Fig. 1.

The demand selection task. In a behavioral test of the DST (A), participants repeatedly chose between two stimulus locations. Choices tended to shift toward the low-demand location over the course of an experimental run (B); n = 12. Total low-demand selection rates varied (49–96% across subjects), and the DST showed internal consistency (α = 0.79) across its eight runs. The same pattern occurred in the DST administered following fMRI Experiment 2 (C); n = 22. Here again, individuals differed (D); single-subject bias rates exceeded chance for 10 participants (red data series), but not for the remaining 12 (black data series). Error bars show SEM.