Introduction to Perception

Introduction to Perception

• Perception is the process of selecting, organizing, and interpreting sensory information to create a meaningful experience of the world.
• It is shaped by bottom-up (sensory data) and top-down (prior knowledge and expectations) processing.
• Perception is actively constructed by the brain, not a passive process.

Key Concepts in Perception

• Sensory receptors: Specialized cells detecting physical stimuli (e.g., light, sound, pressure).
• Sensory adaptation: Decreasing sensitivity to a constant stimulus over time.
• Transduction: Converting physical stimuli into neural signals.
• Absolute threshold: Minimum stimulus energy detected 50% of the time.
• Difference threshold (Just Noticeable Difference): Minimum difference between stimuli detected 50% of the time.

Visual Perception

• Gestalt principles: Guiding how visual elements form meaningful wholes.
• Proximity: Close objects grouped together.
• Similarity: Similar objects grouped together.
• Closure: Filling gaps in incomplete figures.
• Continuity: Perceiving smooth, continuous patterns.
• Figure-ground: Differentiating objects from their background.
• Depth perception: Perceiving the distance of objects.
• Binocular cues: Using both eyes for depth; retinal disparity (different images per eye) and convergence (eyes turning inward).
• Monocular cues: Using one eye for depth; linear perspective, texture gradient, interposition, relative size, relative height.
• Perceptual constancies: Perceiving objects as stable despite sensory changes.
• Size constancy: Maintaining perceived size despite retinal image changes.
• Shape constancy: Maintaining perceived shape despite retinal image changes.
• Brightness/color constancy: Perceiving constant brightness and color despite lighting changes.
• Location constancy: Maintaining perceived location despite body movement.

Auditory Perception

• Frequency: Determines pitch (measured in Hertz).
• Amplitude: Determines loudness (measured in decibels).
• Timbre: Determines quality (e.g., the difference between a flute and a violin).
• Sound localization: Identifying the location of a sound source.

Perceptual Illusions

• Müller-Lyer illusion: Lines with inward/outward arrowheads appear different lengths.
• Ponzo illusion: Identical lines in converging perspective appear different sizes.
• Other illusions: Show how context, expectation, and interpretation influence perception.

Factors Affecting Perception

• Motivation: Needs and desires influence what is perceived.
• Emotion: Emotional state affects perceptions.
• Culture: Cultural experiences shape interpretations.
• Individual differences: Personal experiences affect perception.
• Attention: Selective focus on specific stimuli.

Research Methods

• Experiments: Investigate perception by manipulating stimuli and measuring responses.
• Case studies: Understand unusual perceptual cases (e.g., disorders).
• Observation: Observe behavior in various situations to understand stimulus responses.