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Chapter 5: Sensation and Perception

  • Sensation:  is the stimulus detection process by which our sense organs respond to and translate environmental stimuli into nerve impulses that are sent to the brain

  • Perception: making “sense” of what our senses tell us—is the active process of organizing this stimulus input and giving it meaning

Sensory Processes

  • Transduction:  is the process whereby the characteristics of a stimulus are converted into nerve impulses

  • Psychophysics: studies relations between the physical characteristics of stimuli and sensory capabilities

  • Absolute Threshold: the lowest intensity at which a stimulus can be detected 50 percent of the time

  • Decision Criterion: a standard of how certain they must be that a stimulus is present before they will say they detect it

  • Signal-Detection Theory: is concerned with the factors that influence sensory judgments

  • Difference Threshold (just noticeable difference(jnd)): is defined as the smallest difference between two stimuli that people can perceive 50 percent of the time

  • Weber’s law: states that the difference threshold or jnd is directly proportional to the magnitude of the stimulus with which the comparison is being made

  • Sensory adaptation: the diminishing sensitivity to an unchanging stimulus

Vision

  • Lens: an elastic structure that becomes thinner to focus on distant objects and thicker to focus on nearby objects

  • Retina: a multi-layered light-sensitive tissue at the rear of the fluid-filled eyeball.

  • Rods:  which function best in dim light, are primarily black-and-white brightness receptors

  • Cones: are color receptors, function best in bright illumination

  • Fovea: a small area in the center of the retina that contains no rods but many densely packed cones

  • Visual Acuity: ability to see fine detail

  • Photopigments: Rods and cones translate light waves into nerve impulses through the action of protein molecules

  • Dark Adaption: the progressive improvement in brightness sensitivity that occurs over time under conditions of low illumination

  • Young-Helmholtz trichromatic theory: there are three types of color receptors in the retina

  • Hering’s opponent-process Theory: proposed that each of the three cone types responds to two different wavelengths

  • Dual-Process Theory: combines the trichromatic and opponent-process theories to account for the color transduction process

  • Feature Detectors: fire selectively in response to visual stimuli that have specific characteristics

Audition

  • Frequency: the number of sound waves, or cycles, per second

  • Hertz(Hz): the technical measure of cycles per second; 1 hertz equals 1 cycle per second

  • Amplitude: refers to the vertical size of the sound waves—that is, the amount of compression and expansion of the molecules in the conducting medium

  • Cochlea: a coiled, snail-shaped tube about 3.5 centimeters (1.4 inches) in length that is filled with fluid and contains the Basilar Membrane

  • Basilar Membrane: a sheet of tissue that runs its length.

  • Organ of Corti: contains about 16,000 tiny hair cells that are the actual sound receptors

  • Frequency Theory of Pitch Perception: nerve impulses sent to the brain match the frequency of the sound wave

  • Place Theory of Pitch Perception: suggesting that the specific point in the cochlea where the fluid wave peaks and most strongly bends the hair cells serves as a frequency coding cue

  • Conduction Deafness:  involves problems with the mechanical system that transmits sound waves to the cochlea

  • Nerve Deafness: caused by damaged receptors within the inner ear or damage to the auditory nerve itself

Taste and Smell: the Chemical Senses

  • Gustation: the sense of taste

  • Olfaction: the sense of smell

  • Taste buds: chemical receptors concentrated along the tip, edges, and back surface of the tongue

  • Olfactory Bulb: a forebrain structure immediately above the nasal cavity

  • Pheromones: chemical signals found in natural body scents

    • Can affect human behavior in subtle ways

The Skin and Body Senses

  • Gate Control Theory: proposes that the experience of pain results from the opening and closing of gating mechanisms in the nervous systems

  • Kinesthesis: provides us with feedback about our muscles’ and joints’ positions and movements

  • Vestibular sense: the sense of body orientation or equilibrium

Perception: The Creation of Experience

  • Bottom-up Processing: the system takes in individual elements of the stimulus and then combines them into a unified perception

  • Top-Down Processing:  sensory information is interpreted in light of existing knowledge, concepts, ideas, and expectations

  • Inattentional Blindness: refers to the failure of unattended stimuli to register in consciousness

    • Backed up why you shouldn’t be on your phone while driving

  • Gestalt Theories:

    • Figure-Ground relations: tendency to organize stimuli into a central or foreground figure and a background

    • Gestalt Theory of Perceptual Organization: similarity, proximity, closure, and continuity

      • Examples include the duck/rabbit image, is it a vase or two people kissing, etc

  • Perceptual Schema: a mental representation or image containing the critical and distinctive features of a person, object, event, or other perceptual phenomena

  • Perceptual set: a readiness to perceive stimuli in a particular way

  • Perceptual Constancies: allow us to recognize familiar stimuli under varying conditions

Perception of Depth, Distance, and Movement

  • Monocular Depth Cues: which require only one eye

    • Cues include patterns of light and shadow, linear perspective, interposition, height, relative size, motion parallax.

