Chapter 6 SENSATION AND PERCEPTION

Chapter Overview

  • Module 18: Basic Concepts of Sensation and Perception

  • Module 19: Vision: Sensory and Perceptual Processing

  • Module 20: Hearing, Skin, Chemical, and Body Senses

Module 18: Basic Concepts of Sensation and Perception

Sensation and Perception

  • Sensation: Process by which sensory receptors and nervous system receive and represent stimulus energies from the environment.

  • Sensory Receptors: Sensory nerve endings that respond to stimuli.

  • Perception: Process of organizing and interpreting sensory information, enabling recognition of meaningful objects and events.

Processing Sensations and Perceptions

  • Bottom-up Processing: Analysis that begins with sensory receptors and works up to the brain’s integration of sensory information.

  • Top-down Processing: Information processing guided by higher-level mental processes, influenced by experience and expectations.

Steps Basic to All Sensory Systems

  1. Receive sensory stimulation using specialized receptor cells.

  2. Transform that stimulation into neural impulses.

  3. Deliver the neural information to our brain.

Transduction

  • Transduction: Conversion of one form of energy into another, specifically the transformation of stimulus energies (sights, sounds, smells) into neural impulses.

  • Psychophysics: Study of relationships between physical energy and its effects on psychological experiences.

Thresholds

  • Absolute Threshold: Minimum stimulus energy needed to detect a particular stimulus 50% of the time.

  • Subliminal: Input below the absolute threshold for conscious awareness.

  • Signal Detection Theory: Predicts how and when faint stimuli will be detected amid background noise.

  • Difference Threshold (Just Noticeable Difference): Minimum difference a person can detect between two stimuli; increases with stimulus size (Weber’s Law).

Subliminal Stimulation

  • Subliminal sensations involve stimuli so weak they are not consciously noticed. Priming is used to activate unconscious associations, but the effects of subliminal persuasion are fleeting.

Sensory Adaptation

  • Sensory Adaptation: Diminished sensitivity due to constant stimulation which helps in focusing on informative changes in the environment.

Perceptual Set

  • Perceptual Set: Mental predisposition to perceive one thing and not another, influenced by schemas organized from experience. Cultural context can also determine perceptual set.

Module 19: Vision—Sensory and Perceptual Processing

Key Concepts in Vision

  • Wavelength: Distance from one peak of light/sound wave to the next.

  • Hue: Dimension of color determined by wavelength, known as color names (e.g. blue, green).

  • Intensity: Amount of energy in a light/sound wave, affects perceived brightness and loudness.

Anatomy of the Eye

  • Retina: Light-sensitive inner surface containing receptor rods and cones.

  • Accommodation: Process of changing lens shape to focus on near or far objects.

  • Rods and Cones: Rods detect black, white, gray; cones detect fine detail and color (focused in well-lit conditions).

Information Processing in Vision

  • Pathway: Light is transduced into neural signals which travel via optic nerve to the brain.

  • Feature Detection: Processing specific visual features (edges, lines, angles) in specific cortical areas.

  • Facial Recognition: Managed by the fusiform face area in the temporal lobe.

  • Parallel Processing: Simultaneous processing of multiple aspects of a stimulus.

Perceptual Organization

  • Gestalt Principles: Organizing sensations into meaningful wholes through concepts like figure-ground relationships and grouping principles (proximity, continuity, closure).

  • Depth Perception: Ability to see three-dimensional space and judge distance, evidenced from birth.

Cues for Depth Perception

  • Binocular Cues: Depend on the use of both eyes (e.g., retinal disparity).

  • Monocular Cues: Depth cues available to either eye alone (e.g., interposition, linear perspective).

Constancy in Perception

  • Perceptual Constancy: Perceiving objects as unchanging despite changes in illumination and retinal images, includes color consistency, shape, and size.

Module 20: Hearing, Skin, Chemical, and Body Senses

Hearing

  • Sound Waves: Created by compressing and expanding air molecules.

  • Sound Intensity: Measured in decibels; relative perception (loudness) can be compared using decibel scale.

  • Hearing Loss: Can result from damage to cochlea’s hair cells or auditory nerve.

Touch and Pain

  • Touch: Involves four distinct skin senses: pressure, warmth, cold, and pain.

  • Pain: Affected by biological, psychological, and social-cultural factors influenced by focus, memories, and social situations.

The Chemical Senses

  • Taste: Basic sensations—sweet, sour, salty, bitter, umami—communicate essential information for survival. Influenced by culture and learning.

  • Smell: Linked to memory, processed by olfactory cortex, relying on the interaction of multiple receptors.

Body Position and Movement

  • Kinesthesia: System for sensing the position and movement of body parts.

  • Vestibular Sense: Sense of balance and body orientation.

Sensory Interaction

  • Interaction between senses, e.g., smell influencing taste perception.

  • Embodied Cognition: Bodily sensations influencing cognitive preferences and judgments.

Extrasensory Perception (ESP)

  • Claims include telepathy, clairvoyance, precognition; skepticism about research methods remains prevalent.