Lab mice are getting their own back by deliberately messing up experiments

Laboratory mice are deliberately making mistakes during experiments and annoying the scientists watching them. 

The humble lab mouse has been used in tests for hundreds of years, but it seems like the small rodents have been carrying out their own experiments, as they do not always perform as expected. 

Now it seems this isn't just scientific anomaly, but a concerted effort by the mice to mess things up.

Dr Kishore Kuchibhotla, an assistant professor at Johns Hopkins University, told the Times: 'It can be quite frustrating. You'll be doing an experiment and the [mice] just don't seem to be getting it. You've done everything correctly but they still seem to be making lots of errors.'

The researchers thought the mice were either becoming stressed, or they were deliberately trying to understand their environment and were testing their own knowledge. 

Dr Kuchibhotla and his colleague Ziyi Zhu, a graduate neuroscience student, decided to test this theory.

They created an experiment where thirsty mice could hear one of two sounds. When one sound was played, they were supposed to turn a wheel to the left using their front legs, and for the other sound, they had to turn the wheel to the right. 

When the mice did this correctly, they were rewarded with a drink of water, and when they spun the wheel the wrong way, they were given nothing at all. 

The researchers tracked mouse choice, response speed and accuracy, and noticed that over time the mice got better at the task, but at points, the mice would stop following the rules, and do things like spin the wheel in one direction, no matter what sound they heard. 

The researchers then stopped rewarding the mice for their correct answers, and soon the rodents began responding to the sounds more accurately. 

The researchers believed the mice knew what they were doing the whole time, and were purposefully giving up the reward to explore their environment by doing experiments of their own.

'We find that when the animal is exploring, they engage in a really simple strategy, which is, "I'm going to go left for a while, figure things out, and then I'm going to switch and go right for a while",' said Dr Kuchibhotla said. 'Mice are more strategic than some might believe.'

Mr Zhu added: 'Errors during animal learning are often considered as mistakes. Our work brings new insight that not all errors are the same.'

During the experiments, Dr Kuchibhotla said he became 'a little bit of a mouse psychologist' to interpret their behavior. Like working with a nonverbal infant, he and Mr Zhu had to guess the underlying mental processes from the behaviour alone.

'That's what was really fun in this project, trying to figure out what the mouse is thinking,' he said.

'You have to think about it from the perspective of the animal.'

The findings were published in the journal Current Biology. 

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