What they are finding is that when viewed through a tiny aperture, a single eye provides sufficient information for the brain to discern depth cues:

The effect of “vivid 3D vision” can be experienced with just one eye, a study has suggested.

Researchers at St Andrews University said a method using a small circular hole could have wide implications for 3D technology.

The study, published in Psychological Science, also has implications for people who have just one eye or difficulties with double-eye vision.

via BBC News – Seeing in 3D possible with one eye, St Andrews study suggests.