Are You Anosognosic?

Fol­lowup to: The Strangest Thing An AI Could Tell You

Brain dam­age pa­tients with anosog­nosia are in­ca­pable of con­sid­er­ing, notic­ing, ad­mit­ting, or re­al­iz­ing even af­ter be­ing ar­gued with, that their left arm, left leg, or left side of the body, is par­a­lyzed. Again I’ll quote Yvain’s sum­mary:

After a right-hemi­sphere stroke, she lost move­ment in her left arm but con­tin­u­ously de­nied it. When the doc­tor asked her to move her arm, and she ob­served it not mov­ing, she claimed that it wasn’t ac­tu­ally her arm, it was her daugh­ter’s. Why was her daugh­ter’s arm at­tached to her shoulder? The pa­tient claimed her daugh­ter had been there in the bed with her all week. Why was her wed­ding ring on her daugh­ter’s hand? The pa­tient said her daugh­ter had bor­rowed it. Where was the pa­tient’s arm? The pa­tient “turned her head and searched in a be­mused way over her left shoulder”.

A brief search didn’t turn up a base-rate fre­quency in the pop­u­la­tion for left-arm paral­y­sis with anosog­nosia, but let’s say the base rate is 1 in 10,000,000 in­di­vi­d­u­als (so around 670 in­di­vi­d­u­als wor­ld­wide).

Sup­pos­ing this to be the prior, what is your es­ti­mated prob­a­bil­ity that your left arm is cur­rently par­a­lyzed?

Added: This in­ter­ests me be­cause it seems to be a spe­cial case of the same gen­eral is­sue dis­cussed in The Modesty Ar­gu­ment and Robin’s re­ply Sleepy Fools—when patholog­i­cal minds roughly similar to yours up­date based on fabri­cated ev­i­dence to con­clude they are not patholog­i­cal, un­der what cir­cum­stances can you up­date on differ­ent-seem­ing ev­i­dence to con­clude that you are not patholog­i­cal?