Follow this link to see an example of
the survey implemented by Matthew Atkinson, Ryan Enos and Seth Hill
in the winter and spring of 2007 for the paper
Atkinson, Matthew D., Ryan D. Enos, and Seth J. Hill. 2009. ``Candidate Faces and Election Outcomes: Is the Face–Vote Correlation Caused by Candidate Selection?'' Quarterly Journal of Political Science Vol. 4: No 3, pp 229-249, http://dx.doi.org/10.1561/100.00008062.
* Note that for the actual survey, there were no pop-up boxes indicating which face was chosen. After the selection, the screen automatically moved on to the next face pair.