Consciousness: How animals see themselves

How different animals demonstrate self-awareness and sentience

18 months
Bluestreak cleaner wrasse

Are animals self-aware?

Perhaps the biggest question in animal intelligence, and the one which is hardest to empirically prove, is whether any non-human species are conscious.

Consciousness is a difficult concept to define, but it is generally seen as a state of self-awareness. Related concepts include metacognition: not just to think, but to know we are doing it.

Scientists barely understand how consciousness works in humans, let alone in other species. But in 2012, a group of leading psychologists signed the Cambridge Declaration on Consciousness.

This declaration asserted that “humans are not unique in possessing the neurological substrates that generate consciousness”. In other words, some animal species are considered self-aware.

The mirror test

The mirror test, developed by psychologist Gordon Gallup in the 1970s, is the most popular way to measure self-awareness in animals.

This test involves placing a mark on an animal, like a sticker or a spot of paint. Afterwards, the animal is given access to a mirror. If the animal looks at its own reflection, then touches the mark, it is assumed to have self-awareness – it knew the reflection was an image of itself, and not of another animal.

The mirror test has also been used on human children. Under the age of 18 months, most children think the reflection in the mirror is a playmate, and do not reach for the mark. But from approximately 18 months onwards, they gain some level of self-awareness, and start to reach for the mark.

Self-aware mammals

The first animals to pass the mirror test, in the 1970s, were some captive chimpanzees. This was a stunning discovery in animal psychology, and the first ever evidence that another species was conscious and self-aware.

In the next few decades, other mammals managed to pass the test. As well as several species of primate, orcas and dolphins have demonstrated self-awareness.

Another famous example was an Asian elephant named Happy, who passed the mirror test in 2006. Interestingly, two other elephants who took part in the test showed no signs of self-awareness. This suggests that different individuals in the same species can have different levels of consciousness.

Self-aware birds

Due to the successes of mammals in the mirror test, scientists began to wonder if consciousness was an exclusively mammalian quality. They linked it to the neocortex – a part of the brain that can only be found in mammals.

But in 2008, this theory was blown apart, when a group of five Eurasian magpies managed to pass the mirror test. Birds do not have a neocortex, which meant consciousness must be generated in a different part of the brain.

Other birds, such as New Caledonian crows, which perform so well in logical intelligence, have failed to pass the mirror test. The same is true in African gray parrots, which perform well in linguistic intelligence. Self-awareness must evolve separately from these other cognitive abilities.

Self-aware fish

The biggest surprise in the history of mirror testing happened in 2019. A groundbreaking study found that bluestreak cleaner wrasse – a tiny species of tropical fish – were able to pass the test.

It was such a shock, that Gordon Gallup, the inventor of the test, denied the findings. He did not believe that an animal as cognitively simple as a fish could possibly pass the test. But in 2022, a follow-up study generated the same results.

Ultimately, self-awareness has evolutionary benefits. It helps an animal to understand its role in a social group, to know the shape and size of its body, to recognize its strengths and weaknesses. It is little wonder that such a useful skill would evolve in so many species.

Criticisms of the test

The mirror test is the most established method for testing self-awareness, but it is sometimes criticized.

The test does not cater for species with poor visual skills, such as dogs. These animals can barely see a mirror, let alone the reflection of a mark on their body. A sniff test of self-recognition (STSR) has been explored for dogs, but for now, the species is officially listed as ‘not self-aware’.


Another concern is whether or not the animals feel motivated to touch the mark. When two elephants failed the test, in 2006, researchers wondered whether they actually liked the look of the mark, and decided to leave it where it was.

As well as this, some people argue that self-recognition is not the same as self-awareness. These species may know what their bodies look like, but are they truly conscious?

To be a bat?

If the mirror test is rejected, it leaves researchers in a difficult position. We might never be able to empirically test whether animals are truly conscious.

In 1974, philosopher Thomas Nagel published a famous paper titled *What is it like to be a bat?* in which he argued that we will never know whether other species are conscious. Their mental experiences are so remote from our own that we cannot ever hope to comprehend them.

Nagel’s argument has been widely discussed in the fifty years since its publication. While certain scientists agree with him, many believe that we will understand animal consciousness eventually. If we devote enough time to animal brains, surely an answer will be found.

Humans and animals

Whether animals are self-aware or not, one thing is certain: from logic and emotions, to space and memory, non-human minds have evolved in astonishing ways.

As people better understand this, it has real-world implications. In 2022, the United Kingdom passed the Animal Welfare (Sentience) Act, which legally recognized animal sentience, and promoted ethical treatment of other species.

But at the same time, forests are cut down around the world, despite evidence to suggest that primates are capable of grief. Some countries still hunt whales, and an octopus farm is under construction in Spain.

As a species, we must stop and ask ourselves: if animals are intelligent beings, should that change the way we treat them?


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