Study Notes on Sensation and Perception from Psychology in Everyday Life

Copyright Information

• Copyright © 2022 by Macmillan Learning. All rights reserved
• Source: Psychology in Everyday Life David G. Myers • C. Nathan DeWall | Sixth Edition

Chapter Overview

• Main topics covered:
  • Basic Concepts of Sensation and Perception
  • Vision
  • The Nonvisual Senses
  • Sensory Interaction
  • Perception Without Sensation

Basic Concepts of Sensation and Perception

• Sensation

  • Definition: Process by which the sensory receptors and nervous system receive and represent stimulus energies from our environment.
  • Sensory Receptors: Sensory nerve endings that respond to stimuli.

• Perception

  • Definition: Process by which the brain organizes and interprets sensory information, transforming it into meaningful objects and events.

• Bottom-up Processing

  • Definition: Information processing that begins with the sensory receptors and works up to the brain’s integration of sensory information.
  • Example: Detection of lines, angles, and colors.

• Top-down Processing

  • Definition: Information processing guided by higher-level mental processes, drawing on one’s experiences and expectations.
  • Implication: Interpretation of what senses detect can be influenced by prior knowledge and context.

• Transduction

  • Description: The steps that convert outside energy into a form usable by the brain.
  • Receive sensory stimulation.
  • Transform the stimulation into neural impulses.
  • Deliver the neural information to the brain.

• Absolute Threshold

  • Definition: The minimum stimulus energy needed to detect a particular stimulus 50% of the time.

• Subliminal Stimulation

  • Definition: Stimulation that is so weak that people do not consciously notice it.
  • Effects: Individuals can be influenced by subliminal stimuli without conscious awareness.
  • Priming: Technique where researchers activate unconscious associations.

• Difference Threshold (Just Noticeable Difference - jnd)

  • Definition: Minimum difference between two stimuli required for detection 50% of the time.

• Weber’s Law

  • Definition: Two stimuli must differ by a constant minimum percentage, rather than a constant amount.
  • Note: Exact percentage needed for differentiation varies based on stimulus.

• Sensory Adaptation

  • Definition: Reduced sensitivity in response to constant stimulation, which heightens alertness to novelty.
  • Implication: Allows individuals to focus on informative changes in the environment and avoid distractions from constant stimuli.
  • Example: The phenomenon “Now you see it, now you don’t” demonstrated with a projector on contact lenses revealing adaptation.

• Perceptual Set

  • Definition: Mental predisposition to perceive one thing over another.
  • Experimental Example: Participants shown different images may report different perceptions based on prior viewing context.

• Context, Motivation, and Emotion

  • Description: Context shapes perceptions and interpretations, including cultural influence.
  • Motivation drives goals but can introduce bias in interpreting stimuli.
  • Emotions can influence perceptual outcomes by shaping views of reality.

Vision

Basic Concepts

• Light Energy

  • Definition: Energy from the environment that is transformed into vision.
  • Wavelength: Distance from the peak of one light wave to the peak of the next, influencing hue.
  • Hue: Dimension of color determined by the wavelength of light.
  • Intensity: Amount of energy in a light wave, affecting perception of brightness or loudness.
  • Determined by the wave’s amplitude or height.

• Visible Wavelengths

  • Extension: From the shorter waves of blue-violet light to the longer waves of red light.

The Eye's Structure and Function

• Iris

  • Description: Doughnut-shaped muscle ring that controls pupil size, revealing thoughts and emotions.

• Cornea

  • Function: Light enters through the cornea, passing through the pupil and hitting the transparent lens.

• Lens

  • Function: Focuses light rays into an image on the retina, the multilayered lining on the back inner surface of the eye.

• Retina

  • Description: Light-sensitive back inner surface of the eye.
  • Components: Contains receptor cells (rods and cones), layers of neurons for processing visual information.
  • Optic Nerve: Carries neural impulses from the eye to the brain.
  • Blind Spot: Area where the optic nerve exits the eye, lacking receptor cells.

Eye-to-Brain Pathway

• Process involves:
  • Light striking the retina -> neural signals triggered in rods/cones -> activation of bipolar cells -> ganglion cells -> optic nerve formation -> relay through the thalamus -> arrival at the visual cortex in the occipital lobe.

Vision Receptors

• Cones (6 million)

  • Location: Center of the retina.
  • Function: High color sensitivity and detail sensitivity.

• Rods (120 million)

  • Location: Periphery of the retina.
  • Function: High sensitivity in dim light, lower color sensitivity and detail sensitivity.

Color Perception Theories

• Young-Helmholtz Trichromatic Theory

  • Description: Retina contains three types of color receptors (red, green, blue) which can stimulate combinations to create color perception.

• Opponent-Process Theory

  • Description: There are opposing retinal processes (red-green, yellow-blue, white-black) that enable color vision.

• Color Processing

  • Involves both trichromatic and opponent-processing theories in two stages via retinal cone responses and subsequent processing in the brain.

Feature Detection and Processing

• Feature Detectors

  • Definition: Nerve cells in the brain that respond to specific stimuli features such as shape, angles, or movement.
  • Result: Processes scene-specific information and contributes to complex pattern interpretations.

• Supercells

  • Description: Interactivity between feature detectors and supercells enables rapid analyses of visual data in real-time scenarios.

