Acquisition and extinction of responding in Experiment 1. (a) Acquisition of procurement and consumption responding. (b) Procurement and consumption response rates during preprocurement, procurement, and consumption discriminative stimuli periods (preprocurement [Pre-SP], procurement [SP], and consumption [SC], respectively) during the final session of acquisition. (c) Elevation scores of Procurement response rates in 4-trial blocks across sessions of extinction. Error bars are the SEM, and only appropriate for between-groups comparisons.