Perceptual Defense
A psychological phenomena known as perceptual defense occurs when people unconsciously suppress or misrepresent sensory data that they deem to be alarming, upsetting, or at odds with their expectations or beliefs. This defensive system shields the person from unpleasant or anxiety-inducing stimuli while functioning outside of conscious awareness.
An actual case of perceptual protection is observed in people with acrophobia, or a fear of heights. Consider an acrophobic visiting a glass-floored, lofty observation deck. Even if the glass is clear, the person may unintentionally turn away from gazing down or even believe that the floor is made of less transparent or opaque material than it actually is. The person uses this distortion of perception as a coping technique to protect themselves from the dread and anxiety that come with heights. The person lessens their psychological comfort and lessens their emotional suffering by avoiding or warping their perception of the hazardous stimuli, in this example, heights.