Principles of Visual Perception and Gestalt Theory

Perceptual Records and Constancy

Human perception involves several records that maintain stability despite sensory changes:

• Size: Refers to the invariable size things have in our mind, although they vary from their size in reality.
• Constancy of Form: The apparent shape of objects is maintained from any angle from which they are contemplated.
• Proof of Albedo or Brightness: The sensation of brightness remains unchanged from the surface of an object. One should not confuse brightness with luminance.
• Color: Although the spectral composition of lights illuminating a target varies, it will still appear to be the same color.

The Origins of Gestalt Theory

Originating in Germany (1910) with Max Wertheimer, Wolfgang Kohler, and Kurt Koffka, Gestalt theory resumed the consideration of prior experiences, such as those of the Belgian Joseph Plateau, who had studied the kaleidoscope effect since 1830.

The Phi Phenomenon and Apparent Motion

Established in 1912, the Phi phenomenon (apparent motion) is based on two types of movement:

Alpha Movement

This occurs when a light is lit at a given power, size, and shape, and we perceive the light appearing to decrease or vice versa. They are grouped together in the perception (as seen in the drawing). It is also called spreading or concentration. This involves the same place and different strengths, often seen as light in darkness.

Beta Movement

This involves a light with the same output as another light located in a different place. When both turn on and off alternately, we perceive a single light that moves. This is also called "movement from one point to another" (different place, same power). The intervening time must be between 30 and 200 milliseconds.

The Process of Human Perception

Human perception is not merely the sum of sensory data, but a process that passes through a restructuring that is configured from that information into a form or "gestalt." When one attempts to analyze the individual parts, the gestalt is destroyed; this is the main problem within psychology.

In an organized whole, each individual part affects the others, the whole being more comprehensive than the simple sum of its parts. Wertheimer also studied the principle of organization or the Law of Praegnanz, which states that perceptual organization always tends toward the greatest simplicity, completing the whole world according to our interpretation and experience.

Key Gestalt Laws of Organization

• Law of Proximity: Things tend to cluster when they are close to each other, appearing distinct from more distant objects.
• Law of Similarity: The perceptual grouping of figures that share some common visual property, such as shape or color.
• Law of Directionality and Orientation: Elements contained in one direction that are aligned along the main figure belong to it, or according to the spatial orientation thereof.
• Law of Good Continuity or Uniformity: The tendency to perceive objects as a whole or that lines remain in the same direction.
• Law of Closure: If a figure is incomplete, the viewer completes it in their mind.
• Other Laws: These include the laws of contrast and inclusiveness.