaine-food choice. Note: Order of conditions (food restriction, removal of cocaine cues, and removal of head-entry orienting responses) within the experiment proper was scheduled according to a partial Latin-square design (baseline first), and some animals had up to 5 additional days within a given condition to establish stability. During controlled reinforcer frequency sessions the cocaine:food reinforcer frequency ratio used was constant at 3:3. See the supplemental methods for details regarding the initial training phases.

Initial Training	Days
Magazine shaping	2
Lever training	8
Orienting response	3
Catheter surgery and recovery	8
Drug self-administration training	8
Drug-food lever training	4
Experiment Proper	Days
Baseline Controlled Reinforcer Frequency (3:3)	14
Food restriction - controlled reinforcer frequency (3:3)	10
Baseline - controlled reinforcer frequency (3:3)	7
No cocaine cues - controlled reinforcer frequency ratio (3:3)	10
Baseline - controlled reinforcer frequency ratio (3:3)	7
No head-entry orienting response - controlled reinforcer frequency ratio (3:3)	10
Baseline Uncontrolled Reinforcer Frequency	14
Food restriction - uncontrolled reinforcer frequency	10
Baseline - uncontrolled reinforcer frequency	7
No cocaine cues - uncontrolled reinforcer frequency	10
Baseline - uncontrolled reinforcer frequency	7
No head-entry orienting response - uncontrolled reinforcer frequency	10