Seven experiments on pattern vision of the honeybee, with a model

When vertically presented patterns are fixed in relation to the point of choice of the bees, the locations of areas of colour or black can be discriminated in the vertical direction, and in the horizontal direction when the bees use some mark with green contrast on which to stabilize. The bees can fixate on a radial pattern, a spot, or a ring of spots. Resolution depends on fixation, which depends on green contrast, but the discrimination of locations then depends on the photon flux at green and blue receptors. The model proposes that, when the eye is stabilised, a tonic channel from all receptor types is activated in the region of the eye that looks at the cue. This channel generates a perceptual space in which location, colour and size contribute to a signature for each cue in each eye. In other channels of processing, the stimulus is the phasic modulation of green receptors by edges, and these pathways are colour blind. When the patterns are composed of bars, the cues are the radial and tangential edges and the integrated edge orientation, irrespective of shuffling of locations on the target. Orientation can be detected in fuzzy edges with a gradient of black to white over about 60°subtended from the point of choice. These cues correspond to the response profiles of large-field, phasic, coarsely tuned filters. There is no evidence that cues from edges have a spatial tag. The model also proposes that each filter for average orientation, or radial or tangential edges, corresponds to an ascending succession of phasic neurones. Each processing channel generates a perceptual space where combinations of related cues form signatures, and at least one signature is passed to memory as an index item. A pattern may generate several signatures but patterns are discriminated only when their signatures differ. In the bee there is no evidence for the re-assembly of the pattern. Copyright (C) 2000 Elsevier Science Ltd.