The Mirror Test

An article published in August by Cold Spring Harbor Laboratory, New York, in its online journal bioRXiv, is headed ‘Cleaner wrasse pass the mark test’. The story was picked up in various more popular science publications and in the general media, for this is a much-loved line of research with them – the line in question being clearly announced in the heading which the Daily Mail gave its own account: “Tiny fish is the first to pass the self-awareness test by recognizing its reflection in a mirror.” Or to sum up, in a twitter comment, the sudden claims now being made on behalf of this fish, “Cleaner fish are AWESOME! They show self-awareness.”

The research itself was somewhat less conclusive. Ten of these cleaner wrasse fishes (Labroides dimidiatus) were put into a tank which contained a mirror. At XRF-Labroides_dimidiatusfirst they treated their own reflections as intruders into their territory and acted accordingly. Then, becoming used to the mirror, they behaved in a more improvised manner, apparently testing out the mirror with “idiosyncratic postures and actions”. Finally they seemed to use the mirror more as humans might, showing “self-directed behaviour”. This behaviour most specifically included scraping off marks (hence the ‘mark test’) which had been applied to their skin under anaesthetic and were designed to be undetectable to the fishes except in their own reflections.

The conclusion which the authors reach in their report is that the fishes did indeed show responses of the sort recorded for previously ‘successful’ species, notably chimpanzees, elephants, dolphins, and magpies. Therefore, if those former experiments are to be regarded as having demonstrated self-awareness in the animals concerned, so must these be: cleaner wrasse, then, must be “self-conscious and have a true theory of mind” (i.e. awareness of their own mind and motives, and of those which others may have). However, faced with this ambitious imputation, the authors very reasonably prefer to argue that the test itself is unsound, or at least has been over-interpreted in the past. The test shows, they suggest, no more than an animal’s awareness of its own body (surely a necessity for survival) and the ability to learn that a mirror can enhance this awareness. And indeed other research has shown that pigeons and even ants (please accept the ‘even’ for now) can put a mirror to such use. To claim self-awareness for all these creatures would be to make it an ordinary condition of life – which perhaps it is, but nobody so far does assert this; on the other hand, to claim it for apes and dolphins who ‘pass’ the test, but not for these other less prestigious creatures, would be (I’m delighted to find these scientists saying) “taxonomically chauvinistic” – i.e. speciesist.

The authors of the article end by suggesting that “many more species may be able to pass the test when it is applied in a manner that is sympathetic to their natural biology.” This is surely true, and in fact the ethologists Mark Bekoff and Roberto Gatti have adapted the test for dogs by using the scent of the dogs’ own urine as the ‘reflection’. For of course making it a test of vision, the primary sense for humans but not for every animal, inevitably ties it to what humans do, makes it in fact a set of comparisons with ourselves.

And indeed that is just what it always has been. The hidden or (in more popular versions) expressed question has always been not just ‘How like us is this animal?’ but ‘How nearly as clever as us is this animal?’ Hence the strangely unscientific terminology which has been characteristic of this line of research, and which we’ve already seen instances of. Thus, elephants who seemed to recognize themselves in a mirror, as we were told in the leading professional journal Science a few years ago, “have joined the elite group”. The same journal more recently reported on a similar capacity in some magpies: only two out of the group of birds “passed the test”, but this is apparently “similar to the success rate in chimpanzees.” To sum up: passing the mirror test, so this article says,

is regarded as evidence of knowing who you are – a higher neural skill underlying human abilities such as self-consciousness and self-reflection. Researchers have given the test to a wide variety of species. Most fail.

Fail! It’s a wonder (I know the point has already been made elsewhere in this blog) that these second-string animals manage at all. You’d have to feel sorry for them.

This new research with cleaner wrasse, and its revision of the standard interpretation of such research, ought to help correct the absurd anthropocentrism of the mirror-test tradition, and is accordingly welcome. Even so, it’s sad to see these strange and fascinating animals (already demeaned and abused as decorative fishes for aquaria) emerge into the light of intellectual attention for this irrelevant reason, that they may ‘know who they are’ or at any rate be able to learn how to use a mirror. The beauty and complexity of their niche in coral reefs, where they eat the parasites and other unwanted material off ‘client’ fish, and indeed help to keep the whole coral system clean, makes this mirror test crude and reductive. It’s really a part of the ‘smarter than we thought’ genre of research, which itself has some relation to the amusement of dressing animals in human clothes. It all amounts to preening ourselves in the rest of nature: in short, making a mirror of it, for of course we are, as a species, mirror-addicts.

