While humans commonly examine their reflections, recognizing oneself in mirrors extends to various species. Initiated with chimpanzees in 1970, mirror recognition trials involved creatures from ants to manta rays.

Some, like primates, dolphins, elephants, magpies, and manta rays, exhibit self-awareness, while debates persist on the test's reliability. The mirror test underscores the significance of appreciating diverse life forms, and fostering respect regardless of differences.

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(Photo : DOMINIQUE FAGET/AFP via Getty Images)
This photo taken on December 16, 2016 shows a macaques monkey looking into the mirror of a motorbike in the grounds of a temple in Jaipur in the Indian state of Rajasthan.

Animals That Passed the Mirror Test

The Mirror Self-Recognition Test (MSR) assesses self-awareness by marking an animal's unseen body part, like the head or shoulder, with a colored, odorless mark. Passing involves the animal spontaneously rubbing the mark upon seeing itself in the mirror, demonstrating an understanding of "self" versus "other."

During the mirror test, scientists mark an animal's body and observe its reaction in front of a mirror. Passing animals typically adjust their positions to inspect the new mark, showing attention to the marked body part. Even if they don't pass, animals may react aggressively or affectionately, possibly mistaking their reflection for another of their kind.

Currently, nine non-human species, including mammals, fish, and primates like chimpanzees, orangutans, dolphins, killer whales, elephants, European magpies, manta rays, and horses, have passed the mirror test.

Frans de Waal, a primatologist, emphasizes the need for spontaneous self-inspection without training or rewards. Capuchin monkeys, tested by de Waal, failed to meet these criteria. Some amusing reactions may occur, highlighting the diverse responses animals have to their reflections.

While the mirror test provides insights into self-awareness, the absence of success in certain species doesn't imply a lack of consciousness. Ongoing research is crucial to comprehensively understand animal cognition.

READ ALSO: Fish With Self-Awareness? Bluestreak Cleaner Wrasse Show Recognition Signs of Their Own Faces in Photos

Testing Non-Human Primates on the Mirror Test

During the chimpanzee experiments in 1970, four chimpanzees were rendered unconscious and had red dye applied to their faces. Upon awakening, they examined the marked areas in the mirror, demonstrating an understanding that they were seeing themselves. This mark test is now regarded as conclusive proof of mirror self-awareness, with other great apes like orangutans also passing the examination.

While bonobos were observed inspecting unseen body areas using a mirror in a 1994 study, results for gorillas have been inconclusive. Monkeys typically perceive their reflections as other animals, but a 2017 study led by neurobiologist Mu-Ming Poo and his colleagues trained three young male rhesus monkeys to recognize themselves in a mirror.

The intensive training involved flashing a red laser pointer randomly, rewarding the monkeys when they touched the dot. After several weeks of training, the monkeys passed the classic MSR test, showing self-recognition behaviors, suggesting shared mental processes across primates.

The study implies that primates share underlying mental processes for the mirror test, but monkeys may need more information to pass it. However, critics argue that spontaneous, self-directed behaviors, essential for the MSR test, were lacking in the untrained monkeys, challenging the validity of the test.

Poo and colleagues plan to investigate brain circuit changes during mirror training and encourage new tests for self-recognition in different species.

RELATED ARTICLE: Penguins Added to the List of Self-Aware Animals After Passing the Mirror Test

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