My latest story for Scientific American, More Than Meets the Mirror, is actually relevant to this blog (it doesn't happen very much!). It's about the relationship between body image and what's known as interoceptive awareness.
Are you cold? Thirsty? Hungry? Short of breath? Whatever your answer, you used interoceptive awareness to answer the question. Previous research has linked interoceptive awareness to the insula, and people with eating disorders have been shown to have deficits in both of these areas. But that didn't mean the two were necessarily related. After all, I have red hair and green eyes, but my green eyes didn't cause my red hair (for that, I thank Garnier Nutrisse Honeydip).
So a neuroscientist at the University of London devised an experiment where he tested students' interoceptive awareness by having them measure their heartbeat without taking their pulse. Then he used a trick known as the rubber hand illusion to trick the students into thinking that a rubber hand was actually a part of their body. Those students with low interoceptive awareness were more susceptible to the rubber hand illusion.
From the story (I do feel a little weird quoting myself, but whatever):
"People with low interoceptive awareness might have a less strict distinction between what is 'my body' and what is the external world," Tsakiris says. "They might be ruled more by vision, rather than by internal sensation." Previous studies have also found that people with anorexia have an impaired ability to sense internal cues, making the results of this new work useful for understanding and potentially treating severe body-image disturbance.
To be sure, the study used a small sample size and has not yet proved causation, but "if we can train people to sense their interoceptive states," Tsakiris says, "it might make a change in their body image. An interesting avenue for future research would be to see if improving interoceptive awareness impacts different areas of these disorders."