As to the ethics, the testing of the cleaner wrasse had the blessing of the Animal Care and Use Committee of Osaka City University, where the research was done, and we must suppose that the Committee meant what it said. But these mirror experiments are necessarily tainted with the cruelty of the behavioural psychology tradition, and their earlier versions, at least, show as much. The originator of the MSR test (mirror self-recognition) was Gordon Gallup, from Tulane University’s Psychology Department – always an ominous location for research animals. Gallup published his first report on the subject in 1970. His subjects were four “pre-adolescent” chimpanzees, born in the wild (a happily mirror-free environment, ensuring that they’d had no practice). Here’s what happened to them:

Each animal [the report goes] was placed by itself in a small cage situated in the corner of an otherwise empty room. [Remember that a sense of self is what’s being looked for in the animals who are being treated thus.] After two days of isolation in this situation a full-length mirror was positioned 3.5 metres in front of the cage to provide enforced self-confrontation. Observations of the animal’s behaviour were made by watching his reflection in the mirror through a small hole in an adjacent wall. After 2 days (8 hours each) of exposure to the reflected image, the mirror was moved to within 0.6 m of the cage and left in that position for 8 days … etc.

It’s a miserable performance, with its bleak and meaningless setting, cruel isolation of the juvenile animals, and “enforced self-confrontation”, all tending to rule out natural behaviour, and then the scientists squinting at it all through a hole, like Peeping Toms. (For more on this last particularly unpleasant dimension in animal research, see the petition set up earlier this month by Peta under the heading ‘Sex, Violence, and Vivisection; Are Some Animal Experimenters Psychopaths?’, noted below. I’m not, of course, suggesting that Gallup or his assistants were of this kind.) And although these unpleasant proceedings were offered as “the first experimental demonstration of a self-concept in a sub-human form”, the experiments with cleaner wrasse, to say nothing of pigeons and ants, have since suggested that very little was really being discovered.

Reports on MSR in the more popular science press and other media (which, as I say, love all this kind of ‘smarter than we thought’ research) are frequently headed ‘Mirror, Mirror’, to give the science a brightening connection to a familiar saying, the wicked stepmother’s refrain in the folk story of Snow mirror, mirrorWhite. Evidently it’s not done with any serious thought, because that story, so far from representing as an evolutionary boon the sort of self-awareness dramatized by correct use of the mirror, shows it as a source of neurotic restlessness and self-doubt. And that indeed is the mirror’s habitual character in the fictions where it appears. Here’s a trio of the finest of these, with the dominant sentiment in each case: Thomas Hardy’s poem ‘I look into my glass’ (self-pity), Sylvia Plath’s ‘Mirror’ (helpless protest against ageing), Shakespeare’s Richard II  (the king calls for a mirror, trying unsuccessfully to authenticate himself). These instances, with their sadly alienated mirror-gazers, don’t prove anything of course, but they represent a tradition of intelligent distrust of the kind of self-awareness that the mirror represents, and the “self-directed” mind and life which go with it.

No doubt this capacity to see and think we know ourselves, as individuals, groups, nations, and even species, has been essential to the rise of humanity, for good or ill. But we should admire the talent cautiously, cease to regard it as one of nature’s top prizes, and cease to teach it (or think we’re teaching it) to other animals. It’s not, after all, what is most needed by us now, or by them at all. The animal-activist son of a professor of psychology in Karen Joy Fowler’s brilliant novel We Are All Completely Beside Ourselves puts it thus:

We need a sort of reverse mirror test. Some way to identify those species smart enough to see themselves when they look at someone else. Bonus points for how far out the chain you can go. Double bonus for those who get all the way to insects. [my italics]

Or as Albert Schweitzer said in one of his Sermons on Reverence for Life, “Wherever you see life – that is you!”


Notes and references:

The full article from bioRXiv, posted 21 August 2018, is linked here:  The twitter comment was posted alongside the short version of that article.

The Daily Mail online reported the research on 31 August.

An article on self-awareness in dogs, as tested with urine samples, can be seen at

The Science article about elephants (‘Jumbo Reflections’) appeared in the issue for 30 October 2006, and about magpies (‘The Magpie in the Mirror’) on 19 August 2008. The report by Gordon G. Gallup Jr on his chimpanzee experiments (‘Chimpanzees: Self-Recognition’) appeared in Science on 2 January 1970.

The Peta report and petition can be found at

The quotation from We Are All Completely Beside Ourselves is at pp.201-2 of the edition published by Profile Books, 2014. Albert Schweitzer is quoted from A Place for Revelation: Sermons on Reverence for Life (Macmillan, 1998), p.10, translation by David Larrimore Holland. The sermons were originally preached in 1919, in the Church of St Nicolai, Günsbach. The saying is not Schweitzer’s own, of course, but is at least as old as the Hindu Upanishad from which he borrows it.

The sketch of Labroides dimidiatus is by Xavier Romero-Frias, and the illustration of the Snow White story comes from a 1916 re-telling in Europa’s Fairy Book.



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