In a study published this month in the journal Science, a team of researchers from Queen Mary University of London and Macquarie University found that bumblebees could identify objects by shape in the dark if they had seen, but not touched, them in the light, and vice versa, demonstrating a clear ability to transmit recognition across different senses.
Solvi et al demonstrated that bumblebees possess the ability to integrate sensory information in a way that requires modality-independent internal representations. Image credit: Lars Chittka.
Cross-modal recognition is the ability to recognize objects across different senses.
For example, humans can easily recognize something they’ve previously seen through touch alone.
Outside of our species, cross-modal object recognition has been shown only in primates, rats, dolphins and one species of fish.
Whether it is widespread throughout the animal kingdom, however, has been debated.
Because bumblebees are known to be able to forage in both light and dark conditions, they are ideal creatures to examine to understand if the small brains of invertebrates are capable of cross-modal recognition across vision and touch.
“We’ve long known that bees can remember the shapes of flowers. But a smartphone can recognize your face, for example, and does so without any form of awareness,” said senior author Professor Lars Chittka, a researcher at Queen Mary University of London.
“Our new work indicates that something is going on inside the mind of bees that is wholly different from a machine — that bees can conjure up mental images of shapes.”
In the light, but barred from touching the objects, bumblebees were trained to find rewarding sugar water in one type of object (cubes or spheres) and bitter quinine solution in the other shape.
When tested in the dark, the bees preferred the object that was previously rewarding, spending more time exploring them.
The insects also solved the task the other way around. After they learned to find a particular shape in the dark, they were tested in the light and again preferred the shape they had learned was rewarding by touch alone.
“The results of our study show that bumblebees don’t process their senses as separate channels — they come together as some sort of unified representation,” said lead author Dr. Cwyn Solvi, a scientist at Macquarie University.
“This is an amazing feat when you consider the miniscule size of a bee’s brain,” said co-author Selene Gutierrez Al-Khudhairy, a Ph.D. student at the University of York.
“Future investigations of the neural circuitry underlying this ability in bees may one day help reveal how our own brains imagine the world as we do.”
“This doesn’t mean bees experience the world the same way we do, but it does show there is more going on in their heads than we have ever given them credit for,” Dr. Solvi said.
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Cwyn Solvi et al. 2020. Bumble bees display cross-modal object recognition between visual and tactile senses. Science 367 (6480): 910-912; doi: 10.1126/science.aay8064
