Demonstrating an unprecedented degree of cognitive complexity in an insect, researchers report that bumblebees are capable of recognizing objects across senses. While cross-modal object recognition was previously thought to be a highly complex cognitive capacity capable by few animals outside humans, the results suggest that the bumblebee - with a brain with fewer than one million neurons - can create mental images of objects using information from multiple senses and form sophisticated mental representations of their surrounding world. "This is a remarkable finding, showing that these little invertebrates with very different brain structures to vertebrates are capable of experiencing an object with one sensory modality and later recognizing it with another," write Gerhard von der Emde and Theresa Burt de Perera in a related Perspective. Cross-modal recognition is the ability to recognize objects across different senses. Humans, for example, can easily recognize something they've previously seen through touch alone, for example when they find a set of keys by fishing around sightlessly at the bottom of a backpack. Outside of humans, cross-modal object recognition has been shown only in primates, rats dolphins and a single species of fish. Whether it is widespread throughout the animal kingdom, however, has been debated. According to Cwyn Perry and colleagues, 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. In their experiment, Perry et al. trained bumblebees to differentiate two differently shaped objects - cubes and spheres, and using only touch or vision - and tested to see if they could identify the same objects using only the other sense. The authors discovered that the bees were able to successfully recognize the objects cross-modally in both directions; sight-to-touch and touch-to-sight.
