Rathus_PSYCH_7e_PPT_CH03

Chapter 3: Sensation and Perception

Icebreaker Discussion

• Explore beliefs about extrasensory perception (ESP) and intuition.

Chapter Objectives

• Sensation vs. Perception: Understand definitions and differences.

• Eye Anatomy: Learn parts of the eye, properties of light, and color vision theories.

• Visual Perception: Describe how visual perceptions are organized.

• Ear Anatomy: Identify parts of the ear and how hearing functions.

• Chemical & Skin Senses: Describe functioning of these senses, kinesthesis, and vestibular sense.

• Skepticism on ESP: Understand psychological perspectives on ESP.

Sensation and Perception Overview

Sensation

• Definition: Stimulation of sensory receptors in sense organs; transmission to CNS.

Perception

• Definition: Active organization and interpretation of sensory information.

Absolute Threshold

• Definition: Weakest level of stimulus detected 50% of the time.

• Sensitivity Varies: Some individuals have heightened sensitivity.

Subliminal Stimulation

• Definition: Sensory stimulation below absolute threshold.

• Types:

  • Visual stimuli processed when flashed briefly.

  • Auditory stimuli can be played at inaudible volumes or backwards.

Difference Threshold

• Definition: Minimum difference in magnitude necessary to distinguish stimuli 50% of the time.

• Weber's Constant: Fraction indicating difference threshold for energy intensity differences.

• Just Noticeable Difference (JND): Minimum difference detectable.

Signal-Detection Theory

• Interaction of Factors: Perception based on physical, biological, and psychological factors.

• Sensory Adaptation: Adjustments to stimuli.

  • Positive Adaptation: Increased sensitivity to low magnitude stimuli.

  • Negative Adaptation: Decreased sensitivity to stimuli of consistent intensity.

Vision: The Eye and Light

Light

• Electromagnetic Spectrum: Humans perceive a limited range; wavelength affects hue.

Anatomy of the Eye

• Cornea: Transparent protective covering.

• Iris: Colorful muscle controlling pupil size.

• Pupil: Opening affected by light and emotional response.

• Lens: Adjusts focus, projecting images onto the retina.

Rods and Cones

• Rods: Responsible for black and white vision; sensitive in dim light.

• Cones: Responsible for color vision, densely packed in the fovea.

• Visual Acuity: Linked to eye shape; near/farsightedness & presbyopia.

Color Vision

• Definitions: Hue, value, saturation affect color perception.

• Color Wheel: Classifies colors as warm (yellow-red) or cool (green-blue).

• Afterimage: Perception of complementary color after original color is removed.

Theories of Color Vision

• Trichromatic Theory: Three cones for red, green, blue; creates all colors through mixture.

• Opponent-Process Theory: Color receptors for pairs (red-green, blue-yellow), sensitive to brightness differences.

Color Blindness

• Trichromats: Have normal color vision.

• Monochromats: Totally color-blind; only perceive lightness.

• Dichromats: Partial color blindness; discriminate between two colors.

Visual Perception

Perceptual Organization

• Closure: Perceiving broken figures as whole.

• Figure-Ground Perception: Differentiating objects from their background.

Gestalt Rules

• Proximity, Similarity, Continuity, Common Fate: Principles of organizing visual elements into patterns.

Processing Information

• Top-Down Processing: Contextual knowledge influences perception.

• Bottom-Up Processing: Starting with components to build a complete image.

Depth Perception

• Monocular Cues: Depth perception using one eye (e.g., perspective, size, shadow).

• Binocular Cues: Involving both eyes (e.g., retinal disparity, convergence).

Perceptual Constancies

• Stability through Experience: Perceptions of size, color, brightness, shape remain stable across variations.

Hearing: Sound Perception

Pitch and Loudness

• Pitch: Frequency of sound measured in Hertz (Hz); higher frequency equals higher pitch.

• Loudness: Related to amplitude of sound waves, measured in decibels (dB).

Anatomy of the Ear

• Outer Ear: Funnels sound waves.

• Middle Ear: Amplifies sound; contains eardrum and tiny bones.

• Inner Ear: Cochlea converts vibrations into neural impulses sent to the brain.

Perception of Sound

• Loudness & Frequency Relationship: More neurons firing leads to louder perceived sounds; pitch sensed via place, frequency, and volley theories.

Deafness Types

• Conductive Deafness: Middle ear damage; hearing aids may help.

• Sensorineural Deafness: Inner ear/auditory nerve damage; cochlear implants can aid but won’t fully restore function.

Other Senses

Chemical Senses: Smell and Taste

• Smell: Involves olfactory receptors; significant for detecting flavor.

• Taste: Taste cells on taste buds perceive basic tastes (sweet, sour, salty, bitter, umami).

Skin Senses

• Touch, Pressure, Temperature, Pain: Different receptors reflect sensations; varies among body areas.

• Phantom Limb Pain: Pain in amputated limbs due to brain signals.

Kinesthesis and Vestibular Sense

• Kinesthesis: Awareness of body position and movement.

• Vestibular Sense: Balance and position related to gravity.

Extrasensory Perception (ESP)

ESP Research

• Joseph Banks Rhine: Proposed ESP through clairvoyance studies; Zener cards experiment.

• Types of ESP: Telepathy studied through guessing games; misunderstanding of correct guess probabilities leads to skepticism.

Skepticism Around ESP

• Research Integrity Issues: Issues like file-drawer problem may distort perceived results.

Self-Assessment

• Recognize major senses and how they process information.

• Understand failure reasons in sensory processes and phenomena like ESP.

Summary

• Differentiate between sensation and perception; comprehend sensory anatomy and processes; acknowledge skepticism on ESP.