Humans are one of very few animals known to be able to recognise objects across senses.

Key points: Bumblebees were able to recognise objects by sight that they'd only previously felt

Bumblebees were able to recognise objects by sight that they'd only previously felt Scientists think cross-modal recognition requires some sort of mental imagery

Scientists think cross-modal recognition requires some sort of mental imagery Creating mental imagery is considered a 'building block' of consciousness

For instance, if we know what a jar of honey looks like we could probably find it by touch alone from the top shelf of the pantry.

Scientists think this ability — called cross-modal object recognition — exists at least partly because we are able to imagine the object in our brain, a skill that is a "building block" of consciousness.

But now a team of scientists believe they have evidence bumblebees can also create mental imagery, they report in the journal Science.

The tiny insects are able to recognise objects by sight that they've only previously felt, and vice versa, according to study co-author Cwyn Solvi from the Queen Mary University of London (QMUL) and Macquarie University.

"Many have thought that bees' small brains simply react to stimuli and output motor behaviours without any internal representations of the world," Dr Solvi said.

In humans, the ability to solve a cross-modal recognition task, like those the bumblebees solved, requires mental imagery."

The question now is whether we have underestimated the intelligence of bees, or overestimated how complex a brain needs to be to perform cross-modal recognition.

The brain power of bees

The researchers had previously found that bees can learn by watching other bees, and can show positive emotional states, but even they were impressed by this latest feat.

"We already knew that bees were pretty clever. But nonetheless, our new results surprised even us," Dr Solvi said.

Other research led by Adrian Dyer from RMIT, who was not involved in the latest study, has shown that bees are capable of recognising human faces and doing basic calculations.

"Two-plus-three may seem trivial, but it's the 'plus' that takes memory," Dr Dyer said.

How do you "train" a bee?

The researchers separated bumblebees into groups and "trained" them to recognise that either spheres or cubes contained a sweet sugar water.

They trained some in darkness, where they put the sugar water either into spheres or cubes, and a bitter quinine solution into the other.

The bees were only able to feel the shapes in this situation, and learnt to associate the specific shape with the reward.

Bees were trained in the dark to recognise rewarding shapes based on feel alone. ( Supplied: Amelia Kowalewska & Joann Brebner )

They trained others in the light, but in that case the bees could only see the shapes but not touch them, and leant to recognise the rewarding shape visually.

They then swapped them around, so that the bees trained in the light without touching the objects had to feel out the rewarding sugar water filled shape from the one with the quinine solution in total darkness, and vice versa.

In their new environment, the bees spent significantly more time with the object they learnt was previously rewarding, despite in the case of half the bees having never seen the object, and the other half having never touched it.

Is this proof of 'consciousness' in bees?

While we need to be careful with terms like "consciousness", this is evidence that we share a bit more in common with bumblebees than previously known, according to co-author Lars Chittka from QMUL.

"This does not mean that it is a formal proof of consciousness — a notoriously elusive phenomenon for which neither philosophers nor scientists have come up with a simple set of criteria," Professor Chittka said.

"Nonetheless, the new finding together with other work on the psychology of bees, nudges the probabilities in the direction of there being conscious awareness in these creatures."

Being capable of producing mental imagery, and being able to think about objects in the abstract, can provide animals with some advantages too.

"A conscious animal can use its mind to explore new solutions to unexpected challenges," Professor Chittka said.

But the potential to have a level of conscious thought also raises ethical questions for us.

"[It] provides added reasons for their urgent conservation," he said.

"We shouldn't just protect bees because we need them as pollinators of our crops, but also because they deserve our respect as individuals with an awareness of the world around them, including the often unfavourable environments to which we humans expose them."