A crooked tooth. That funky mole. A pimple on your chin. When you stare into the mirror and pick apart the little imperfections, you're doing more than being too hard on yourself. In fact, that behavior—understanding that your reflection is you, and seeing how you differ from other people—is often taken as a demonstration of some complex cognitive gymnastics that not all species can pull off.

Since the 1970s psychologists have used mirrors to search for signs of self-awareness in both humans and animals. Along the way, they came to believe that humans were almost universally able to pass a mirror-based self-recognition test by 24 months of age. But a 2004 study published in Child Development called that idea into question. Researchers found the widely accepted finding only applied to kids from Western nations, where most of the previous studies had been done. Now, a study published September 9 in The Journal of Cross-Cultural Psychology is reinforcing that idea and taking it further. Not only do non-Western kids fail to pass the mirror self-recognition test by 24 months—in some countries, they still are not succeeding at six years old.

What does it mean? Are kids in places like Fiji and Kenya really unable to figure out a mirror? Do these children lack the ability to psychologically separate themselves from other humans? Not likely. Instead researchers say these results point to long-standing debates about what counts as mirror self-recognition, and how results of the test ought to be interpreted.

Strange results and 'freezing' behavior

The classic mirror test of self-recognition starts with a mark placed on a subject's body, somewhere he or she can't see it without help—such as the forehead or back of the shoulder. Then subjects are put in front of a mirror. To pass the test they have to first figure out that the reflection they see is not somebody else, understand that it is themselves, and then examine their bodies enough to find the mark. Finally, they have to realize the mark shouldn't be there and try to remove it.

The theory is that subjects who pass the test—animal or human—are self-aware, says Tanya Broesch, a doctoral candidate in Emory University's Department of Psychology and lead author on the 2010 study. That is, the subject understands the concepts of "self" and "others," can differentiate between the two, and can recognize themselves in the reflection. Based on results with Western children, psychologists have linked the age humans start passing the mark test with other milestones that happen around the same time, such as development of empathy. The ability to separate oneself from others is often thought of as a prerequisite for understanding that someone else might be hurt or sad, even if the beholder is not.

But when Broesch tried the mark mirror test outside the U.S. and Canada, she got some strange results. In Kenya, for instance, only two out of 82 children, some as old as six, passed. But the kids who did not pass were not psychologically damaged or lacking empathy. And most displayed what Broesch calls "freezing" behavior—the children did not greet or smile at their reflection. Instead, they stood still and seemed deeply uncomfortable.

Broesch thinks that freezing is indirect evidence of self-awareness. The kids didn't pass the mark test, per se, but their behavior still demonstrated that they knew they were looking at themselves. Diana Reiss, a professor of psychology at Hunter College in New York City, agrees. She works with animals, primarily dolphins, and she says that relying solely on the mark test to measure self-awareness can give you a false negative.

"I think it's gotten confused in the field. We've forgotten that the behavior itself is also an objective means of showing that the subject understands self," she says.

Take elephants for instance. In 2006 Reiss worked with Joshua Plotnik, head of elephant research at the Golden Triangle Asian Elephant Foundation in Thailand, running the mark test on three elephants. Only one passed, but the two that failed still demonstrated much self-aware behavior, such as making repetitive movements that showed they connected the image to themselves. Why didn't they go after the mark? Reiss and Plotnik, say it just might not be something elephants care much about.

"The mark test can be difficult to apply across species because it assumes that a particular animal will be interested in something weird on their body," Plotnik says. Primates are interested in such things—we're groomers. But elephants are different. They're huge and they're used to putting things on, not taking things off of their bodies, like mud and dirt."

Humans, animals and cultural understandings of self

Elephants, it seems, have unique expectations about the world, which influence the way they respond to the mark test. Their ambiguous performance on the test is an example of how different animals interact with their environments in different ways based on their physical abilities, and the behaviors which served their species well over millennia, says Pete Roma of the Institutes for Behavior Resources and Johns Hopkins University School of Medicine.

These tendencies weave themselves into the behavioral fabric of a species. Akin to an animal version of culture, it might explain why some not particularly vision-oriented creatures, such as dogs, fail the mark test. We're just not applying the test in a way that means something to them. Gorillas are another good example: for many years, nobody thought gorillas could pass the mark test. Turns out, the test was just very uncomfortable for them. Eye contact is a thorny social issue for gorillas, often leading to fights, several researchers said. More than that, gorillas are easily embarrassed, says Robert Mitchell, foundation professor of psychology at Eastern Kentucky University. Instead of messing with the mark in front of the mirror, they would sometimes go away, hide in a corner, and wipe the mark off there. Gorillas got what was going on, they just didn't respond the way we thought they should.

In a sense that's what Broesch thinks is happening with the Kenyan children. Raised differently than those in Western, industrialized countries, Kenyan kids have a different understanding about what is socially acceptable. And that socialization usually produces a false negative on the mark test. The test largely doesn't work for these cultures, and the kids are not likely to ever pass. The earlier research done on younger children, published in 2004 and 2005 by Heidi Keller from the University of Osnabrück in Germany, came to a similar, but slightly different conclusion. Keller assumed that non-Western kids would eventually pass the mark test; it just look them longer because their cultures emphasized interdependence over independence.

The difference is not about when the children develop self-awareness or empathy, Mitchell says. Rather, it has to do with their social conditioning. Kids raised in interdependent cultures learn from the earliest games they play how to be part of a group.

"They aren't supposed to look different so when they see that mark they're stunned," he says.

Meanwhile, children raised to be independent are taught games that emphasize how they are separate and unique. In fact, Western kids are much more likely to be raised with lots of mirrors around them, and to play games in which their parents point at those mirrors and say, "Who's that? Is that you?"

If the relatively small differences among human cultures can alter mark test results so profoundly, then we have to consider what researchers really learn—and don't learn—when they run the test on an animal.

There are two things we should take away from this. First, self-awareness is not a hard and fast line. Instead, it is probably a continuum. That is an especially important lesson to keep in mind with animal research. A species might have the skill, even if some individuals do not. This is true for chimpanzees, who do not all pass the mark test, and can lose the ability as they age. Linked concepts, like empathy, exist in species and individuals that are not able to pass a mark test. Rats, for instance, do not pass the mark but still engage in some limited empathetic behaviors. And passing the test does not mean an individual has self-awareness, or mirrors, all figured out. After all, it is not uncommon to see a human child pass a mark test and then immediately look behind the mirror, as though not quite getting what it is.

Second, the mark test itself is not the end all and be all of self-awareness.

"Self-awareness is like gravity," Johns Hopkins's Roma says. "We can't touch it directly, so if we want to measure it, scientists must develop valid techniques to directly observe its effects. Currently, mirror mark tests are the best-known and most accepted method, but the absence of an effect does not necessarily mean the absence of the thing we're trying to measure. Ultimately, evidence from multiple techniques should converge on the truth, whatever it may be. Such is the beauty of how scientific advances turn controversy into common knowledge."