Night vision goggles will cause which of the following effects?

• A. Blinding light if suddenly entering a well-lit environment
• B. Lack of depth perception
• C. A 3D effect of distant objects
• D. A shimmering beach effect on the horizon

Answer: (B)

Lack of depth perception happens because night vision goggles produce an intensified image that is effectively flat to the brain. Your normal ability to judge distance relies on several depth cues: how your eyes converge and focus, the slight differences between the two eyes (binocular disparity), motion parallax as you move, and other contextual cues. The NVG system presents a fixed-focus, two-tube image with a restricted field of view, which blunts or distorts those cues. As a result, estimating how far away objects are becomes unreliable, so depth perception is diminished. The other options describe effects that aren’t inherent perceptual changes from wearing NVGs (for example, sudden bright light can cause glare or washout under certain conditions, but that isn’t the primary perceptual change; NVGs don’t inherently create a true 3D effect or a shimmering horizon).