The body receives information through the five main senses. The Five Human Senses...
-
Upload
megan-edwards -
Category
Documents
-
view
227 -
download
0
Transcript of The body receives information through the five main senses. The Five Human Senses...
The body receives information through the five main senses.
The Five Human SensesHearing
Vision Taste
Smell
Touch
Sensation
a process by which our sensory receptors and nervous system receive and represent stimulus energy
Perception
a process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events
Sensation
Bottom-Up Processing
analysis that begins with the sense receptors and works up to the brain’s integration of sensory information
Top-Down Processing
information processing guided by higher-level mental processes
as when we construct perceptions drawing on our experience and expectations
Sensation
Our sensory and perceptual processes work together to help us sort out complex processes
How Many Wolves?
Psychophysics
study of the relationship between physical characteristics of stimuli and our psychological experience of them
Light- brightness
Sound- volume
Pressure- weight
Taste- sweetness
Sensation - Basic Principles
Absolute Threshold
minimum stimulation needed to detect a particular stimulus 50% of the time
Difference Threshold
minimum difference between two stimuli required for detection 50% of the time
just noticeable difference (JND)
Sensation - Threshold
An absolute threshold is the minimal amount of sensory stimulation needed for a sensation to occur.
Signal Detection Theory
predicts how and when we detect the presence of a faint stimulus (signal) amid background stimulation (noise)
assumes that there is no single absolute threshold
detection depends partly on person’s
experience
expectations
motivation
level of fatigue
Subliminal
When stimuli are below one’s absolute threshold for conscious awareness
0
25
50
75
100
Low Absolutethreshold
Medium
Intensity of stimulus
Percentageof correctdetections
Subliminal stimuli
Subliminal Messages
Subliminals?
Subliminals?
Weber’s Law- to perceive as different, two stimuli must differ by a constant minimum percentage
light intensity- 8%
weight- 2%
tone frequency- 0.3%
Sensory adaptation- diminished sensitivity as a consequence of constant stimulation
Sensation
Transduction
conversion of one form of energy to another
in sensation, transforming of stimulus energies into neural impulses
Wavelength
the distance from the peak of one wave to the peak of the next
Vision
Hue
dimension of color determined by wavelength of light
Intensity
amount of energy in a wave determined by amplitude
brightness
loudness
Vision
Short wavelength=high frequency(bluish colors, high-pitched sounds)
Long wavelength=low frequency(reddish colors, low-pitched sounds)
Great amplitude(bright colors, loud sounds)
Small amplitude(dull colors, soft sounds)
Vision-Physical
Light: The Visual Stimulus
Light can be described as both a particle and a wave
Wavelength of a light is the distance of one complete cycle of the wave
Visible light has wavelengths from about 400nm to 700nm
Wavelength of light is related to its perceived color
The spectrum of electromagnetic energy
Vision Cornea– the outer covering of the eye
Pupil- adjustable opening in the center of the eye
Vision Iris- a ring of muscle that forms the
colored portion of the eye around the pupil and controls the size of the pupil opening
Lens- transparent structure behind pupil that changes shape to focus images on the retina
(like camera lens)
Vision
Vision Accommodation- the process by which
the eye’s lens changes shape to help focus near or far objects on the retina
Retina- the light-sensitive inner surface of the eye, containing receptor rods and cones plus layers of neurons that begin the processing of visual information
Vision Acuity- the sharpness of vision Nearsightedness- condition in which
nearby objects are seen more clearly than distant objects because distant objects in front of retina
Farsightedness- condition in which faraway objects are seen more clearly than near objects because the image of near objects is focused behind retina
Vision
Farsighted Nearsighted Normal Vision Vision Vision
Retina’s Reaction to Light- Receptors Rods
peripheral retina detect black, white and gray twilight or low light
Cones near center of retina fine detail and color vision daylight or well-lit conditions
Color Vision Our visual system interprets differences
in the wavelength of light as color Rods are color blind, but with the cones
we can see different colors This difference occurs because we
have only one type of rod but three types of cones
Retina’s Reaction to Light
Optic nerve- nerve that carries neural impulses from the eye to the brain
Blind Spot- point at which the optic nerve leaves the eye, creating a “blind spot” because there are no receptor cells located there
Fovea- central point in the retina, around which the eye’s cones cluster
Blindspot
Vision- ReceptorsReceptors in the Human Eye
Cones Rods
Number
Location in retina
Sensitivity in dim light
Color sensitive? Yes
Low
Center
6 million
No
High
Periphery
120 million
Rods
Cones
Processing Visual Information
Ganglion cells— neurons that connect to the bipolar cells, their axons form the optic nerve
Bipolar cells— neurons that connect rods and cones to the ganglion cells
Optic chiasm— point in the brain where the optic nerves from each eye meet and partly crossover to opposite sides of the brain
Visual Pathway
Axons of the ganglion cells come together to form the optic nerve
Half of optic nerve fibers cross into opposite hemisphere and synapse onto LGN (lateral geniculate nucleus)
LGN neurons synapse onto primary visual cortex
Pathways from the Eyes to the Visual Cortex
Feature Detectors
nerve cells in the brain that respond to specific features
shape
angle
movement
Stimulus
Cell’s responses
Visual Information Processing
How The Brain Perceives
The Necker Cube
Illusory Contours
Parallel Processing
simultaneous processing of several aspects of a problem simultaneously
Visual Information
Color Mixing
Two basic types of color mixingsubtractive color mixture
example: combining different color paintsadditive color mixture
example: combining different color lights
Additive Color Mixture By combining lights
of different wavelengths we can create the perception of new colors
Examples:red + green = yellowred + blue = purplegreen + blue = cyan
Trichromatic Theory of Color Vision
Researchers found that by mixing only three primary lights (usually red, green and blue), they could create the perceptual experience of all possible colors
This led Young and Helmholtz to propose that we have three different types of photoreceptors, each most sensitive to a different range of wavelengths
Visual Information Processing Trichromatic (three color) Theory
Young and Helmholtz three different retinal color receptors
red green blue
Color Vision
Some people cannot tell the difference between certain colors. The most common form is the inability to see the colors of red or green.
