Perception and Gestalt Principles

Perception

• Perception is the process of recognizing information from sense organs.
• This process creates unity and coherence in sensory input.

Gestalt

• Gestalt principles organize and pattern stimuli to help us understand wholes rather than discrete parts.
• Figure-ground is distinguishing the main focus of attention from background or surroundings.

Form Perception

• Form perception is the organization of the visual field into objects that stand out from their surroundings.
• Examples of organizing principles include proximity, continuity, closure, similarity, and connectedness.

Illusion

• An illusion is a false or misleading impression caused by errors in perception or physical distortions.
• Illusory contours are perceived shapes that aren't physically present.

Delusion

• Delusions are false beliefs, often involving persecution or grandeur.
• These are frequently seen with psychotic disorders.

Hallucination

• Hallucinations are false sensory experiences.
• Experiences such as seeing something in the absence of an external stimulus can occur.

Optical Illusions

• Seeing is believing, but seeing isn't always believing correctly.
• Examples shown include various visual illusions.

Depth Perception

• Depth perception enables judging distance.
• Gibson and Walk suggested human infants (crawling age) and even newborn animals have depth perception.

Convergence

• Convergence is the result of vergence eye movements where the fixation point for each eye is identical.
• Feedback from these movements provides information about the distance of objects from the viewer.

Binocular Depth Cues

• Binocular depth cues involve both eyes to provide information about the distance of objects.
• Retinal disparity means the images from the two eyes differ. Looking at two index fingers held about an inch apart, a few inches from your eyes leads to a "finger sausage" effect.

Monocular Depth Cues

• Monocular depth cues: Information about depth that can be perceived with only one eye.
  • Relative Size: If objects are similar in size, the one with a smaller retinal image is perceived as farther away.
  • Interposition: Objects that block others are perceived as closer.
  • Linear Perspective: Parallel lines appear to converge in the distance. The more they converge, the greater the perceived distance.
  • Relative Height: Objects higher in the visual field are perceived as farther away.
  • Relative Motion: Objects closer to a fixation point move faster than those farther away.
  • Texture Gradient: Closer objects have a coarser and more distinct texture than distant ones.
  • Aerial Perspective: Distant objects appear hazy or blurry due to atmospheric particles.
  • Light and Shadow: Lighter objects appear closer than darker objects.

Perceptual Constancy

• Perceptual constancy refers to perceiving objects as unchanging, even with changes in illumination or retinal images.

Colour Constancy

• Perceiving familiar objects as having consistent colour despite changing illumination.

Shape Constancy

• Perceiving the shape of an object as constant even if its image on the retina changes.

Size-Distance Relationship

• The perceived size of an object is influenced by its perceived distance and object size.

Ames Room

• The Ames room is designed to cause a size-distance illusion.

Trichromatic Theory

• This theory posits that color perception results from mixing three distinct color systems: red, green, and blue.

Opponent-Process Theory

• Color perception is based on three systems of color receptors that respond in an on-off fashion to opposite color stimuli.
  • Blue-yellow
  • Red-green
  • Black-white

Perceptual Interpretation

• Immanuel Kant argued that knowledge comes from inborn ways of organizing sensory experiences, while John Locke believed we learn to perceive the world through experience.
  • What is the role of experience in perceptual interpretation?

Perceptual Set

• A mental predisposition to perceive one thing and not another.
• Flanking pictures can influence perception in the center.

Frame of Reference

• A framework for interpreting information, and helps to organize our experiences.

Bottom-Up/Top-Down

• Bottom-up processing starts with sensory receptors and works up to brain's integration.
• Top-down processing is guided by higher-level mental processes, like drawing on experiences and expectations.

Perception Revisited

• A combination of biological and psychological influences, and social-cultural factors contribute to perception to shape one's reality.

Science and ESP

• Extrasensory perception (ESP) is perception without sensory input, and most scientists do not believe in it.