Fig. 1.

T-maze test apparatus consisting of a Perspex tunnel and attached wooden start-box. The tunnel connects the two pens in the experimental room. A indicates the wooden side-doors of the start-box which were removed to reveal wire mesh, through which the goal(s) could be viewed. B indicates the tunnel-door, which was raised using a pulley mechanism to allow access to the tunnel. C marks the pen-door (shown as closed) which was placed in the pen entrance once the hen entered the pen, to prevent her from re-entering the tunnel.