Although once thought to be absolute proof, eyewitness testimony has been found to be one of the least reliable forms of evidence. It is not that most people deliberately lie, but memories can be faulty. People can forget things or misremember them. People can think they’ve seen things that they haven’t, misidentify others who were there, remember things in the wrong order or simply be completely wrong about what they saw, while still deeply believing that they are telling the truth.

While this phenomenon has been widely studied in humans, a new study on bumblebees published in the journal Current Biology is the first to explore false memories in non-human animals. The researchers involved now believe that bad memories could be widespread in the animal kingdom.

“We discovered that the memory traces for two stimuli can merge, such that features acquired in distinct bouts of training are combined in the animal’s mind,” sais Lars Chittka of Queen Mary University of London in a statement.

According to Chittka, because of this merging, “stimuli that have actually never been viewed before, but are a combination of the features presented in training, are chosen during memory recall.”

Chittka has been working with bumblebees for 20 years and has discovered that they are generally clever animals. They have shown an ability to remember the colors, scents and patterns of different flowers and the ability to navigate to certain chosen flowers and home again even over long distances.

In most testing of animal memory, errors have been taken to mean that the animal failed to learn or learned and forgot. Chittka and his colleague Kathryn Hunt wondered if, instead, lapses might reflect a more human type of memory failure.

The researchers trained the bees to expect a reward when visiting a particular solid yellow flower, then another black and white flower or vice versa. In testing following the training the animals were presented with three flowers. A flower with yellow and white stripes was added to the yellow and black-and-white striped flower that had been used for the training.

Immediately following the training the bumblebees demonstrated good short term memory by returning to the flower that they had most recently received a reward from.

During a second round of testing one to three days after the training, the bees initially showed the preference taught by their training, but later in the day they appeared to become confused. About half the time the bees selected the yellow-and-white flower, even though it was not part of their training.

According to the researchers the observed merging of long term memories is similar to the “memory conjunction” errors sometimes made by humans. Chittka and Hunt believe that the lapse is a side effect of an adaptive memory working well. Chitka’s team, in fact, has previously found that people who are good at learning rules for classifying objects are more prone to these types of errors than others.

“There is no question that the ability to extract patterns and commonalities between different events in our environment [is] adaptive. Indeed, the ability to memorize the overarching principles of a number of different events might help us respond in new situations. But these abilities might come at the expense of remembering every detail correctly,” said Chittka.

Given the limited brain capacity of bees, a tendency to economize by storing classes of objects rather than individual ones would be strong.

The researchers are now using radar to follow bees over a lifetime to observe their choice of flowers.

“We are fascinated to learn how lifetime experiences accumulate and are integrated in making day-to-day foraging decisions,” Chittka said.