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Chapter 5 - Sensation and Perception

Getting Started

  • Sensation (Bottom-Up Processing) - “the process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment” (pg. 133)

  • Perception (Top-Down Processing) - “the process by which our brain organizes and interprets sensory information, transforming it into meaningful objects and events” (pg. 133)

  • Transduction - “the process of converting one form of energy into another that our brain can use” (pg. 132)

Psychophysics

  • An early research area in psychology

  • Psychophysics - the study of the relationship between physical stimulation and psychological experience

  • Absolute Threshold - “the minimum stimulus energy needed to detect a particular stimulus” (pg. 133)

    • 50% of a group detects the stimulus

  • Signal Detection - Individual absolute thresholds vary with our psychological state (expectations, motivations, and alertness)

Difference Threshold

  • Difference Threshold a.k.a., just noticeable difference (jnd) - The minimum difference in stimulation that a person can detect 50% of the time

  • Weber’s Law - Difference thresholds increase in proportion to the size of the stimulus

Eye - Rods and Cones

  • Color-sensitive cones are concentrated around the fovea, while the color-blind rods dominate the periphery of the retina.

  • Brain uses parallel processing of sensory information

Perceptual Organization

Depth Perception

  • Gestalt - German for “form”; “whole”

    • “The whole may exceed the sum of its parts”

    • All the parts (what your senses give you) form a whole object in your brain

      • Just the colors of a bird can’t help you identify it (blue, green, brown could be hummingbird or peafowl), but all parts put together can help you identify the species

  • Depth Perception - Visual cliff

  • Need both eyes to accurately estimate depth using retinal disparity

    • Retinal disparity - objects not being in the same place when off-center in front of you and looked at by one eye, helping you more accurately perceive distance

  • Two different ways to perceive depth - binocular cues and monocular cues

    • Binocular cues - use both eyes to perceive depth of objects close to us

    • Monocular cues - use one eye to perceive depth of objects far from us

Motion Detection

  • Another basic aspect of vision

  • Provides an adaptive advantage

  • Troxler Effect - Objects in the peripheral retina disappear under conditions of steady, unmoving stimulation but are revitalized by movement in the periphery

Perceptual Constancy

  • Perceptual Constancy - “Perceiving objects as unchanging… even as illumination and retinal images change” (pg. 149)

    • Vision perceiving objects shrinking as they get further away BUT knowing they are NOT actually shrinking

Hearing

  • The perceived direction of a sound is related to differences in the time at which the sound is received by each ear

Touch

Mix of Four Distinct and Basic Senses:

  1. Pressure

  2. Warmth

  3. Cold

  4. Pain

Combination Examples:

Cold + Warm = Hot

Cold + Pressure = Wetness

  • Touch localization - Noticing where on your body you experience touch

  • Touch localization is partly dependent on distance of the body part that is touched to the brain

Body Position and Movement

  • Kinesthesia - “System for sensing the position and movement of individuals body parts” (pg. 159)

  • Vestibular Sense - “Sense of body movement and position, including the sense of balance” (pg. 159)

    • i.e., equilibrium

Functions of vestibular system (inner ear):

  1. Maintains balance and upright posture

  2. Controls eye position as we move our heads when viewing objects

  • Continuous Movement

    • Currents in the semicircular canals

      • Compensatory eye movements

  • Nystagmus - Reflex movement evoked by vestibular stimulation

Vision & Equilibrium

  • Our ability to maintain balance depends on visual cues

  • Related to a cognitive style:

  1. Field Dependence - Rely on visual cues

  2. Field Independence - Rely on vestibular cues

Hypnosis

Mesmer (Anton Mesmer)

Two Main Theories:

  1. Social Influence Theory - Hypnosis can be explained through other psychological experiences (Putting on an act as a good subject, even subconsciously)

  2. Dissociation Theory - Separating into parts of yourself (Believing when given the suggestion of something)

  • Dissociation - split in consciousness that allows some thoughts and behaviors to occur simultaneously with others

    • Hidden Observer - Part of your body still knows what’s going on

  • Hypnotic Susceptibility - person’s ability to become deeply hypnotized; suggestibility

What affects this:

  • Ability to become immersed in a role

  • Absorption - ability to become highly involved in sensory or imaginative sequences

