Visual crowding

Visual crowding is the inability to view a target stimulus distinctly when presented in a clutter.

[8] Crowding is also asymmetrical meaning that a single flanker at an eccentric locus higher than the target makes it harder to identify the target than the single flanker at an eccentric locus closer to the fovea.

[31] Neurophysiological studies have not made much progress in narrowing down the locus of the brain at which crowding occurs.

Previous researches have demonstrated that crowding is “dichoptical” meaning that the target is perceived by one eye and the distractor by the other.

[18] Different studies implicitly assume that crowding is a unitary effect due to a single stage of processing.

This notion supports the view that crowding is influenced by the similarity and configuration of flankers and the target.

Herman Bouma, a Dutch vision researcher and gerontologist stated, “For complete visual isolation of a letter presented at an eccentricity of φ deg, … no other letters should be present within (roughly) 0.5 φ distance.

Critical spacing is the sufficient distance needed for the identification of an object among its flankers in the retinotopically organized cortex.

Bouma explains how the effect of crowding is dependent on the eccentricity of a subject and the distance between the flankers and the object.

Many studies support the claim that critical space needed for crowding depends on the eccentricity of the subject.