There was no control in the experiment. This "study" would carry a little more weight if they had also put the sudoku-ers in a room with an "unattractive female" (or just another person for that matter!) and compared the results.
Ugh.
I'm hoping that the article simply neglected to mention the control. It's hard to believe that the researchers would be so colossally inept as to forget to have a control group.