• Parallel Processing

  • Definition: Brain's method of processing multiple aspects of a scene simultaneously; crucial for visual perception.

Perceptual Organization

• Gestalt Psychology

  • Definition: Emphasizes the tendency of humans to integrate pieces of information into meaningful wholes.
  • Implication: The perception of a whole may exceed the sum of its parts, demonstrating that the brain actively filters and constructs perceptions from stimuli.

• Figure-Ground Relationship

  • Definition: Organization in the visual field, distinguishing objects (figures) from their backgrounds (ground).

• Grouping Principles

  • Three principles:
  • Proximity: Elements close together are more likely to be grouped together.
  • Continuity: We perceive smooth, continuous patterns rather than discontinuous ones.
  • Closure: We fill in gaps to create a complete, whole object.

Depth Perception

• Definition: Ability to see objects in three dimensions, even though images that strike the retina are two-dimensional.
• Importance: Allows for judgment of distance.
• Experimental Insight: Visual cliff experiment indicating depth perception development in infants.

Cues for Depth Perception

• Binocular Cues

  • Definition: Depth cues that rely on both eyes.
  • Convergence: Inward angle of the eyes indicates proximity to objects.
  • Retinal Disparity: The brain's calculation of distance using images from both eyes.

• Monocular Cues

  • Definition: Depth cues available to each eye independently.
  • Includes: Relative height, relative size, interposition, relative motion, linear perspective, light and shadow.

Motion Perception

• Explanation: The human brain infers motion based on object size and relative velocity.
  • General Assumption: Shrinking objects are perceived as moving away; enlarging objects as moving closer.
  • Note: Perception of motion can be distorted under certain conditions.

Perceptual Constancy

• Perceptual Constancy

  • Definition: Perceiving objects as unchanging, even as illumination and retinal images change.
  • Types: Color constancy, brightness constancy, shape constancy, and size constancy.

• Color Constancy

  • Description: Objects perceived to have consistent color despite changes in illumination.

• Size Constancy

  • Explanation: Objects perceived to have a constant size even when their distance changes.

Perceptual Interpretation

• Immanuel Kant's View

  • Assertion: Humans have an innate ability to process sensory information.

• John Locke's Perspective

  • Argument: Sensory perception is learned, linking object distance to size based on experience.

Sensory Restriction and Perception

• Insight: Critical periods for normal sensory and perceptual development are evident through studies on sensory deprivation in infants.
• Finding: Eye patches or other sensory restrictions do not cause long-term damage in terms of perceptual capabilities.

Perceptual Adaptation

• Definition: Ability to adjust to changed sensory input, including inverted visual fields.
• Conclusion: Experience and early nurture significantly shape perceptual development and maintained pathways in the brain.

Hearing (Audition)

• Definition of Audition
  • Sense or act of hearing, crucial for adaptation, survival, and interpersonal relationships.

Sound Waves

• Description: Sound waves vary in shape and are measured in decibels.
• Creation: Produced by moving air molecules creating areas of compressed and expanded air.

Decoding Sound Waves

• Process: Sound waves strike the eardrum, causing vibrations that are transferred through tiny bones to the cochlea, resulting in hair cell activation and subsequent neural impulse transmission to the auditory cortex via the auditory nerve.

Hearing Loss

• Sensorineural Hearing Loss (Nerve Deafness)
  • Cause: Damage to hair cells in the cochlea or auditory nerves; cannot be reversed.
• Conduction Hearing Loss
  • Cause: Damage to the mechanical system conducting sound to the cochlea; less common.
• Prevalence in Teens
  • Statistics: One-third increase in hearing loss cases in teens since the 1990s, with boys more affected than girls.

Locating Sound

• Mechanism: The brain uses the time of arrival and intensity differences of sound waves between ears to compute direction.

Touch

• Definition of Touch
  • Composed of four distinct skin senses: pressure, warmth, cold, and pain.
• Other skin sensations are variations of these basic senses.

Pain

• Nature of Pain
  • Pain is a biopsychosocial phenomenon, influenced by biological, psychological, and social factors.
• Nociceptors
  • Sensory receptors that detect hurtful temperatures, pressure, or chemicals and produce perceptions of pain.
• Examples of Phantom Sensations: Phantom limb sensations, tinnitus, phantom tastes, and natural pain relief mechanisms like endorphins.

Psychological Influences on Pain

• Attention: Focused attention can amplify pain perception; memory of pain is often edited.

Social-Cultural Influences on Pain

• Pain perception varies significantly based on social context and cultural norms.
• Increased pain perception can occur in empathetic situations.

Controlling Pain

• Various treatments for controlling pain include psychological and physical therapies, acupuncture, and relaxation techniques.
• Placebos: Can dampen responses to painful stimuli through belief in effectiveness.

Senses Summary

Perception Without Sensation

• Extrasensory Perception (ESP)
  • Definition: The idea that perception can occur without sensory input, including claims of telepathy, clairvoyance, and precognition.
• Psychokinesis: Claim of mind's ability to influence physical matter.
  • Research Skepticism: Challenges exist in experimentally validating ESP claims due to lack of controlled reproducibility.
• Daryl Bem's Experiments: Suggested subjects could anticipate future events; criticisms arose regarding methodological flaws.