Human Perception: Theories, Gestalt Principles, and Disorders

Theories on the Mechanisms of Perception

Associationism Theory

Wundt: Isolated sensations are perceived and then associated with others to form a global perception of the object.

Gestalt Theory

Studies the way in which perception is organized. Given a stimulus, individuals react differently.

Functionalist Theory

James: Stresses the subjective aspects of all perception.

Cognitive Theory

Neisser: Emphasizes the structural activity of the subject based on past experience.

Gestalt Principles and Laws of Perception

A) Figure-Ground Principle

We perceive a figure against a background, often denying the other. Both the figure and the background can be reversible.

Contour Law: The figure stands out against the background, marked by a clear boundary.

B) Law of Prägnanz (Good Form)

The tendency to perceive incomplete stimuli as complete or to fill in what remains unfinished.

Law of Closure: We tend to complete figures that are represented as incomplete.

C) Principles of Perceptual Grouping

Several simple stimuli are perceived grouped into more complex forms.

• Law of Continuity: Stimuli that have a continuity of form are perceived as forming part of the same figure.
• Law of Proximity: Similar stimuli that are close to each other will tend to be perceived as a whole or grouped to form a shape.
• Law of Similarity: Like or similar things are perceived together as part of the same set.
• Law of Closure (Reiteration): An open or incomplete stimulus tends to be closed immediately.

D) Perceptual Constancy

What we perceive is stable or constant, even though the size of objects, depending on our position, may vary.

Law of Apparent Movement: Movement is perceived when, in fact, there is none. This occurs due to an interval between two stimuli.

Perceptual Disorders

Hallucinations

Perception without an external object, where the subject believes they can actually perceive non-existing items such as voices, smells, or visions.

Hallucinosis

The perception of a stimulus that does not correspond to a real object. The subject perceives an object that does not exist in reality but is able to recognize the falsehood and regards it as abnormal.

Pareidolia

Deformation of real objects, but the deformation is caused by imagination. The individual maintains a view of reality and is aware of this distortion.

Illusions

Characterized by the object existing in reality, but it is perceived as deformed, distorted, or different from what it truly is.