Fish looks in mirror, sees something on its face

February 10, 2019 6:32 AM

"A fish, the cleaner wrasse Labroides dimidiatus, shows behaviour that may reasonably be interpreted as passing through all phases of the mark test." The mark test, or mirror test, is a classic measure of whether an animal has self-awareness. The fish joins a short list of animals including great apes, a single Asiatic elephant, dolphins, orcas and the Eurasian magpie. The study has received mixed reviews, and the journal published a more cautious interpretation alongside the main article.
posted by clawsoon (10 comments total)

You wanna talk intelligent fish? Allow me to introduce you to mormyrids. They have huge brain to body mass ratios, in the same realm as birds and mammals. Some species devote up to 60% of their oxygen consumption to their brains. And they use these big brains to process and interpret electrical signals in their environments, including signals generated in the electric organs of other mormyrid fish for the purposes of communication. If that sounds uncannily like telepathy, you're not far wrong. They are seriously interesting animals.
posted by Anticipation Of A New Lover's Arrival, The at 6:55 AM on February 10, 2019 [14 favorites]

I've wondered about the test for species that don't have vision as their primary sense.
posted by Nancy Lebovitz at 7:33 AM on February 10, 2019 [1 favorite]

Well, a lot of folks strongly believe that current methods for testing animal intelligence seem to implicitly define "intelligent" as "thinks like a human," and that this is some serious bullshit that calls into question the fundamental validity of much of that field. Acknowledging that too loudly would be bad for people's careers though, so mostly we keep doing the same things we've been doing even though a lot of it sort of misses the point.
posted by Anticipation Of A New Lover's Arrival, The at 7:36 AM on February 10, 2019 [6 favorites]

You wanna talk intelligent fish? Allow me to introduce you to mormyrids.

I’ve long been fascinated with mormymids; including their large brain size. Does it translate to intelligence? When I was last really thinking about it and trying to find an answer, probably 10 or more years ago, there wasn’t much information available.

I used to have elephant fish, and work in a fish store. One of the more popular pieces of wisdom was that they couldn’t be kept in groups in aquariums. But in the wild, they were social and lived in schools. I really wanted a school to observe, though. But they’re hard to observe anyway, being they prefer the darker, hidden areas and are more active at night.

They’re also adorable when they eat the black worms I would feed them. They have this mouth they just slurp them up like spaghetti, and will sorta chew them adorably.
posted by [insert clever name here] at 9:48 AM on February 10, 2019 [5 favorites]

But I should add, the long “snout” pictured in the Wikipedia article is actually a feeler protruding from the lower jaw. They have this tiny round mouth above it.
posted by [insert clever name here] at 9:50 AM on February 10, 2019 [1 favorite]

My crotchety answer above notwithstanding, the authors of this paper recognize pretty explicitly that their results have as much to say about the validity of the mark test for self-awareness as they do about whether L. dimidiatus are self-aware. At the end of their abstract they say this:

This remarkable finding presents a challenge to our interpretation of the mark test—do we accept that these behavioural responses, which are taken as evidence of self-recognition in other species during the mark test, lead to the conclusion that fish are self-aware? Or do we rather decide that these behavioural patterns have a basis in a cognitive process other than self-recognition and that fish do not pass the mark test? 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?

They also talk about how it's difficult to apply the mark test to species that don't e.g. have hands. It would naturally also be impossible to apply it to a species that lacked vision, as many species do. Does not having hands make you not conscious? That seems ridiculous. Our anthropocentric conception of intelligence is very much at the heart of this study.
posted by Anticipation Of A New Lover's Arrival, The at 10:18 AM on February 10, 2019 [4 favorites]

If you find these questions interesting, I cannot recommend What a Fish Knows strongly enough.

For my part, I've always assumed all animals have inner lives and some sort of self and human arrogance is the only reason people think not.
posted by dame at 12:48 PM on February 10, 2019 [3 favorites]

Yeah, dame. Simpler inner lives, maybe, but some kind of consciousness on some level. Although there are also animals that I'd struggle to think of as conscious at all. Salps, for instance. Jellyfish. I could certainly see it being a fuzzy boundary, rather than a bright line, between consciousness and non-consciousness. An interesting fuzziness, though.
posted by Anticipation Of A New Lover's Arrival, The at 3:53 PM on February 10, 2019

Anticipation, your comment ^ reminded me of this fuzzy boundary belief.
posted by bryon at 9:23 PM on February 10, 2019 [1 favorite]

This is a very nice study. And yes, the authors explicitly take the position that their results don't necessarily imply that cleaner wrasse have self-awareness, but instead that the mirror-mark test doesn't form an adequate assessment of self-awareness. Although its proponents continue to insist that only a small number of species successfully pass the mark test, to a lot of people in animal behavior the maintenance of this elite list seems to rely on a lot of goalpost-moving. A couple years ago I co-authored a short commentary on, and published alongside, one of the studies cited by this paper; in that study, rhesus monkeys were able, with some training, to pass the mark test. But mark-test proponents argue this study doesn't really count because the monkeys were trained rather than reacting fully spontaneously, but in fact they were only really trained to assign some sort of significance to the mark on themselves. "Passing" the mark test depends as much, if not more, on the animal having some motivation to react to a mark on itself as it does on some special cognitive capacity.

Cleaner wrasse are a great choice for illustrating this point, as their ecological niche is as parasite removers, and as such they are very attuned to visually recognizing blemishes or other potential parasites, and have a strong innate motivation for reacting to them. What I think this study shows, and what the authors also seem to think, is that the mirror-mark test is an interesting but limited tool for probing animal cognition, and one I'd further add was conceived almost 50 years ago with a very anthropocentric perspective on the nature of intelligence. It's attracted outsized attention over the last five decades relative to its merits, and it's past time we stopped using it as a major touchstone for comparative cognition. Animal behavior and cognition are too dependent upon ecology and developmental factors for a one-size-fits-all approach to have much validity.

Frans de Waal's "more cautious interpretation" linked in the FPP is I think a pretty reasonable take, perhaps more generous than mine towards the mirror-mark test.

Anyway, cleaner wrasse and mormyrids are great, and I'm glad to see them getting love in this thread!
posted by biogeo at 10:08 PM on February 10, 2019 [3 favorites]