It shouldn't surprise you that we aren't born with the ability to recognize our own reflection. Self-recognition is a skill that can develop as early as 18 months in children. In their article, Self-Awareness, Social Intelligence and Schizophrenia, Gordon Gallup and his colleagues delve deep into just what it means to be able to identify yourself in a reflection.
So, you're not a vampire. What else?
The evidence provided by Gallup and his colleagues strongly suggests that the ability to recognize yourself in a mirror is closely related to your ability to conceive yourself as an individual, and infer information about the mental states of other individuals. As a matter of fact, self-recognition typically develops in humans around the same time as primitive social intelligence. In other words, whenever you can recognize yourself, you can try and piece together what other people are thinking or feeling.
On the flip side...
Species that fail to self-identify show no evidence whatsoever that they can infer information about the mental states of other individuals. I'm sure at some point you've all seen a cat or dog look at its reflection in a mirror. Normally, dogs will behave as if their reflection is another dog, and may bark or growl at its own reflection. Cats, from my experience, totally fail to give a single fuck about their reflections.
How do we know anything else can self-identify?
Gallup et al. provides an experiment in his article that was done using chimpanzees. The chimps had mirrors placed in their housing, and were given several days to grow accustomed to them. At first, the chimps behaved as if there was another member of their species with them. but after several days, the chimps began to use the mirrors to look at their bodies and groom themselves in new ways. Eventually, the chimps were sedated, the mirrors were removed and they had red marks applied to their bodies in places that were not visible without the use of a mirror. When the chimps were awake, fed, and watered, and the mirrors were reintroduced. The chimps began to investigate the marks, and even smelled their fingers after touching them. Orangutans and bonobos have also demonstrated self-identification skills, while evidence for the fourth great ape, gorillas, is mostly negative.
Do you see what I see?
As I said before, there is a strongly suspected link between self-recognition and the ability to infer information about the mental states of others.
Does this image make you cringe just a little bit? If not, get help. But the fact that I expected this image to conjure up that ungodly noise in your mind is an example of me making a social inference. If the ability to self-identify and the ability to make inferences about others is as closely linked as many suspect, then we can suppose that species that cant self-identify are incapable of empathizing with other of their species. And we would seemingly be correct.
In 1997, Anil et al. observed the reaction of pigs when they were shown the slaughter of other pigs. Or, rather, they observed the lack of a reaction. Besides mild stress caused by the jostling of the handlers, the pigs showed absolutely no distress while watching the slaughter of their piggy comrades.
The Cortex is the cause.
The ability to self-recognize and mental state attribution (infer what others are thinking) is believed to be located in our frontal cortex.
The right prefrontal cortex is considered the prime culprit for self recognition and mental state attribution. In a study by Keenan et al. subjects were asked to press one key if an image of their own face was shown, another if a friend's face was shown, and yet another if a stranger's face was shown. Now, many of you may have heard that the right side of the brain plays a larger role in the left side of the body. In fact, subjects were asked to press the keys first with their right hands, then with their left, and they identified their own face faster while using their left hands.
Self-recognition and mental health.
Schizophrenics will commonly react to their own reflection as if it were the reflection of a completely different person. In rare cases, some schizophrenics claim to see no reflection at all. Evidence suggests that a fascination with mirrors may be the precursor to schizophrenia, as many schizophrenics are extremely interested in mirrors and the images in them.
Many schizophrenics also struggle with the ability to identify what others are thinking or feeling. If a schizophrenic is told a joke where an assumption must be made about a mental state, they will have a very difficult time finding it humorous. Coincidentally or not, people with damage to their frontal cortex also display difficulty understanding these situations, as do children, whose brains have not fully developed yet. There is plenty of evidence now pointing to frontal lobe dysfunction as the cause of schizophrenia.
Putting it all together...
The abilities of self-recognition and mental state attribution obviously play an enormous role in our lives every day. If the key to these behaviors lies in our frontal cortex, as evidence suggests, there are many possibilities not only within the field of psychology but also medicine. Schizophrenia is a serious mental illness, and the key to understanding it is within our grasp.