People who suffer red-green blindness have trouble perceiving the number within the design
Color-Deficient Vision
Opponent Process Theory of Color Vision
Some aspects of our color perception are difficult to explain by the trichromatic theory alone
Example: afterimagesif we view colored stimuli for an
extended period of time, we will see an afterimage in a complementary color
Color Blindness
Visual Information Processing
Opponent-Process Theory- opposing retinal processes enable color vision
“ON” “OFF”
red green
green red
blue yellow
yellow blue
black white
white black
Opponent Process- After Image
Complimentary-After Image
Opponent-Process Theory To account for phenomena like
complementary afterimages, Herring proposed that we have two types of color opponent cellsred-green opponent cellsblue-yellow opponent cells
Our current view of color vision is that
it is based on both the trichromatic and opponent process theory
Color Constancy
Perceiving familiar objects as having consistent color, even if changing illumination alters the wavelengths reflected by the object
Visual Information Processing
Overview of Visual SystemOverview of Visual System
• The eye is like a camera, but instead of using film to catch the light we have rods and cones
• Cones allow us to see fine spatial detail and color, but cannot function well in dim light
• Rods enable us to see in dim light, but at the loss of color and fine spatial detail
• Our color vision is based on the presence of 3 types of cones, each maximally sensitive to a different range of wavelengths
Audition Audition
the sense of hearing Frequency
the number of complete wavelengths that pass a point in a given time
Pitch a tone’s highness or lowness depends on frequency
The Intensity of Some Common Sounds
Audition- The Ear Outer Ear
ear lob and auditory canal Middle Ear
chamber between eardrum and cochlea containing three tiny bones (hammer, anvil, stirrup) that concentrate the vibrations of the eardrum on the cochlea’s oval window
Audition- The Ear Inner Ear
innermost part of the ear, continuing the cochlea, semicircular canals, and vestibular sacs
Cochlea coiled, bony, fluid-filled tube in the inner
ear through which
Transduction of Sounds
The structures of the ear transform changes in air pressure (sound waves) into vibrations of the Basilar Membrane
As the Basilar Membrane vibrates it causes the hairs in the Hair Cells to bend
The bending of the hairs leads to a change in the electrical potential within the cell
Audition 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 a tone, thus enabling us to sense its pitch
How We Locate Sounds
Audition
Conduction Hearing Loss hearing loss caused by damage to the
mechanical system that conducts sound waves to the cochlea
Nerve Hearing Loss hearing loss caused by damage to the
cochlea’s receptor cells or to the auditory nerve
Audition Older people tend to hear low
frequencies well but suffer hearing loss for high frequencies
1time
10times
100times
1000times
32 64 128 256 512 1024 2048 4096 8192 16384
Frequency of tone in waves per second
Low Pitch High
Amplitude required forperception relative to 20-29 year-old group
Chemical and Body Senses
• Olfaction (smell)• Gustation (taste)• Touch and temperature• Pain• Kinesthetic (location of body)• Vestibular (balance)
TouchTouch Skin Skin
SensationsSensations pressurepressure
only skin only skin sensation with sensation with identifiable identifiable receptorsreceptors
warmthwarmth coldcold painpain
Pain Gate-Control Theory (Melzack & Wall)
theory that the spinal cord contains a neurological “gate” that blocks pain signals or allows them to pass on to the brain
“gate” opened by the activity of pain signals traveling up small nerve fibers
“gate” closed by activity in larger fibers or by information coming from the brain
TasteTaste Taste SensationsTaste Sensations
sweetsweet soursour saltysalty bitterbitter
Sensory InteractionSensory Interaction the principle that one sense may the principle that one sense may
influence anotherinfluence another as when the smell of food influences its as when the smell of food influences its
tastetaste
Taste
• Sweet
• Sour
• Salty
• Bitter
Smell
Receptor cells inolfactory membrane
Nasal passage
Olfactorybulb
Olfactorynerve
Age, Sex and Sense of Smell
Women
Men
10-19 20-29 30-39 40-49 50-59 60-69 70-79 80-89 90-99Age Group
4
3
2
0
Numberof correct
answers
Women and young adults have best sense of smell
Body Position and Body Position and MovementMovement
KinesthesisKinesthesis the system for sensing the position the system for sensing the position
and movement of individual body and movement of individual body partsparts
Vestibular SenseVestibular Sense the sense of body movement and the sense of body movement and
positionposition including the sense of balanceincluding the sense of balance