Figure 3.

Chicks were located in a rectangular enclosure immediately after hatching in darkness, and presented (t indicates time) with an object moving (a) and hiding behind a grid placed in a corner (b). Chicks were then spatially disoriented by slowly rotating them in darkness and four identical replicas of the object were located in each corner (c) partly visible behind the grids. At test, chicks oriented by using the metric arrangement of the surfaces together with the left–right directional sense, choosing the two geometrically correct corners (yellow (dark grey in print) and grey chicks in (d) (see [18]). (Online version in colour.)