Optometrist Party Trick: Fact Or Just A Joke?

According to a recent article in Clinical and Experimental Optometry, laughing can reduce binocular rivalry and stimulate the brain to see images with both hemispheres of the brain. This is contrary to the normal binocular rivalry, in which the brain subconsciously switches attention between two competing images. In this study it was demonstrated by the subject looking at an optical illusion, like the Necker Cube, and being told a joke. While laughing the subject noted she was able to see both sides of the cube.
"Pettigrew (the study's author) says the effect of laughter on perception makes a good party trick."