Stereopsis (Depth Perception)

Depth perception is the visual ability to perceive the world in three dimensions (3D) and the distance of an object. Depth sensation is the corresponding term for animals, since although it is known that animals can sense the distance of an object (because of their ability to move accurately or to respond consistently, according to that distance), it is not known whether they "perceive" it in the same subjective way that humans do.

Depth perception arises from a variety of depth cues. These are typically classified into binocular cues that are based on the receipt of sensory information in three dimensions from both eyes and monocular cues that can be represented in just two dimensions and observed with just one eye.[2][3] Binocular cues include stereopsis, eye convergence, disparity, and yielding depth from binocular vision through the exploitation of parallax. Monocular cues include size: distant objects subtend smaller visual angles than near objects, grain, size, and motion parallax.

Types of Stereopsis

Testing Stereopsis

Titmus Stereo Test

The Titmus Stereo test uses polarized glasses with vectograph images to simulate depth. It includes three tests for use under different circumstances:

  • The House Fly establishes the presence of gross stereopsis, especially useful for young children who may have difficulty understanding instructions.
  • The Circle patterns provide a finely graded sequence for critical testing.
  • The series of symbols, from which a forward-appearing one is selected, facilitates the testing of younger children.

Randot Test


Chopin A, Bavelier D & Levi DM. The prevalence and diagnosis of ‘stereoblindness’ in adults less than 60 years of age: a bestevidence synthesis. Ophthalmic Physiol Opt 2019; 39: 66–85.

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