Mice Show Self-Recognition in Mirror Test

Mice have passed the mirror test, demonstrating the ability to recognize themselves in a mirror reflection. The study, published in the journal Neuron, marks the first time mice have shown mirror-induced self-directed behavior, joining humans, great apes, some monkeys, dolphins, and elephants. Researchers marked the foreheads of dark-furred mice with white ink and observed that the mice groomed themselves in front of the mirror to remove the ink. The mice did not exhibit self-grooming behavior when the ink was a smaller blotch or when it was swapped for black ink. The study also identified specific neurons in the mice's ventral hippocampus that were activated during self-recognition. The researchers hope to further investigate the mice's ability to self-recognize without tactile stimuli and understand how they distinguish themselves from other animals.