Mind Hacks has brought to my atten­tion a num­ber of inter­est­ing mirror-related studies:

Mir­ror Agnosia

[…] 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.

Mirrored-Self Misiden­ti­fi­ca­tion

[…] 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.

Me three.

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.

Mir­ror Agnosia and Mirrored-Self Misiden­ti­fi­ca­tion. How Big is Your Head?