A method used in behavior research, manipulation of overlapping rivalrous images by polarizing filters, or MORI, employs LCD projectors and polarizing glasses to test perception and memory. In a MORI experiment, two LCD projectors are used to project two different videos on a half-transparent screen. The test subjects view the movies together, wearing glasses that polarize the light from the screen differently, allowing them to see only one movie or the other.
Figure 2 from pg. 601 in "Surreptitiously projecting different movies to two subsets of viewers"
The light from projector A is polarized differently than projector B and the A and B groups of viewers have glasses that correspond to one projector’s polarization or the other. This method is useful particularly for studies on reliability of witness reports on crime. A typical set-up is one in which a mock-crime is filmed and small details like the color of a car, the size of an actor, or the time of day is changed slightly in order to create conflict between the two groups of viewers. This is especially useful when testing children since the previous method was to have confederates (people who are not actually test subjects, but are actors who know the goals of the study) insight conflict among the test subjects, but it is incredibly difficult to find reliable confederate children. The only difficulty with MORI is that if a participant tilts their head too much, the polarizer glasses will reveal the other movie being played. Usually, though, the subjects are unsuspecting of what the aims of the experiment are and the movies are short enough that the participants can remain alert and still for the necessary amount of time.
I found this use of LCD technology to be particularly interesting because it so effortlessly links the principles of polarization to a social science experiment. This research method very clearly expresses how physics (and, more specifically, the things we learned in Electromagnetism II) can be applied to vastly different areas of study.
References:
Mori, Kazuo. “Surreptitiously projecting different movies to two subsets of viewers.” Behavior Research Methods Vol. 35.4 (2003): 599-604. 10 April 2012. <http://www.springerlink.com/content/n2885j4541047k61/>.
This application – as you mentioned – represents a perfect connection between theoretical and applied physics in real-life situations. I can still remember imagining if it was possible to have to sets of people see two different images by simply giving them different optical lenses to wear – apparently it’s already being done! I am guessing that your project directly applies to this MORI process because the changing of colors in the movie is made possible by the twisting liquid crystal molecules in the LCD screens.