I'll take the last chocolate (and the first, and...)

Some researchers at the University of Michigan say if you know it is the last piece of chocolate, you tend to think it tastes better than the rest.

Ed O'Brien, who led the study, said "It is something motivational. You think 'I might as well reap the benefits of this experience even though it is going to end' or 'I want to get something good out of this while I still can'. " That sounds like a good guess.

If it was a matter of attention, you'd expect the first and known-to-be-last to focus the most attention. In this case they were explicitly asking people to evaluate the taste, so the loss of excitement from doing something over and over shouldn't be quite as big a factor. But they found 2/3 of the people who knew one piece was the last picked it; out of 5 choices. If they didn't know it would be the last they picked the last as the favorite 1/5 of the time.

The sample size isn't huge (52; I assume 26/26 for each group), so it needs a little followup. And of course if they'd gotten a null result this would never have hit the bits at the Telegraph, so there's a built-in bias.

After verifying this result, the obvious next class of tests is "What is the worst?"