It shows how fast I did simple arithmetic problems (e.g., 2*0, 9-6, 7*9) before and after I started eating 1/2 stick (60 g) of butter every day. The x axis covers about a year. The butter produced a long-lasting improvement of about 30 msec.
More interesting stuff from Seth Roberts. I buy the argument broader argument about self-experimentation. I need to do more research to figure out what I should be doing.
check me out at posterous here.