Researchers at the University of Sheffield have discovered that honeybees are able to solve a type of maths test using visual, non-numeric cues.
Previous research identified that many animal species demonstrate numerical cognition. However, it has been difficult to determine whether the species in question were using a sense of number to solve the tasks or using other cues. Some studies have been able to control for at least one non-numerical cue when investigating numerical cognition. However, this new piece of research uses methods that are able to assess multiple non-numerical continuous cues.
Two groups of honeybees were trained to distinguish between placards with greater or fewer shapes by finding a sugar solution reward on the placards with multiple shapes, and an aversive solution on those with fewer shapes. To test whether the training had been successful, the bees completed an unrewarded learning test, showing high performance. This proved that the bees had some kind of numerical cognition – however, it did not answer how the bees were able to complete the task.
Continuous non-numerical cues include the area, size, and shape of elements, amongst others. To determine if the bees used non-numerical cues, the same honeybees were subjected to another unrewarded test where the placards contained the same number of elements but varied in edge length and spatial frequency. If the honeybees were using numerosity, both groups should have preferred all of the placards equally. However, the honeybees were selective in their choice of preferred placard. The honeybees trained to recognise more elements chose placards with a higher level of continuous variables, and those trained to recognise fewer elements chose placards with a lower level, both ignoring numbers. These results suggest that honey bees respond to continuous cues over the number of elements.
Further innovative tests where both the number of elements and level of continuous variables differed between cards have confirmed that the bees were not using numerosity. Bees trained to recognise more elements preferred the placards with high levels of continuous variables but fewer elements. Bees trained to recognise fewer elements preferred the placards with low levels of continuous variables but more elements.
The results demonstrate that honeybees use continuous cues to discriminate between different placards containing varying numbers of shapes, not numerosity. This new finding may also be applicable to other numerical cognition studies involving honeybees and other animals.
Dr HaDi MaBouDi, an author of the paper from the Department of Computer Science at the University of Sheffield said: “This doesn’t mean that bees or other non-verbal animals can’t understand numbers, but it does suggest that animals use non-numeric properties to solve the math problems they often face if such information is available. However, we hope that our study provides insight into better methods of exploring mathematical cognition in animals.”
