Small fish passes classic self-awareness test

Small fish passes classic self-awareness test
Credit: bioRxiv (2018). DOI: 10.1101/397067

An international team of researchers has found a small tropical fish that is capable of passing a classic test of self-awareness. The results are published on the bioRxiv prepress server.

Since the 1970s, a developed by Gordon Gallup has been the gold standard for testing for —researchers make a mark on a creature's face and introduce a mirror. If the animal makes some attempt to touch or remove the mark, they are deemed to have self-awareness. Since the test first came into use, only a few animals have ever passed the test. Besides humans, the list currently includes chimpanzees, bonobos, orangutans, dolphins, elephants and pigeons. Others have responded in ways that have left their results in dispute. In this new effort, the researchers tested the relatively unknown cleaner wrasse—a tiny tropical fish. Prior research has shown that they have very good eyesight and go after parasites on the bodies of other fish. They are also very territorial.

To test the fish, the researchers first placed specimens in a fish tank with a mirror and watched what happened. As expected, the fish behaved as if viewing encroachments on their territory—they tried to attack their reflections. After giving the fish time to get used to the mirror, the researchers found they began exhibiting abnormal behavior—they bobbed as if watching themselves dance. Next, the team used a gel to mark the foreheads of the test fish—marks that the fish could only see when they looked in the . The researchers report that some of the test fish spent more time looking at their reflection, and that some of them actually tried scraping their face in the location of the gel, as if trying to remove it. The researchers claim this behavior indicates the fish passed the self-awareness test—they saw the mark on their forehead and tried to touch it in the only way available to them.

More tests will have to be done by others to prove the behavior was as it appeared and not just an attempt by the fish to grab and eat what they perceived as a parasite affixed to the head of a nearby .

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More information: Masanori Kohda et al. Cleaner wrasse pass the mark test. What are the implications for consciousness and self-awareness testing in animals?, bioRxiv (2018). DOI: 10.1101/397067

The ability to perceive and recognise a reflected mirror image as self (mirror self-recognition, MSR) is considered a hallmark of cognition across species. Although MSR has been reported in mammals and birds, it is not known to occur in any other major taxon. A factor potentially limiting the ability to test for MSR is that the established assay for MSR, the mark test, shows an interpretation bias towards animals with the dexterity (or limbs) required to touch a mark. Here, we show that the cleaner wrasse fish, Labroides dimidiatus, passes through all phases of the mark test: (i) social reactions towards the reflection, (ii) repeated idiosyncratic behaviours towards the mirror (contingency testing), and (iii) frequent observation of their reflection. When subsequently provided with a coloured tag, individuals attempt to remove the mark in the presence of a mirror but show no response towards transparent marks, or to coloured marks in the absence of a mirror. This remarkable finding presents a challenge to our interpretation of the mark test – do we accept that these behavioural responses in the mark test, which are taken as evidence of self-recognition in other species, mean that fish are self-aware? Or do we conclude that these behavioural patterns have a basis in a cognitive process other than self-recognition? If the former, what does this mean for our understanding of animal intelligence? If the latter, what does this mean for our application and interpretation of the mark test as a metric for animal cognitive abilities?

© 2018

Citation: Small fish passes classic self-awareness test (2018, September 4) retrieved 16 September 2019 from
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User comments

Sep 04, 2018
This does not really surprise me.
I don't think you need to be as smart as most people think to recognize yourself in a mirror. I also believe most animals are a lot smarter than most people think and sometimes extremely smart and talented in a narrow field/area/subject. At the same time they can be unbelievably stupid in other ways that seem totally obvious to us.


Somewhat like some people.

Sep 04, 2018
Among other things, to say the fish "passes the classic self awareness test" means that every member of the species behaves that way. The article says only some of the fish tried to scrape the gel away. What did the fish who scraped the gel away do afterward? Did they go back to watching their reflection as if it was another fish? How many of those who didn't have any gel on them scraped themselves?
In terms of the strange bobbing and dancing. It is possible the fish were merely trying to gauge the actions of what they saw as an intruder, trying to find a way to get behind them and attack them when the other fish seemed always to know what the fish being tested was going to do.
Again, too, notice that the article does not definitively claim that the wrasse is self aware, but the title declares it was definitively proved.

Sep 04, 2018
I'm also skeptical - were gel spots also applied to a control group without a mirror? Were there other controls to eliminate stresses of the skin or other senses by the gel or its application process?

Surely a good indicator of self-awareness and the implicit understanding of the principles of reflection would be a corresponding response to stimuli surreptitiously placed behind the subject, in view of the mirror? Ie. it would understand that the stimulus was actually behind it, not in front of it as it superficially appeared..

Sep 05, 2018
All animals are fully conscious. For example having eyes, without a consciousness to experience the sensory input from the eyes would be pointless and useless. Animals are not robots. My impression is that consciousness is the fundament of all life, even single cellular life.
The question of "self-awareness" tends to be based on an incorrect definition. Yes, perhaps not all animals recognize their own reflection when faced with a mirror. Of course animals have different eyesights than humans, and some may even perceive the reflection very differently from how we would. But regardless, their understanding of seeing themselves in their mirror does not depend on their self-awareness or consciousness, but on their intellectual comprehension of that image in the mirror. They may not be aware of what they themselves look like at all, may not intellectually relate the movements in the mirror to their own movements. But nonetheless be fully "aware" of their own self and fully conscious.

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