Part of the show Sex Chromosomes, Genetics and Food Webs
Mary in Suffolk asked:
Is there any scientific reason why a key suspended from a length of string held over food always seems to indicate correctly whether I can eat a particular food? If I eat anything containing MSG (monosodiumglutamate) in any form, I get a very severe migraine. If it rotates clockwise then the food is taboo, but if it rotates anticlockwise then the food is ok for me to eat. I really can't believe that this is true.
Sorry Mary, but we can't believe it's true either. I imagine that any spinning is more to do with the twist of the cotton that you hang the key on than anything else. There's probably a bit of gambler's fallacy kicking in there. You're expecting the right answer and therefore the result happens.