  • Binocular Depth Cues: requires both eyes

    • Binocular Disparity: where each eye sees a slightly different image

    • Convergence: is produced by feedback from the muscles that turn your eyes inward to view a close object

  • Stroboscopic movement: illusory movement produced when a light is briefly flashed in darkness, and then, a few milliseconds later, another light is flashed nearby

  • Illusions: compelling but incorrect perceptions

  • Critical Periods: during which certain kinds of experiences must occur if perceptual abilities and the brain mechanisms that underlie them are to develop normally

Chapter 5: Sensation and Perception

  • Sensation:  is the stimulus detection process by which our sense organs respond to and translate environmental stimuli into nerve impulses that are sent to the brain

  • Perception: making “sense” of what our senses tell us—is the active process of organizing this stimulus input and giving it meaning

Sensory Processes

  • Transduction:  is the process whereby the characteristics of a stimulus are converted into nerve impulses

  • Psychophysics: studies relations between the physical characteristics of stimuli and sensory capabilities

  • Absolute Threshold: the lowest intensity at which a stimulus can be detected 50 percent of the time

  • Decision Criterion: a standard of how certain they must be that a stimulus is present before they will say they detect it

  • Signal-Detection Theory: is concerned with the factors that influence sensory judgments

  • Difference Threshold (just noticeable difference(jnd)): is defined as the smallest difference between two stimuli that people can perceive 50 percent of the time

  • Weber’s law: states that the difference threshold or jnd is directly proportional to the magnitude of the stimulus with which the comparison is being made

  • Sensory adaptation: the diminishing sensitivity to an unchanging stimulus

Vision

  • Lens: an elastic structure that becomes thinner to focus on distant objects and thicker to focus on nearby objects

  • Retina: a multi-layered light-sensitive tissue at the rear of the fluid-filled eyeball.

  • Rods:  which function best in dim light, are primarily black-and-white brightness receptors

  • Cones: are color receptors, function best in bright illumination

  • Fovea: a small area in the center of the retina that contains no rods but many densely packed cones

  • Visual Acuity: ability to see fine detail

  • Photopigments: Rods and cones translate light waves into nerve impulses through the action of protein molecules

  • Dark Adaption: the progressive improvement in brightness sensitivity that occurs over time under conditions of low illumination

  • Young-Helmholtz trichromatic theory: there are three types of color receptors in the retina

  • Hering’s opponent-process Theory: proposed that each of the three cone types responds to two different wavelengths

  • Dual-Process Theory: combines the trichromatic and opponent-process theories to account for the color transduction process

  • Feature Detectors: fire selectively in response to visual stimuli that have specific characteristics

Audition

  • Frequency: the number of sound waves, or cycles, per second

  • Hertz(Hz): the technical measure of cycles per second; 1 hertz equals 1 cycle per second

  • Amplitude: refers to the vertical size of the sound waves—that is, the amount of compression and expansion of the molecules in the conducting medium

  • Cochlea: a coiled, snail-shaped tube about 3.5 centimeters (1.4 inches) in length that is filled with fluid and contains the Basilar Membrane

  • Basilar Membrane: a sheet of tissue that runs its length.

  • Organ of Corti: contains about 16,000 tiny hair cells that are the actual sound receptors

  • Frequency Theory of Pitch Perception: nerve impulses sent to the brain match the frequency of the sound wave

  • Place Theory of Pitch Perception: suggesting that the specific point in the cochlea where the fluid wave peaks and most strongly bends the hair cells serves as a frequency coding cue

  • Conduction Deafness:  involves problems with the mechanical system that transmits sound waves to the cochlea

  • Nerve Deafness: caused by damaged receptors within the inner ear or damage to the auditory nerve itself

Taste and Smell: the Chemical Senses

  • Gustation: the sense of taste

  • Olfaction: the sense of smell

  • Taste buds: chemical receptors concentrated along the tip, edges, and back surface of the tongue

  • Olfactory Bulb: a forebrain structure immediately above the nasal cavity

  • Pheromones: chemical signals found in natural body scents

    • Can affect human behavior in subtle ways

The Skin and Body Senses

  • Gate Control Theory: proposes that the experience of pain results from the opening and closing of gating mechanisms in the nervous systems

  • Kinesthesis: provides us with feedback about our muscles’ and joints’ positions and movements

  • Vestibular sense: the sense of body orientation or equilibrium

Perception: The Creation of Experience

  • Bottom-up Processing: the system takes in individual elements of the stimulus and then combines them into a unified perception

  • Top-Down Processing:  sensory information is interpreted in light of existing knowledge, concepts, ideas, and expectations

  • Inattentional Blindness: refers to the failure of unattended stimuli to register in consciousness

    • Backed up why you shouldn’t be on your phone while driving

  • Gestalt Theories:

    • Figure-Ground relations: tendency to organize stimuli into a central or foreground figure and a background

    • Gestalt Theory of Perceptual Organization: similarity, proximity, closure, and continuity

      • Examples include the duck/rabbit image, is it a vase or two people kissing, etc

  • Perceptual Schema: a mental representation or image containing the critical and distinctive features of a person, object, event, or other perceptual phenomena

  • Perceptual set: a readiness to perceive stimuli in a particular way

  • Perceptual Constancies: allow us to recognize familiar stimuli under varying conditions

Perception of Depth, Distance, and Movement

  • Monocular Depth Cues: which require only one eye

    • Cues include patterns of light and shadow, linear perspective, interposition, height, relative size, motion parallax.

  • Binocular Depth Cues: requires both eyes

    • Binocular Disparity: where each eye sees a slightly different image

    • Convergence: is produced by feedback from the muscles that turn your eyes inward to view a close object

  • Stroboscopic movement: illusory movement produced when a light is briefly flashed in darkness, and then, a few milliseconds later, another light is flashed nearby

  • Illusions: compelling but incorrect perceptions

  • Critical Periods: during which certain kinds of experiences must occur if perceptual abilities and the brain mechanisms that underlie them are to develop normally

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