Behavioral adaptation to cost evidence.

<p>The three columns (A, B and C) present three different studies, with results underneath the tasks. Note that there are two sub-columns for the last study (on the right) because there are two dependent variables (rest and effort duration). Top: Behavioral tasks. Each plot sketches the variations of exerted force level within a trial. Gray shading indicates the periods when action was imposed on participants; in the other periods the behavior was let free. The broken line points to periods when durations were systematically varied. Bottom: Relation between imposed and observed group-level average durations (± SEM). Two data points are plotted for each imposed duration, corresponding to left and right hands. The black line is the group average of the model fit estimated at the subject level; dash lines indicate the 95% confidence interval of the average.