Unit 2: Perception
Introduction to Perception
1. Sensation vs. Perception:
• Sensation: The process of detecting sensory stimuli from the environment.
• Perception: The interpretation and organization of sensory input into meaningful experiences.
2. Bottom-Up Processing: Analyzing information starting with sensory input and building toward a perception.
3. Top-Down Processing: Using prior knowledge, experiences, and expectations to interpret sensory input.
4. Sensory Adaptation: Reduced sensitivity to a stimulus after prolonged exposure.
5. Inhibition: The brain’s ability to suppress irrelevant sensory information to focus on relevant stimuli.
Depth and Constancy
6. Monocular Depth Cues: Depth cues that can be perceived using one eye. Examples include:
• Relative Clarity: Objects that are clearer are perceived as closer.
• Relative Size: Smaller objects are perceived as farther away if they are assumed to be the same size.
• Texture Gradient: Objects with more detail are perceived as closer.
• Linear Perspective: Parallel lines appear to converge as they recede into the distance.
• Interposition: Closer objects partially block the view of objects farther away.
7. Binocular Depth Cues: Depth cues that require both eyes. Examples include:
• Retinal Disparity: The difference in images seen by each eye; greater disparity indicates closer objects.
• Convergence: The degree to which the eyes turn inward to focus on a nearby object.
8. Visual Cliff Research: Experiments showing that depth perception is present in infants and other animals.
9. Perceptual Constancy: The ability to perceive objects as unchanging despite changes in sensory input, including:
• Size Constancy: Perceiving an object as having the same size despite changes in distance.
• Shape Constancy: Recognizing an object’s shape regardless of the angle of view.
• Color Constancy: Perceiving consistent color under varying lighting conditions.
Organizing Our Perceptions
10. Gestalt Principles: Psychological rules that describe how we naturally organize sensory information. Examples include:
• Figure-Ground Perception: The ability to distinguish an object (figure) from its background (ground).
• Similarity and Proximity: Grouping objects based on similarity or closeness.
Illusions and Other Phenomena
11. Color Afterimages: A visual illusion where a complementary color is seen after staring at a colored image and then looking away.
12. Reversible Figures: Images that can be interpreted in multiple ways, such as the Necker cube.
13. Illusions of Movement: Perceptions of motion where none exists, including:
• Phi Phenomenon: The illusion of movement created by rapidly blinking lights in sequence.
• Stroboscopic Movement: The illusion of continuous motion created by a rapid sequence of slightly varying images (e.g., in movies).
14. The Müller-Lyer Illusion: A visual illusion in which two lines of equal length appear to be different due to the direction of arrow-like endings.
15. The Ponzo Illusion: A visual illusion where lines of equal length appear unequal due to converging background lines.
Schemas
16. Schemas: Mental frameworks or concepts that help organize and interpret information, often based on prior knowledge and experiences.
17. Context: The surrounding information or environment that influences perception.
18.Perceptual Set: A predisposition to perceive things in a certain way based on expectations, context, and prior knowledge.