When the mouse stands in front of the mirror, does it know that it sees itself? Scientists have discovered this, and their experiments have revealed that this is a very complex story.
Because yes, rats can pass the classic mirror test (see box) successfully, but only if a number of strict conditions are met. This can be read in the magazine nervous cells.
Classic mirror test
To determine whether animals recognize themselves in a mirror and are therefore self-aware, what researchers often call the “classic mirror test.” This involves sticking a sticker or placing a spot on a part of the body that is impossible for the animal to see without the aid of a mirror. The researchers then place the animal in front of a mirror and see if it makes any attempts to remove the sticker or stain. When an animal does this, it is a strong indicator that it recognizes itself in the mirror.
For the new research, scientists collected a number of black mice. They put a dab of white ink on the mice’s foreheads and then placed them in front of a mirror. Then the mice started rubbing their foreheads; A sign that they recognized themselves. But – and now it gets interesting – the mice only did this if they had previously stood in front of a mirror, had been in contact with mice that looked like them and if the inkblot was reasonably large.
The ink spot is very small
The researchers came to this conclusion after placing mice with small ink spots (about 0.2 square centimeters) on their foreheads in front of a mirror. These mice did not rub more vigorously to clean their foreheads. “Mice need important external sensory cues to pass the mirror test,” said researcher John Yukos. “We have to put a lot of ink on their heads, and because they feel this ink, they are somehow able to detect this ink on their heads – through their reflection.”
Very little experience
The researchers also conducted experiments on mice that had never seen a mirror before. An ink blot was placed on the foreheads of these mice, and they were then placed in front of a mirror. But these mice did not rub their foreheads. He points out that some experience with the mirror is needed; Without it, your mouse doesn’t pass the classic mirror test.
Because previous studies – with chimpanzees – suggested that social experiences are also required for mirror-image recognition, the researchers conducted another experiment. This time with mice that lived in social isolation. An ink blot was placed on the foreheads of these mice, and they were then placed in front of a mirror. As expected, these mice did not clean their foreheads either. The same is true for black mice, who have only seen white mice during their lives and thus have never laid eyes on a specific person who looks like them. She suggests that mice need social experiences with peers who are similar to them to develop the neural networks underlying self-recognition.
Strictly speaking, after this research you can conclude that rats – under certain conditions – are able to pass the mirror test. Since the classic mirror test is designed to determine whether animals are self-aware, you might think this also proves that rats are self-aware. But researchers don’t want to go that far. This is of course partly because several conditions must be met for a mouse to exhibit behavior that indicates that it recognizes its reflection. According to the researchers, the experiments only show that mice – under certain conditions – are able to detect a change in their appearance. But this does not necessarily mean that they are self-aware.
However, researchers aren’t done with mice yet. For example, in the future they want to know whether mice can notice external change – even if they can’t feel it. As mentioned earlier, the mice felt the large ink blots and this may have helped the mice to later detect the ink through their mirror image. But suppose they do not feel the external change, can they also notice it through their reflection in the mirror? To find out, the researchers are considering using a technique that is also widely used on social media, where people help themselves get a dog nose or rabbit ears with the help of filters. In a similar way, the researchers were also able to modify the mice’s appearance – without them feeling anything – before placing them in front of the mirror again. The researchers also want to check what exactly happens in the mice’s brains when they stand in front of a mirror.
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