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Tuesday September 27th, 2022

Monkey Mirror Test: Part 1

Our back garden monkey cousins may be more like us than we think

It haunts me, that photo. Though a trifle blurry, it’s a serendipitous snapshot: I didn’t even realize as I took it that it seemed to confirm what I suspected was happening.

We’re lucky at our house. A screen of trees rises beyond our little garden, mainly rooted in the compound of a mansion with a private pond just across the lane. The trees dance a lovely ballet when the breeze blows and we get sightings of cool birds like Green Imperial Pigeon and Crested Goshawk.

And every few days come the langurs. We generally hear them before seeing them as they shout their ooh-oohs while chasing each other through the branches. They scamper over the house roofs all around us but seldom come onto our property. We have a large-ish Labrador and also a fierce and fearless Golden Retriever, charming sweetheart of a girl, who chews the fur off wriggling chipmunk pups found fallen on the driveway, goes eyeball-to-eyeball with cobras, and one night killed an intruding civet cat in a fight that destroyed our vegetable patch, then left the corpse on our doorstep to enjoy when we woke up after having heard nothing of the dark struggle. How did she manage to get out of the dog house?

But a certain day back in November was different. A handful of langurs came to perch on our garden wall, reaching into our lemon tree, then peeling and munching the sour fruit. Maybe the dogs were asleep. I got the camera out and started snapping pics from our rear balcony. Then I began to notice something even more curious. There’s a house-and garden between our garden and the lane mentioned above. That little garden hosts six good-sized trees in which the primates frequently congregate, nibbling snacks and gazing at us as we gaze back. One of those trees provides easy access to the top of an air conditioning unit, placed on a shelf just below some windows on that house.

Monkeys gazing at mirror images of themselves


That day, one, two or sometimes three simians spent lingering interludes sitting atop the AC unit, appearing to look through the windows into the room there. What could be holding their interest? The house–owned by a gentlemanly, elderly national cricketer with grown children–has been uninhabited for quite some time now. There would be nothing to see in an upstairs room except motionless furniture and whatnot. How could that be so fascinating? 

As I shifted station to snap more pics, I noticed reflections of trees and sky in the windows. It hit me that the monkeys were gazing at mirror images of themselves. I began to glimpse those ghostly reflections. Snapping away as they leaned in and fidgeted, I had no idea until reviewing the pics later that I had caught a langur licking its own reflection.

For some five decades now, scientists have been experimenting with the Mirror Self-Recognition (MSR) test. What they are looking for is whether an animal is capable of grasping that it is seeing itself in a mirror. If so, we may perhaps infer that it is aware of itself as a self. 

You put one or more animals of a particular species in front of a mirror and watch what happens. In a typical first reaction, an animal thinks it is encountering another animal of its species. It may squawk with aggression or manifest other social behaviors. Most species never move beyond this. But some begin trying to puzzle out what is going on.

MSR literature describes phases that may follow this first social response phase. A second phase involves physical investigation such as looking behind the mirror. A third phase entails repetitive motions intently observed. As in that mirror scene in the Marx Brothers film ‘Duck Soup,’ this apparition does whatever I do at exactly the same time. This behavior gets characterized as Level One in what’s called ‘passing’ the mirror test. The animal seems aware of itself as a self because it understands that it is watching itself.

Scientists have been experimenting with the Mirror Self-Recognition (MSR) test looking to see if an animal is capable of grasping that it is seeing itself in a mirror


Maybe. For animals that reach this phase three, scientists introduce a confirmational phase four, typically embodied in the ‘spot’ exercise. They place a visible spot on a part of the animal’s body that it cannot normally see–its forehead, for example–and place it in front of the mirror. If the animal, upon seeing the spot in the mirror, then touches that spot on its own body, it must be grasping that the image in the mirror is itself. This could be called Level Two in passing the mirror test. Scientists reason that an animal capable of understanding its own image in a mirror possesses self-awareness: “ability to become the object of your own attention.”

Licking your own reflected tongue looks possibly like passing a self-administered version of the spot test. On the other hand, it could be consistent with the lower Level One (behavioral phase three) of the four-phase MSR progression. (This ghostly animal of my species does precisely what I do exactly when I do it. What if…?) For that matter it could even align with progression phase one, where the animal behaves as if interacting with another animal, albeit a weird one. I have found no discussion of rigorous mirror testing with langurs.

Scientist Gordon Gallup conceived the test one day while shaving in a mirror. Before long he was observing chimpanzees using mirrors to groom themselves—cleaning teeth, for example–and to scrutinize their genitals. To date, consensus has it that chimpanzees, bonobos, orangutans, bottlenose dolphins and Asian elephants like those found in Sri Lanka clearly pass the mirror test. Scientists link success on the test to high intelligence and social sophistication. Eurasian magpies represent the first non-mammals to pass. They try to remove colored stickers from their feathers while viewing them in a mirror. It’s not that they can feel the stickers. They do not try to remove invisible ones. Magpies are highly intelligent, of course, especially for an animal without a neocortex.

As interesting as those that pass the test are those that do not. Gorillas: not so much. Macaques and several other varieties of monkey do not pass, nor do lesser apes: gibbons and siamangs. So if langurs pass the test, they are punching way above their weight. In a great documentary about Polonnaruwa macaques, actress Tina Fey narrates a confrontation between a troupe of them and a gang of langurs. She disparages langur intelligence compared with her macaques. In this, she may be a trifle hasty. At least five documentaries so far have focused on Polonnaruwa macaques. Macaques are amazing and colorful to be sure, but could someone please aim a film cam at a few langurs for a while? 

If the animal, upon seeing the spot in the mirror, then touches that spot on its own body, it must be grasping that the image in the mirror is itself. This could be called Level Two in passing the mirror test

Self-awareness may go with recognition that other animals are also selves of their own. It may foster ‘theory of mind’: comprehension that other animals have desires and intentions of their own, along with accurate grasp of what those might be. This may correlate with generosity: sharing of benefits and assistance in peril.

If langurs can indeed ‘pass the test,’ such considerations seemingly oblige us toward enhanced concern for their well-being. Due to urbanization and habitat loss, Colombo’s endemic sub-species, our very own purple-faced langur, is listed ‘critically endangered.’

A graduate of Harvard Law School, Mark Hager lives in Pelawatte with his family.

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