  Stereoscopic 3D (S3D) displays provide an additional sense of depth compared
to non-stereoscopic displays by sending slightly different images to the two
eyes. But conventional S3D displays do not reproduce all natural depth cues. In
particular, focus cues are incorrect causing mismatches between accommodation
and vergence: The eyes must accommodate to the display screen to create sharp
retinal images even when binocular disparity drives the eyes to converge to
other distances. This mismatch causes visual discomfort and reduces visual
performance. We propose and assess two new techniques that are designed to
reduce the vergence-accommodation conflict and thereby decrease discomfort and
increase visual performance. These techniques are much simpler to implement
than previous conflict-reducing techniques.
