Vision of the honeybee Apis mellifera for patterns with one pair of equal orthogonal bars

The visual discrimination of patterns of two equal orthogonal black bars by honeybees has been studied in a Y-choice apparatus with the patterns presented vertically at a fixed range. Previous work shows that bees can discriminate the locations of one, or possibly more, contrasts in targets that are in the same position throughout the training. Therefore, in critical experiments, the locations of areas of black were regularly shuffled to make them useless as cues. The bees discriminate consistent radial and tangential cues irrespective of their location on the target during learning and testing. Orientation cues, to be discriminated, must be presented on corresponding sides of the two targets. When orientation, radial and tangential cues are omitted or made useless by alternating them, discrimination is impossible, although the patterns may look quite different to us. The shape or the layout of local cues is not re-assembled from the locations of the bars, even when there are only two bars in the pattern, as if the bees cannot locate the individual bars within the large spatial fields of their global filters.