Action-related variables in the effort task.

The three action-related dependent variables—choice (acceptance) rate (A), success rate (B), and exerted force (C) are shown as a function of target force level (imposed by the task). Only accepted trials were included in the analysis of success, and only successful trials in the analysis of force. Graphs show mean ± inter-subject SEM per force level. Darker colors and more continuous lines indicate bins (tertiles) of items with higher desirability ratings. Ratings were z-scored for every subject before binning.