Miniature Brains of Bees and Wasps Recognize Faces

Humans have a remarkable ability to detect and visually identify conspecifics on the basis of their faces, which is a crucial capacity in social interactions. A new study shows that two insect species with relatively small brains of less than a million neurons — the honeybee (Apis mellifera) and the European wasp (Vespula vulgaris) — use visual processing mechanisms that are similar to humans’.


The study was conducted by Dr. Adrian Dyer of Monash University and the Royal Melbourne Institute of Technology and his colleagues from the Johannes Gutenberg Universität Mainz and the Universities of Toulouse and Cologne.

“The expertise of humans for recognizing faces is largely based on holistic processing mechanism, a sophisticated cognitive process that develops with visual experience,” the researchers said.

“The various visual features of a face are thus glued together and treated by the brain as a unique stimulus, facilitating robust recognition.”

“Holistic processing is known to facilitate fine discrimination of highly similar visual stimuli, and involves specialized brain areas in humans and other primates.”

“Although holistic processing is most typically employed with face stimuli, subjects can also learn to apply similar image analysis mechanisms when gaining expertise in discriminating novel visual objects, like becoming experts in recognizing birds or cars.”

“In our study, we ask if holistic processing with expertise might be a mechanism employed by the comparatively miniature brains of insects.”

Dr. Dyer and co-authors tested whether honeybees and European wasps can use holistic-like processing with experience to recognize images of human faces.

“Two very useful tests already exist for establishing that human subjects use holistic face processing: these are the part-whole effect, and the composite-face effect,” they explained.

“The part-whole effect reveals that when face features like eyes, nose or mouth are perceived in isolation, it’s harder to recognize a face compared to when these features are viewed in the context of a full face.”

“The composite-face effect refers to the large drop in performance accuracy when correct inner face features are viewed in the context of incorrect outer features.”

“In human processing of familiar faces, the different elemental features are glued together into a gestalt to enable improved face recognition accuracy.”

When the team used these principles to test the insects, both species were able to learn achromatic images of human faces.

“Both species could learn similar faces from a standard face recognition test used for humans, and their performance in transfer tests was consistent with holistic processing as defined for studies on humans,” the study authors said.

“Tests with parameterized stimuli also revealed a capacity of honeybees, but not wasps, to process complex visual information in a holistic way, suggesting that such sophisticated visual processing may be far more spread within the animal kingdom than previously thought, although may depend on ecological constraints.”

The study was published in the journal Frontiers in Psychology.

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Aurore Avarguès-Weber et al. Does Holistic Processing Require a Large Brain? Insights from Honeybees and Wasps in Fine Visual Recognition Tasks. Front. Psychol, published online July 31, 2018; doi: 10.3389/fpsyg.2018.01313

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