Mirror, Mirror on the Wall: Dolphins and the Self-Recognition Test

August 12, 2015 Eve Copeland

This piece on dolphins and the self-recognition test is an overview of well-known studies that have changed our thinking of dolphins and nonhumans alike. 

The scientific community used to assume that having a sense of self is an attribute only found in humans and other great apes, but studies increasingly suggest that dolphins are much more self-aware than we originally believed.

In psychology, self-awareness is generally assessed using a classical paradigm: the Mirror Self-Recognition Test, or MSR. The general idea of this test is to subtly mark an animal with a colored substance somewhere on their body, then situate them in front of a mirror. If the animal orients their body to examine the mark in its reflection, they successfully pass the test. If the animal responds to their reflection as if it was another animal, they fail the test.

As simple as this sounds, the ability recognize one’s own reflection has only been observed under laboratory conditions in a few species, yet this alone has profound implications for self-awareness. Human beings don’t even gain this ability until they reach the age of 18-24 months, and this stage of development is considered to be a precursor to more complex forms of self-awareness, such as introspection (examining one’s mental and emotional processes) and mental state attribution (the ability to understand the emotions, beliefs, intents etc. of others).

To date, only a handful of animals have consistently shown the ability of MSR in the lab: some primates, Eurasian magpies, elephants and dolphins. During a dolphin MSR test, the researchers were confident that the subjects had definitively passed the test. For example, after undergoing several MSR tests with markings on different parts of his body, a male dolphin was marked on his tongue for the first time. After being marked, he immediately swam to the mirror and opened his mouth, a behavior he had never performed before during the experiment. This observation supports the idea that the dolphins were not only able to pass the test, but could do so with a level of familiarity that displays their complete understanding of the task.

One interesting difference between chimps and dolphins in MSR studies is that, unlike dolphins, chimps responded to markings placed on their chimp companions. One explanation for this finding is that chimps are social groomers and dolphins are not. What’s interesting about this is that, despite not having a culture of social grooming, the dolphins were still interested in inspecting their own image. Could this mean that, like humans, dolphins are curious about what they look like?

Though the authors of the study didn’t say one way or the other, it certainly seems possible. One convincing anecdote is how dolphins respond to reflective surfaces in general. When a mirror is placed on a tank, dolphins respond in an interesting way. They immediately swim over and nudge their tank-mates aside so they can take turns peeking at their reflection, playfully somersaulting and blowing bubbles in front of the mirror. Their reaction is reminiscent of little kids giggling at their distorted reflection in a funhouse mirror, or gathering around a computer to take selfies in a webcam. This behavior appears to demonstrate not only that dolphins have some idea of their individual selves, but is a testament to dolphins’ curious, creative, and playful personalities.

Photo by @atmoji