Module_2.1b

Unit 2: Cognition

Module 2.1B: Perception - Perceptual Organization and Interpretation

Learning Targets

• LT 2.1-3: Gestalt Psychology

  • Explain Gestalt psychologists’ understanding of perceptual organization.

  • Discuss figure-ground and grouping principles contributing to perception.

• LT 2.1-4: Depth Perception

  • Describe how binocular and monocular cues allow 3D perception.

  • Discuss motion perception.

• LT 2.1-5: Perceptual Constancies

  • Explain how perceptual constancies create meaningful perceptions.

• LT 2.1-6: Effects of Experience on Perception

  • Describe research on restored vision, sensory restriction, and perceptual adaptation.

Gestalt Psychology

• Definition: Gestalt means "an organized whole"; emphasizes integrating pieces of information to create meaningful wholes.

• Mechanisms: Sensations must be organized and interpreted, often unconsciously, filtering incoming information to construct perceptions.

Figure-Ground and Grouping Principles

Figure-Ground

• Concept: Visual field is organized into objects (figures) standing out from their surroundings (ground).

Grouping Principles

• Grouping: Tendency to organize stimuli into coherent groups.

  • Proximity: Group nearby figures together (e.g., seeing three sets of two lines instead of six separate lines).

  • Similarity: Group based on similarity (e.g., different colored circles perceived as distinct groups).

  • Closure: Fill in gaps to create complete shapes (e.g., assuming partially blocked circles are complete).

Other Grouping Principles

• Continuation: Objects intersected are perceived as single uninterrupted forms.

• Symmetry: Symmetrical shapes perceived as whole objects around their center.

Depth Perception

• Definition: Ability to see in three dimensions and judge distance.

• Visual Cliff Experiment: A device testing depth perception in infants.

  • Findings reveal development of depth perception correlates with independent movement.

  • Infants that have just learned to crawl are more willing to cross a visual cliff than those who have crawled for longer.

Binocular and Monocular Cues

Binocular Cues

• Definition: Depth cues that depend on two eyes.

  • Convergence: Inward angle of eyes for nearby objects.

  • Retinal Disparity: Comparing retinal images from both eyes; greater disparity indicates closer objects.

Monocular Cues

• Depth cues available with one eye alone.

• Include:

  • Linear Perspective: Parallel lines appear to converge in the distance.

  • Interposition: If one object blocks another, it’s perceived as closer.

  • Relative Size: Larger objects appear closer.

  • Texture Gradient: Densely packed objects appear further away.

Motion Perception

• Stroboscopic Movement: Perception of continuous movement from differing still images.

• Phi Phenomenon: Illusion of movement from adjacent lights blinking in succession.

• Autokinetic Effect: Illusion of movement in a still light spot in a dark room.

Perceptual Constancy

• Definition: Perceiving objects as stable despite changing sensory input.

  • Color Constancy: Familiar objects perceived as having consistent color despite illumination changes.

  • Brightness Constancy: Perception of constant brightness depending on context and relative luminance.

  • Shape Constancy: Perception of constant form regardless of changing retinal images.

  • Size Constancy: Objects perceived to have constant size despite distance variations.

Influence of Experience on Perception

• Research by David Hubel and Torsten Wiesel (1964): Demonstrated critical periods for visual development using kittens.

  • Findings: Impairing vision at early stages leads to long-term deficits due to reallocation of visual processing.

Perceptual Adaptation

• Definition: The ability to adjust to changed sensory inputs; includes experience of restored vision post-blindness.

  • Humans adapt to distorted visual input, e.g., using inversion goggles shows adjustment over time.

Practice Questions

• Examine the Concept: "The whole may exceed the sum of its parts."

• Explain convergence and retinal disparity in relation to depth perception.

• Apply concepts of figure and ground in perception of performers in a band.

• Describe monocular cues used in a realistic depiction of a scene.