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Sensation & Perception

Sensation - our sensory receptors receive info from stimuli in the environment

Perception - our brains organizing and interpreting sensory info, gives us our ability to recognize, categorize, and understand

  • Bottom-up processing - makes sense of the information (new experiences)

    • sensory receptors → brain (younger in life)

  • Top-down processing - our brains construct perceptions based on our previous experiences and expectations (known experiences)

    • brain → sensory receptors (older in life)

Selective Inattention:

  • Change blindness - failure to notice changes in the environment

  • Inattentional blindness - we fail to see easily visible objects when our attention is directed to something else

Perceptual Set - pre-conceived way of interpreting a stimulus that is usually culturally or socially reinforced

  • eg. sensor bleeps

Structure and Functions of the Eye

Properties of Light:

  • Wavelength - determines the color/hue we see (distance between light wave peaks)

    • short = more blue-ish colors; long = more red-ish colors

  • Intensity of light waves (aka amplitude) determines the brightness of the colors we see

    • low intensity = dull colors; high intensity = bright colors

The Eye:

  • Cornea - the outer layer that protects the eye, also bends light waves in order to start focusing them

  • Pupil - the center of the eye-opening, it expands and contracts due to the action of the iris (colored muscle around the pupil)

  • Lens - lies behind the pupil, focuses the incoming light rays onto the retina through accommodation (changing shape in order to focus the object clearly)

  • Retina - the inner surface of the eye, highly sensitive to light; contains rods, cones, and neurons; the images focus on it are upside down

    • Rods - receptor cells that detect white, black, and grey

      • great at seeing in low light; poor at seeing color and detail

    • Cones - receptor cells that detect color

      • poor at seeing in. low light; great at seeing color and detail

    • Bipolar cells - activate in response to the rods and cones being stimulated

    • Ganglion cells - neurons that converge to form the optic nerve, which leaves the back of the eye and goes to the brain

  • Fovea - the point on the retina where images are focused; the cones cluster around it; the most sensitive area

  • Blind spot - no rods or cones where the optic nerve leaves the eye causing a blind spot in our vision

Labeled Eye Diagram

Visual Organization and Interpretation

Visual Organization:

  • Gestalt - an organized whole; gestalt psychologists emphasize our tendency to integrate pieces of info into meaningful wholes

  • Figure-ground - the organization of the visual field into objects that stand out from their surroundings

  • Grouping - the perceptual tendency to organize stimuli into coherent groups

  • Depth perception - the ability to see objects in 3D although the images that strike the images are 2D

  • Visual Cliff - a laboratory device for testing depth perception in infants and young animals

  • Binocular Cues - depth cues, such as retinal disparity

    • depend on the use of both eyes

  • Retinal Disparity - a binocular cue for perceiving depth

  • Monocular Cues - depth cues, such as interposition and linear perspective

    • available to either eye alone

  • Phi phenomenon - an illusion of movement created when 2 or more adjacent lights blink on and off in quick succession

  • Perceptual constancy - perceiving objects as unchanging even as illumination and retinal images change

  • Color constancy - perceiving familiar objects as having consistent color even if changing illumination alters the wavelength reflected by the object

Visual Interpretation:

  • Perceptual adaptation - in vision, the ability to adjust to an artificially displaced or even inverted visual field

The Other Senses

Touch

  • 4 basic skin sensations: pressure, warmth, cold, and pain

  • Pain is dependent on genes, physiology, experience, attention, surrounding culture, and sex

    • Nociceptors - sensory receptors that detect hurtful temperatures, pressures, and chemicals

    • Gate-control theory - that the spinal cord contains a neurological gate that blocks pain signals or allows them to passion onto the brain

    • Phantom limb sensation - when it misinterprets the spontaneous central nervous system activity that occurs in absence of normal sensory input

Taste

  • 4 basic tastes: sweet (energy), salty (sodium), sour (toxic?), bitter (poison?), and umami (proteins)

Smell

  • we can recognize long-forgotten odors and their associated memory

Body Position & Movement

  • kinesthesia - your sense of the position and movement of your body parts

  • vestibular sense - the sense of body movement and position including the sense of balance

Sensory Interaction - the principle that one sense may influence another

  • eg. physical warmth → social warmth

  • embodied cognition - the influence of bodily sensations, gestures, and other states on cognitive preferences and judgments

Hearing

Sound Waves: (sound is measured in decibels)

  • Audition - the sense or act of hearing

  • Amplitude - determines the loudness

  • Frequency - determines pitch; the number of complete wavelengths that pass a point in a given time

  • Pitch - a tone’s experienced highness or lowness

The Ear

  • Middle ear - the chamber between the eardrum and cochlea containing three bones (hammer, anvil, stirrup) that concentrate the vibrations of the eardrum on the cochlea’s oval window

  • Cochlea - a coiled, bony fluid-filled tube in the inner ear; sound waves travel through here triggering nerve impulses

  • Inner ear - the innermost part of the ear; contains the cochlea, semicircular canals, and vestibular sacs

