Fish Reorient Specifically by Distance Relationships in the 3D Surface layout

Studies of spatial navigation in both humans and nonhuman animals refer to sensitivity to the environmental shape for reorientation as a “geometric” computation underlying navigation. However, the exact geometric representations captured by these processes are not specified. Recent studies with two-year-old children revealed spontaneously reorientation in accord with surface distances and directions but fail to use surface lengths or corner angles1 . The present study teases apart reorientation by geometric properties in zebrafish, who have been shown to spontaneously reorient by rectangular geometry 2 . After first establishing that fish reorient by rectangular geometry in an opaque tank (Full Rectangle) but not a transparent one (surrounded by a circular, geometrically uninformative space), we isolated distance and length properties of the rectangle, by testing fragmented arrays of equal-length opaque surfaces at different distances (Distance Only), connected by transparent surfaces to create an enclosure, and different-length surfaces at equal distances (Length Only) . Furthermore, to distinguish between the ability to use distances between any objects, to perform amodal completion, or to specifically use extended surfaces we also tested a rectangular array of fragmented corners (Corners Only), following studies of human children 3