Local-feature assembling in visual pattern recognition and generalization in honeybees

Generalization is a cognitive ability that allows similar stimuli along a given dimension to be treated as equivalents(1-3). Insects exhibit high levels of visual generalization(4-6). Honeybees trained to recognize complex visual stimuli on the basis of a single feature generalize their choice to novel stimuli sharing that common feature with the trained stimuli(7). The demonstration of this kind of performance has been limited to the use of a single visual feature, and the possibility that bees link different features in learning a visual pattern has been denied(8,9). Here we show that honeybees trained with a series of complex patterns sharing a common layout comprising four edge orientations remember these orientations simultaneously in their appropriate positions, and generalize their response to novel stimuli that preserve the trained layout. Honeybees also generalize their response to patterns with fewer correct orientations, depending on their match with the trained layout. Stimulation of the achromatic L-photoreceptor input is necessary for this task. The mini-brain of the honeybee can thus extract regularities in its environment and establish correspondences among correlated features. It can thus generate a large set of object descriptions from a finite set of elements.