1. The ambiguity effect: Jack is looking at Anne but Anne is looking at George. Jack is married but George is not. Is a married person looking at an unmarried person? Possible answers are “yes”, “no”, or “cannot be determined”.

The vast majority of people will say “cannot be determined”, simply because it is the first answer that comes to mind – but careful deduction shows the answer is “yes”.

2. Countries where chocolate consumption is high tend to produce more Nobel prize winners. But ironically Sweden, home of the Nobels, is one of the few that didn’t fit the pattern. Why and why? [Don’t know].

[New Scientist, 30 March 2013, pp. 32 and last page].