Mind Hacks has brought to my attention a number of interesting mirror-related studies:
[…] a condition where people lose their sense of reflection.
In these cases, the patient still has intact knowledge about mirrors, they can describe what they do and how they work, but they can’t seem to put it into practice.
For example, the patient stands in front of a mirror and the researcher holds a pen over the patient’s shoulder and asks him to reach for it. Most people would reach backwards, people with mirror agnosia reach forwards and bang their hand into the glass.
[…] a delusional variant where patients look into the mirror, see themselves, and believe it is another person.
How Big is Your Head?
[…] the mirror image of your head (as it appears to you) is exactly half its true size, irrespective of how far you are from the mirror, a fact that few people realise.
They also found that most people believe the mirror image of their own head will grow smaller as they move away from the mirror – it doesn’t it stays the same. Yet most participants correctly realised that if they watched the mirror image of another person’s head, it would get smaller as that other person moved away from the mirror. Finally, only a minority of participants realised that the size of the mirror image of another person’s head would get bigger as they, the participant, moved away from the mirror. Confused? Me too.
This type of stuff absolutely fascinates me and is why I read—and highly recommend—Sacks’ The Man Who Mistook His Wife for a Hat.