Mirror Test: Which Animals Are Able to Recognize Their Own Reflection?

Elephant art has captured attention for years. While trainers teach elephants how to grip a paintbrush with their trunks and create strokes on a canvas, the elephants are largely left to express themselves in their own unique styles, as explained by Alex Melamid, founder of the elephant art academy [source: Bukowski].

Does this form of art suggest that elephants possess a level of self-expression that could indicate humanlike consciousness? And what about their self-awareness or self-recognition? One method for exploring animal cognition is mirror testing.

What Is the Mirror Test?

The mirror self-recognition (MSR) or mark test is a well-known experiment where a colored mark is placed on an animal, and its reflection in a mirror is shown. The animal’s response is observed to determine if it recognizes the mark as belonging to itself.

If the animal attempts to remove the colored mark from its body, the mirror test indicates that it recognizes its own reflection.

The Mirror Test and Animal Cognition

Many individuals have no difficulty in intuitively believing that other large-brained mammals (and even their smaller-brained companions, such as beloved pets) show signs of consciousness.

However, when it comes to non-mammalian creatures like fish, insects, and worms, these same individuals often hesitate to consider whether these species also display any form of consciousness.

Some argue that self-recognition is a key indicator of self-awareness. Self-awareness is a state that can reflect introspection, personal identity, and consciousness at levels similar to that of humans.

In human development, it is often believed that children become self-aware once they gain the cognitive ability to recognize their own reflection in a mirror. Children typically achieve this milestone around 18 months of age.

Early research showed that, like humans, some members of the great ape family are capable of recognizing their own reflections in mirrors. For many years, it was believed that this was the extent of self-recognition. However, when the classic mirror test was modified to suit the specific traits of dolphins and elephants, it was discovered that they too demonstrate signs of self-recognition.

For dolphins, researchers designed a test to observe their interest in a mark without using hand gestures. In the case of elephants, their response was studied when large mirrors, allowing them to view their entire bodies, were placed in their living areas.

Perhaps even more surprisingly, due to the significant evolutionary gap, some species of birds and fish have developed the ability to recognize themselves. A 2008 study revealed that magpies also attempt to investigate unfamiliar marks placed under their beaks when presented with a mirror.

In 2019, the cleaner fish (Labroides dimidiatus) passed a modified mark test. This small fish displayed a scraping behavior when it saw a colored tag on its body in the mirror [source: Kohda]. This discovery raised questions about whether self-recognition, as tested in the mirror test, truly reflects self-consciousness.

Nonhuman Animals That Pass the Mirror Test

A 2023 review of 50 years of animal self-recognition studies found that, to date, only social animals demonstrate self-recognition [source: Lei].

These animals have successfully passed the mirror test in at least two independent studies without prior training:

The following animals have passed the mirror test just once or yielded controversial results:

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