While many people enjoy S-3D, it is a well-known fact that a minority of the population is not able to perceive S-3D. These people have problems with stereopsis, or the ability of our brain to unconsciously fuse two 2D images into a single 3D percept. In clinical practice, several stereopsis tests are used to measure this deficiency. Most of these tests are expensive paper-and-pencil tests requiring trained observers. In this paper, we discuss a recently developed method to test stereopsis on active shutter glasses displays. This allows researchers in the lab or S-3D users at home to test stereopsis in a free and easy way. Furthermore, we were interested in the distribution of test scores. More specifically, we wanted to know if our test resulted in a continuous (graded stereopsis) or bipolar (stereopsis present or not) distribution. Results of a preliminary study (N = 128) showed evidence for the second.