  • Hearing loss:

    • Sensorineural hearing loss - caused by damage to the mechanical system that conducts sound waves to the cochlea

    • Conduction hearing loss - caused by damage to the mechanical system that conducts sound waves to the cochlea

  • Cochlear implant - a device for converting sounds into electrical signals and stimulating the auditory nerve through electrodes threaded in the cochlea

  • Place theory - the theory that links the pitch we hear with the place where the cochlea’s membrane is stimulated

  • Frequency theory - the theory that the rate of nerve impulses traveling up the auditory nerve matches the frequency of the tone

  • Absolute threshold - how much of a stimulus do we need to detect it 50% of the time

    • eg. concert 110 dB, talking 50 dB, >100 dB is likely to cause hearing damage

  • Outer ear - channels sound waves to the eardrum

  • Basilar membrane - moves caused by cochlea vibrations; covered with hair cells

  • Auditory (cochlear) nerve - axons in the inner ear send auditory signals to the temporal lobe

Perception of loudness:

  • louder sounds activate more hair cells

  • people with hearing loss often lose their sensitivity to soft sounds but will respond to loud sounds

  • instead of making everything louder, hearing aids compress sound (bring soft sounds up to the level of louder sounds and smooths out the changes in loudness)

Visual Processing

Feature detection

  • feature detectors - specialized neurons in the visual cortex, recognize/respond to specific features of a stimulus (lines, angles, edges, etc)

    • pass info to other brain areas that recognize/process the more complex features

    • our brains have a visual encyclopedia in which specialized cells fire in response to a very particular type of stimulus

Parallel processing - the brain’s natural processing of vision

  • we simultaneously process many different aspects of a stimulus

    • damage to parts of our visual network can disrupt this allowing some processing to happen but stopping others

  • blindsight - a phenomenon when a person is critically blind but can perceive motion

Color vision

  • Young-Helmholtz Trichromatic theory - the cones are sensitive to either red, green, or blue and combinations of these allow us to see color

    • people with color blindness may have monochromatic or dichromatic vision

  • Opponent-Process theory - says we have three opponent color pairs

    • red/green, yellow/blue, black/white

    • color vision comes from neurons being turned on or off by these colors

Perceptual constancy - when our brains perceive objects as having consistency (form, color) even when visual input differs

  • Color constancy - we perceive objects (especially familiar ones) as having consistent color, even if conditions alter the wavelength being reflected by the object

  • our vision is also good at shape and size constancies

McGurk effect - when our sense of vision and hearing conflict with each other, vision wins

RM

Sensation & Perception

Sensation - our sensory receptors receive info from stimuli in the environment

Perception - our brains organizing and interpreting sensory info, gives us our ability to recognize, categorize, and understand

  • Bottom-up processing - makes sense of the information (new experiences)

    • sensory receptors → brain (younger in life)

  • Top-down processing - our brains construct perceptions based on our previous experiences and expectations (known experiences)

    • brain → sensory receptors (older in life)

Selective Inattention:

  • Change blindness - failure to notice changes in the environment

  • Inattentional blindness - we fail to see easily visible objects when our attention is directed to something else

Perceptual Set - pre-conceived way of interpreting a stimulus that is usually culturally or socially reinforced

  • eg. sensor bleeps

Structure and Functions of the Eye

Properties of Light:

  • Wavelength - determines the color/hue we see (distance between light wave peaks)

    • short = more blue-ish colors; long = more red-ish colors

  • Intensity of light waves (aka amplitude) determines the brightness of the colors we see

    • low intensity = dull colors; high intensity = bright colors

The Eye:

  • Cornea - the outer layer that protects the eye, also bends light waves in order to start focusing them

  • Pupil - the center of the eye-opening, it expands and contracts due to the action of the iris (colored muscle around the pupil)

  • Lens - lies behind the pupil, focuses the incoming light rays onto the retina through accommodation (changing shape in order to focus the object clearly)

  • Retina - the inner surface of the eye, highly sensitive to light; contains rods, cones, and neurons; the images focus on it are upside down

    • Rods - receptor cells that detect white, black, and grey

      • great at seeing in low light; poor at seeing color and detail

    • Cones - receptor cells that detect color

      • poor at seeing in. low light; great at seeing color and detail

    • Bipolar cells - activate in response to the rods and cones being stimulated

    • Ganglion cells - neurons that converge to form the optic nerve, which leaves the back of the eye and goes to the brain

  • Fovea - the point on the retina where images are focused; the cones cluster around it; the most sensitive area

  • Blind spot - no rods or cones where the optic nerve leaves the eye causing a blind spot in our vision

Labeled Eye Diagram

Visual Organization and Interpretation

Visual Organization:

  • Gestalt - an organized whole; gestalt psychologists emphasize our tendency to integrate pieces of info into meaningful wholes

  • Figure-ground - the organization of the visual field into objects that stand out from their surroundings

  • Grouping - the perceptual tendency to organize stimuli into coherent groups

  • Depth perception - the ability to see objects in 3D although the images that strike the images are 2D

