Bees can experience false memories, scientists say

What do bees and Brian Williams have in common?

Turns out, they are both prone to "conflating" their memories.

It has long been known that humans – even those of us who aren't famous news anchors – tend to recall events that did not actually occur. The same is likely true for mice: In 2013, scientists at MIT induced false memories of trauma in mice, and the following year, they used light to manipulate mice brains to turn painful memories into pleasant ones.

Now, researchers at Queen Mary University of London have shown for the first time that insects, too, can create false memories. Using a classic Pavlovian experiment, co-authors Kathryn Hunt and Lars Chittka determined that bumblebees sometimes combine the details of past memories to form new ones. Their findings were published today in Current Biology.

“I suspect the phenomenon may be widespread in the animal kingdom," Dr. Chittka said in a written statement to the Monitor.

First, Chittka and Dr. Hunt trained their buzzing subjects to expect a reward if they visited two artificial flowers – one solid yellow, the other with black-and-white rings. The order didn’t matter, so long as the bee visited both flowers. In later tests, they would present a choice of the original two flower types, plus one new one. The third type was a combination of the first two, featuring yellow-and-white rings. At first, the bees consistently selected the original two flowers, the ones that offered a reward.

But a good night’s sleep seemed to change all that. One to three days after training, the bees became confused and started incorrectly choosing the yellow-and-white flower (up to fifty percent of the time). They seemed to associate that pattern with a reward, despite having never actually seen it before. In other words, the bumblebees combined the memories of two previous stimuli to generate a new, false memory.

“Bees might, on occasion, form merged memories of flower patterns visited in the past,” Chittka said. “Should a bee unexpectedly encounter real flowers that match these false memories, they might experience a kind of deja-vu and visit these flowers expecting a rich reward.”

Bees have a rather limited brain capacity, Chittka says, so it’s probably useful for them to “economize” by storing generalized memories instead of minute details.

“In bees, for example, the ability to learn more than one flower type is certainly useful,” Chittka said, “as is the ability to extract commonalities of multiple flower patterns. But this very ability might come at the cost of bees merging memories from multiple sequential experiences.”

Chittka has studied memory in bumblebees for two decades. Bees can be raised and kept in a lab setting, so they make excellent long-term test subjects.

“They are [also] exceptionally clever animals that can memorize the colors, patterns, and scents of multiple flower species – as well as navigate efficiently over long distances,” Chittka said.

In past studies, it was assumed that animals that failed to perform learned tasks had either forgotten them or hadn’t really learned them in the first place. Chittka’s research seems to show that animal memory mechanisms are much more elaborate – at least when it comes to bumblebees.

“I think we need to move beyond understanding animal memory as either storing or not storing stimuli or episodes,” Chittka said. “The contents of memory are dynamic. It is clear from studies on human memory that they do not just fade over time, but can also change and integrate with other memories to form new information. The same is likely to be the case in many animals.”

Chittka hopes this study will lead to a greater biological understanding of false memories – in animals and humans alike. He says that false memories aren’t really a “bug in the system,” but a side effect of complex brains that strive to learn the big picture and to prepare for new experiences.

“Errors in human memory range from misremembering minor details of events to generating illusory memories of entire episodes,” Chittka said. “These inaccuracies have wide-ranging implications in crime witness accounts and in the courtroom, but I believe that – like the quirks of information processing that occur in well known optical illusions – they really are the byproduct of otherwise adaptive processes.”

“The ability to memorize the overarching principles of a number of different events might help us respond in previously un-encountered situations,” Chittka added. “But these abilities might come at the expense of remembering every detail correctly.”

So, if generating false memories goes hand in hand with having a nervous system, does all this leave Brian Williams off the hook?

“It is possible that he conflated the memories,” Chittka said, “depending on his individual vulnerability to witnessing a traumatic event, plus a possible susceptibility to false memories – there is substantial inter-person variation with respect to this. It is equally possible that he was just ‘showing off’ when reporting the incident, and is now resorting to a simple lie to try to escape embarrassment. That is impossible for me to diagnose.”

But if Mr. Williams genuinely did misremember his would-be brush with death, Chittka says he shouldn’t be vilified.

“You cannot morally condemn someone for reporting something they think really did happen to them,” Chittka said. “You cannot blame an Alzheimer patient for forgetting to blow out the candle, even if they burn down the house as a result. In the same way, you can't blame someone who misremembers a crime as a result of false memory processes."