We've probably all experienced it – getting frustrated by the user interface on a website, and wishing that the creators of that site could know just how angry they were making us. Well, in the near future, perhaps they'll be able to. It turns out that when we're upset, we move our mouse differently.

Led by Prof. Jeffrey Jenkins, a team from Utah's Brigham Young University had a group of test subjects conduct a timed online test. That test was rigged to get them mad, however. 

Every page of questions loaded very slowly, taking away from the time left for the subjects to formulate correct answers. They were subsequently penalized for their wrong answers, and then given feedback indicating that they had a lower-than-average intelligence.

Initially the volunteers moved their mice fairly smoothly, in straight lines or gently-curving arcs. As their frustration level increased, however, they transitioned to more jagged movements. Perhaps surprisingly, they also tended to move their mice slower as they got angrier. Jenkins believes that a similar difference may apply to users' swipes and taps on smartphone screens.

It is hoped that web developers could use such feedback to ascertain which areas of their sites need to be made more user-friendly. A spinoff company is now in the process of refining the technology for commercial use.

"Using this technology, websites will no longer be dumb," says Jenkins. "They can understand not just what you're providing, but what you're feeling."

Another Brigham Young scientist, Lijun Yin, is working on a system that identifies computer users' emotions by analyzing their facial expressions