Pattern recognition in bees: size of regions in spatial layout

Abstract

These experiments investigate the relation between the local features that are known to be discriminated by bees and the size of local regions in the spatial layout that is assumed to be the essence of pattern discrimination. Previous work with the Y-choice apparatus demonstrates that bees discriminate very well from a distance the angle of inclination of black-white edges of bars and striped patterns, but that the performance is progressively reduced by increasing the variety of contrasting edges in the pattern or its background. We devised a series of tests which show that bees can discriminate different black-white striped patterns on the basis of the spatial layout of different angles of stripes. The patterns were round discs divided into two, four or eight sections that were filled with stripes at different angles. With discs divided into two or four sections, the bees could discriminate between left-right mirror images and more effectively between top-bottom mirror images, but performed best when they discriminated between a pattern and itself rotated by 180°. Patterns with orthogonal stripes appear to be more difficult than the others, and discs divided into eight segments are too difficult unless some gross features are outstanding. The results are consistent with the view that the average angles of inclination are discriminated in local regions, and that the bee sees the gross spatial layout especially in the lower half of the pattern. The area required for resolution of spatial layout with this stimulus is about four stripe periods, but discrimination between vertical and horizontal can be done with a single edge.