Figure 2.

Pictures of the three mazes used in these experiments. (A) The ramp maze shown from the top with all gates in the up position. Reward platforms are in upper left and right and small circles are feeder wells. Both ramps are at their lowest position. (B) Close up of the left ramp in an elevated position showing the vertical ramp that rats climbed to reach reward and sloped return ramp. (C) Top view of the weighted lever apparatus showing a rat coming from the base arm and deciding which lever arm to choose. The dark bar is the lever and the small circle near the lever end is the feeder well. (D) A rat on the exposed arm of the courage maze. Reward well is located at the far right, just beyond the field of view. The enclosed safe arm is also visible.