  • Positive Attitude

  • Motivation - self motivated for hypnotism works best

  • Expectancy - skepticism makes it less likely to work

MS

Chapter 5 - Sensation and Perception

Getting Started

  • Sensation (Bottom-Up Processing) - “the process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment” (pg. 133)

  • Perception (Top-Down Processing) - “the process by which our brain organizes and interprets sensory information, transforming it into meaningful objects and events” (pg. 133)

  • Transduction - “the process of converting one form of energy into another that our brain can use” (pg. 132)

Psychophysics

  • An early research area in psychology

  • Psychophysics - the study of the relationship between physical stimulation and psychological experience

  • Absolute Threshold - “the minimum stimulus energy needed to detect a particular stimulus” (pg. 133)

    • 50% of a group detects the stimulus

  • Signal Detection - Individual absolute thresholds vary with our psychological state (expectations, motivations, and alertness)

Difference Threshold

  • Difference Threshold a.k.a., just noticeable difference (jnd) - The minimum difference in stimulation that a person can detect 50% of the time

  • Weber’s Law - Difference thresholds increase in proportion to the size of the stimulus

Eye - Rods and Cones

  • Color-sensitive cones are concentrated around the fovea, while the color-blind rods dominate the periphery of the retina.

  • Brain uses parallel processing of sensory information

Perceptual Organization

Depth Perception

  • Gestalt - German for “form”; “whole”

    • “The whole may exceed the sum of its parts”

    • All the parts (what your senses give you) form a whole object in your brain

      • Just the colors of a bird can’t help you identify it (blue, green, brown could be hummingbird or peafowl), but all parts put together can help you identify the species

  • Depth Perception - Visual cliff

  • Need both eyes to accurately estimate depth using retinal disparity

    • Retinal disparity - objects not being in the same place when off-center in front of you and looked at by one eye, helping you more accurately perceive distance

  • Two different ways to perceive depth - binocular cues and monocular cues

    • Binocular cues - use both eyes to perceive depth of objects close to us

    • Monocular cues - use one eye to perceive depth of objects far from us

Motion Detection

  • Another basic aspect of vision

  • Provides an adaptive advantage

  • Troxler Effect - Objects in the peripheral retina disappear under conditions of steady, unmoving stimulation but are revitalized by movement in the periphery

Perceptual Constancy

  • Perceptual Constancy - “Perceiving objects as unchanging… even as illumination and retinal images change” (pg. 149)

    • Vision perceiving objects shrinking as they get further away BUT knowing they are NOT actually shrinking

Hearing

  • The perceived direction of a sound is related to differences in the time at which the sound is received by each ear

Touch

Mix of Four Distinct and Basic Senses:

  1. Pressure

  2. Warmth

  3. Cold

  4. Pain

Combination Examples:

Cold + Warm = Hot

Cold + Pressure = Wetness

  • Touch localization - Noticing where on your body you experience touch

  • Touch localization is partly dependent on distance of the body part that is touched to the brain

Body Position and Movement

  • Kinesthesia - “System for sensing the position and movement of individuals body parts” (pg. 159)

  • Vestibular Sense - “Sense of body movement and position, including the sense of balance” (pg. 159)

    • i.e., equilibrium

Functions of vestibular system (inner ear):

  1. Maintains balance and upright posture

  2. Controls eye position as we move our heads when viewing objects

  • Continuous Movement

    • Currents in the semicircular canals

      • Compensatory eye movements

  • Nystagmus - Reflex movement evoked by vestibular stimulation

Vision & Equilibrium

  • Our ability to maintain balance depends on visual cues

  • Related to a cognitive style:

  1. Field Dependence - Rely on visual cues

  2. Field Independence - Rely on vestibular cues

Hypnosis

Mesmer (Anton Mesmer)

Two Main Theories:

  1. Social Influence Theory - Hypnosis can be explained through other psychological experiences (Putting on an act as a good subject, even subconsciously)

  2. Dissociation Theory - Separating into parts of yourself (Believing when given the suggestion of something)

  • Dissociation - split in consciousness that allows some thoughts and behaviors to occur simultaneously with others

    • Hidden Observer - Part of your body still knows what’s going on

  • Hypnotic Susceptibility - person’s ability to become deeply hypnotized; suggestibility

What affects this:

  • Ability to become immersed in a role

  • Absorption - ability to become highly involved in sensory or imaginative sequences

  • Positive Attitude

  • Motivation - self motivated for hypnotism works best

  • Expectancy - skepticism makes it less likely to work

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