Figure 2.

Open field (left panel) and the Y-maze (right panel). Chicks were placed in the center of the OF, and behavior was monitored for 10 min. The Y-maze apparatus consisted of one long arm and two short arms. The end compartment, goal box, of each short arm contained either a social stimulus or a foraging stimulus. The test chicken was placed in the start box, and the test of 10 min began when the guillotine door of the start box was pulled via a lever system. White chalk lines divided the apparatus in sub-compartments that could be used for analysis. Illustrations: Yorrit van der Staay.