Figure 3.

Lipping behavior. A, Representative examples of lipping behavior. In cued trials, lipping in the six conditions (three reward sizes × active vs Passive) is plotted around cue onset (left) and feedback (middle). Right, Lipping around the feedback in the three conditions (three reward sizes) of the self-initiated trials. Data from cued and self-initiated trials were collected separately. Each line is the signal from one trial. For lipping at the cue, passive trials are sorted by time (first at the top), and active trials are sorted by increasing trial duration. For lipping at the feedback, trials are sorted by increasing time between the feedback (t = 0, vertical line) and reward delivery (light blue symbols). For each reward size condition, average signals for all trials (±SEM) are shown below raw traces. In cued trials, average traces for active (red) and passive (orange) trials are plotted separately. The lipping at the cue increases with reward size, with virtually no difference between active and passive trials. At the feedback, lipping is stronger and begins earlier in cued active than in cued passive trials, with little effect of reward size. In self-initiated trials, lipping around the feedback increases with reward size. B, Percentage of lipping responses across conditions for each monkey (mean ± SEM). Left, In cued trials, the proportion of lipping responses to cues increased with reward size, with no difference between active and passive trials. Middle, At the feedback in cued trials, lipping responses were significantly more frequent in active than in passive trials, with little effect of reward size. Right, In self-initiated trials, the percentage of lipping responses increased for larger rewards.