Fig. 2. Wheel-running activity (revs day^–1 and km day^–1) in relation to workload during the workload phase. Filled circles represent mice facing low foraging costs (individual baseline), and open circles represent mice facing high foraging costs (2x individual baseline). Iso-reward lines show the activity required under different reward rates to obtain a constant amount of food (100% line) double intake (200% line) or reduce intake by half (50% line), ignoring cost of transport. Sample sizes per group were L=8, H=6 and R=7.