Have you ever remembered something happening to you, only to realise later that you have unknowingly invented the experience yourself? This is called “false memory”, and it’s a widespread phenomenon. We as humans are incredibly susceptible to suggestion. Our experiences and surroundings have an uncanny ability to shape our memories, and we find ourselves “remembering” things which never really happened to us.
A new study published from Queen Mary University has demonstrated that false memory might not be exclusive to humans, using a familiar creature: the buff tailed bumblebee (Bombus terrestris). This wonderful little bumblebee is common throughout Europe, and like other bees depends on pollen and nectar to keep itself, and its colony fed.
The expression “busy as a bee” is on point. Bees travel huge distances to gather ridiculous amounts of pollen and nectar. It’s a lot of work, requiring multiple trips from the nest to flowers. Buff tailed bees are known to forage kilometres from their home. To minimise the amount of energy a bumblebee expends, it must concentrate on the most rewarding areas: patches with high floral density, and then selecting the species which provide the greatest reward.
But how does a bumblebee remember which flower contains the greatest reward? It uses a combination of different stimuli. By associating the colour, shape, pattern and smell of the flower with the reward it provides – bumblebees are able to optimise their foraging efficiency.
But when you’re a fuzzy little bee, in a big scary world – not every day is meant for foraging. Bees are unable to fly in high winds, and heavy rain. They must wait for the inclement weather to pass before continuing to search for food. Sometimes this means days without visiting flowers, while the colony begins to deplete their stores. Once the sun comes out and the wind dies downw, the bees head out to forage again – and using their little brains (which are no bigger than a grain of rice) can remember exactly which flowers are the right flowers to visit. Or so we once thought.
In a new study published in the Journal of Current Biology, researchers trained bees to feed on artificial flowers containing a nectar award. Some bees initially fed on flowers which were a solid yellow, and then switched over to a black-and-white boldly patterned flower. Other bees were given the opposite conditioning, feeding first on flowers with a bold black-and-white pattern, before moving onto uniformly yellow flowers.
Bees were then presented with a choice of flowers: a solid yellow, a bold black and white pattern, (as seen before), or a totally novel bold yellow pattern. Immediately following the conditioning, bees remembered the most recent reward, and preferentially visited the last flower which had given them a nectar reward. Bees which had fed most recent on the black-and-white patterned flowers, continued to choose the black-and-white patterned flowers one day and three days after being conditioned. However, bees which most recently fed on the solid yellow flowers made a peculiar choice – opting more frequently for the yellow targeted flower (a completely novel selection) despite having two options which had previously demonstrated to provide a perfectly adequate reward.
This strange behaviour is similar to the erroneous way in which we remember events through false memory. Perhaps recognising commonality might be a beneficial response in novel situations, however making new decisions when two perfectly valid and vetted options are available could be a terribly costly decision for a bee. To put things in a human perspective, imagine you’ve misplaced your last piece of chewing gum. You are pretty sure that you might have eaten it, but it also might have given it to a friend to hold. Accusing your friend of eating your gum, or prying open your friend’s mouth to have a look might not be the best solution, and might cause a cost to your friendship.
Hunt, K. L., & Chittka, L. 2015. Merging of Long-Term Memories in an Insect. Current Biology, 1–5. doi:10.1016/j.cub.2015.01.023