Figure 1.

The number of responses per minute during baseline, choice, and no-choice sessions of the fixed-ratio (FR) assessment for Archer, Dennis, and Caleb are presented at top left. The total number of responses during choice and no-choice conditions of the progressive-ratio (PR) assessment for Archer, Dennis, and Caleb are presented at top right, with the breaking point (last schedule value completed) in parentheses above the data point for each session. Line-drawing rates across choice, no-choice, and control options during the concurrent assessment (Caleb only) are shown at bottom.