Measuring aesthetics through timed tasks

There was a 2009 study by Christine Phillips & Barbara S. Chaparro entitled Visual Appeal vs. Usability: Which One Influences User Perceptions of a Website More? that looked at perceived usefulness and satisfaction for both low-appeal and high-appeal web sites. They varied the usability of both sights and observed what affect the variations had on user satisfaction and perceived usability of the site. Basically, they found that the perception of low-appeal websites did not improve much, even with objective increases in usability.


I'm wondering if an attempt has ever been made to study the impact of aesthetics on usability with respect to efficiency in completing tasks.  The time it takes to complete a basic task seems like a pretty reasonable measure of how usable a site is, and I think the activity could be defined both in terms one-time tasks as well as repeated tasks.


The idea would be to site people down and ask them to perform the activity on two versions of a site that are functionally identical. One version exhibits poor aesthetic design (maybe inconsistent fonts, etc.) and the other exhibits good aesthetic design. 


My suspicion is that it would take participants slightly longer to perform tasks on the site with poor aesthetic design because of eye fatigue, weariness, etc.  I think we instinctively know these can be the effects poor design but I haven't seen a study specifically structured in this way.


Please let me know if you're aware of one.. Thanks.