When I can鈥檛 remember something, how do I know that I ever knew it in the first place?
John Ripley, Leeds, West Yorkshire, UK
We pay 拢25 for every answer published in New 杏吧原创. To answer this question 鈥� or ask a new one 鈥� visit newscientist.com/lastword. Terms and conditions apply.
Advertisement
This article appeared in print under the headline 鈥淭otal recall鈥