  • Visual Cliff - a laboratory device for testing depth perception in infants and young animals

  • Binocular Cues - depth cues, such as retinal disparity

    • depend on the use of both eyes

  • Retinal Disparity - a binocular cue for perceiving depth

  • Monocular Cues - depth cues, such as interposition and linear perspective

    • available to either eye alone

  • Phi phenomenon - an illusion of movement created when 2 or more adjacent lights blink on and off in quick succession

  • Perceptual constancy - perceiving objects as unchanging even as illumination and retinal images change

  • Color constancy - perceiving familiar objects as having consistent color even if changing illumination alters the wavelength reflected by the object

Visual Interpretation:

  • Perceptual adaptation - in vision, the ability to adjust to an artificially displaced or even inverted visual field

The Other Senses

Touch

  • 4 basic skin sensations: pressure, warmth, cold, and pain

  • Pain is dependent on genes, physiology, experience, attention, surrounding culture, and sex

    • Nociceptors - sensory receptors that detect hurtful temperatures, pressures, and chemicals

    • Gate-control theory - that the spinal cord contains a neurological gate that blocks pain signals or allows them to passion onto the brain

    • Phantom limb sensation - when it misinterprets the spontaneous central nervous system activity that occurs in absence of normal sensory input

Taste

  • 4 basic tastes: sweet (energy), salty (sodium), sour (toxic?), bitter (poison?), and umami (proteins)

Smell

  • we can recognize long-forgotten odors and their associated memory

Body Position & Movement

  • kinesthesia - your sense of the position and movement of your body parts

  • vestibular sense - the sense of body movement and position including the sense of balance

Sensory Interaction - the principle that one sense may influence another

  • eg. physical warmth → social warmth

  • embodied cognition - the influence of bodily sensations, gestures, and other states on cognitive preferences and judgments

Hearing

Sound Waves: (sound is measured in decibels)

  • Audition - the sense or act of hearing

  • Amplitude - determines the loudness

  • Frequency - determines pitch; the number of complete wavelengths that pass a point in a given time

  • Pitch - a tone’s experienced highness or lowness

The Ear

  • Middle ear - the chamber between the eardrum and cochlea containing three bones (hammer, anvil, stirrup) that concentrate the vibrations of the eardrum on the cochlea’s oval window

  • Cochlea - a coiled, bony fluid-filled tube in the inner ear; sound waves travel through here triggering nerve impulses

  • Inner ear - the innermost part of the ear; contains the cochlea, semicircular canals, and vestibular sacs

  • Hearing loss:

    • Sensorineural hearing loss - caused by damage to the mechanical system that conducts sound waves to the cochlea

    • Conduction hearing loss - caused by damage to the mechanical system that conducts sound waves to the cochlea

  • Cochlear implant - a device for converting sounds into electrical signals and stimulating the auditory nerve through electrodes threaded in the cochlea

  • Place theory - the theory that links the pitch we hear with the place where the cochlea’s membrane is stimulated

  • Frequency theory - the theory that the rate of nerve impulses traveling up the auditory nerve matches the frequency of the tone

  • Absolute threshold - how much of a stimulus do we need to detect it 50% of the time

    • eg. concert 110 dB, talking 50 dB, >100 dB is likely to cause hearing damage

  • Outer ear - channels sound waves to the eardrum

  • Basilar membrane - moves caused by cochlea vibrations; covered with hair cells

  • Auditory (cochlear) nerve - axons in the inner ear send auditory signals to the temporal lobe

Perception of loudness:

  • louder sounds activate more hair cells

  • people with hearing loss often lose their sensitivity to soft sounds but will respond to loud sounds

  • instead of making everything louder, hearing aids compress sound (bring soft sounds up to the level of louder sounds and smooths out the changes in loudness)

Visual Processing

Feature detection

  • feature detectors - specialized neurons in the visual cortex, recognize/respond to specific features of a stimulus (lines, angles, edges, etc)

    • pass info to other brain areas that recognize/process the more complex features

    • our brains have a visual encyclopedia in which specialized cells fire in response to a very particular type of stimulus

Parallel processing - the brain’s natural processing of vision

  • we simultaneously process many different aspects of a stimulus

    • damage to parts of our visual network can disrupt this allowing some processing to happen but stopping others

  • blindsight - a phenomenon when a person is critically blind but can perceive motion

Color vision

  • Young-Helmholtz Trichromatic theory - the cones are sensitive to either red, green, or blue and combinations of these allow us to see color

    • people with color blindness may have monochromatic or dichromatic vision

  • Opponent-Process theory - says we have three opponent color pairs

    • red/green, yellow/blue, black/white

    • color vision comes from neurons being turned on or off by these colors

Perceptual constancy - when our brains perceive objects as having consistency (form, color) even when visual input differs

  • Color constancy - we perceive objects (especially familiar ones) as having consistent color, even if conditions alter the wavelength being reflected by the object

  • our vision is also good at shape and size constancies

McGurk effect - when our sense of vision and hearing conflict with each other, vision wins

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