Download presentation
Presentation is loading. Please wait.
Published byBertram Potter Modified over 9 years ago
1
Sensation and Perception
2
Sensation – the process of detecting physical energy and transforming it into neural signals – This transformation process is called transduction Perception – selecting, organizing, and interpreting sensations Do we see the world as it actually is? – Nope. The world we see is a construct of our minds. There is no color. There is no sound.
3
Bottom up processing – Sensation to perception. Body to brain.
4
What is the smallest amount of something you can sense? Absolute threshold – the minimum amount of stimulation you can detect 50% of the time Try it.. Some common absolute thresholds include:
11
Why “50% of the time?” Signal Detection Theory – our ability to sense things is influenced by our: – Experience – some people are trained to detect specific things (police officers) – Expectations – you may/may not be ready (clowns) – Motivation – you may/may not care – Level of fatigue/alertness – you might be tired
12
Subliminal messages Can we be influenced by things below our absolute threshold? Can we be manipulated through subliminal messages? Yes and no They may have a brief effect – Priming Studies have shown that subliminal messages do not produce a lasting outcome
13
A_ _OM_BI_E
16
How much does a stimulus have to change before we notice a difference? For example, how bright does a light need to be before we can tell it is brighter? How much does a sound need to change before we can tell it is louder? Difference Threshold/Just Noticeable Difference (JND)- minimum difference between two stimuli required for detection 50% of the time
17
A quick experiment..
18
Weber’s Law – to be perceived as different, two stimuli must differ by a constant minimum percentage In other words, it’s not the amount of stimuli that matters, it’s the percentage; it’s the ratio of the second stimulus to the first Light intensity – 8% Weight – 2% Tone frequency -.3%
19
Other examples Suit and sweater, which first? New cars
20
Sensory Adaptation Diminished sensitivity as a result of constant stimulation Do you notice the chair pressing against your legs? If you put a band aide on, very soon you won’t notice it So then if you stare at something, shouldn’t it disappear as the sense receptors in your eye become used to it?
21
Yes It should.. It would.. But… Your eyes are always moving, even when you stare Try this…
22
Phototransduction Conversion of light energy into neural signals the brain can understand
23
Light and color Light can behave as a wave or a particle Wavelength – the distance from the peak of one wave to the peak of the next
24
Hue (color) – dimension determined by the wavelength of light
25
Wavelength (Hue) Different wavelengths of light result in different colors. 400 nm 700 nm Long wavelengths Short wavelengths Violet IndigoBlue Green Yellow OrangeRed
26
Intensity – amount of energy in a wave, determined by amplitude (i.e. how “bright” a light is)
27
Intensity (Brightness) Blue color with varying levels of intensity. As intensity increases or decreases, blue color looks more “washed out” or “darkened.”
28
The spectrum of electromagnetic energy
29
Parts of the Eye Cornea – outer covering Pupil – adjustable opening in center of eye Iris – muscle that controls the pupil Lens- transparent structure behind the iris that changes shape to focus images Retina – inner surface of the eye. Contains receptor rods and cones, and a bunch of other neurons (bi-polor, ganglion cells)
32
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
34
Rods Cones
36
Nearsightedness – nearby objects are seen more clearly Farsightedness – faraway objects are seen more clearly
37
Optic nerve- carries neural impulses from the eye to the brain Fovea- central point in the retina, where the eye’s cones cluster Blind spot See if you can find your blind spot..
39
Processing visual information
40
Feature Detection
41
Parallel processing – processing several aspects of a problem simultaneously Blindsight – seeing without seeing. Huh?
42
Color Vision Trichromatic theory (Young-Helmholtz) – since any color can be created by combinations of red, blue, and green, the eye must have three types of receptors for these three colors Subtractive- subtracts wavelengths from the reflected light Additive
43
Color blindness
45
8% of males show a color weakness, but only.05% of females Who’s better at discriminating color? Why?
46
Opponent-Processing theory Yellow is a mixture of red and green light, but people blind to red and green can often see yellow. How is this possible? Afterimages
47
After Images Stare at the eye of the red parrot while you slowly count to 20, then immediately look at one spot in the empty birdcage. The faint, ghostly image of a blue-green bird should appear in the cage.
48
Opponent Colors Gaze at the middle of the flag for about 30 Seconds. When it disappears, stare at the dot and report whether or not you see Britain's flag.
50
Complementary Afterimages
51
In the nervous system, color processing cells are grouped together like this: Red-green Blue-yellow Black-white When you stare at one color, you exhaust that receptor, so when you look at a white page, you see the opponent color
52
Opponent Process Theory Hering proposed that we process four primary colors combined in pairs of red-green, blue- yellow, and black-white. Cones Retinal Ganglion Cells
53
Color Constancy Color is relative The color you see depends on the context
54
Hearing (audition)
55
What causes sound? Molecules bump into each other at different rates, causing small changes in air pressure. Your brain converts these changes to neural impulses that interprets as sound Sound energy is measured in decibels Absolute threshold for hearing is 0 decibels, a loud thunder crack is 120 120dB
57
Parts of the ear Sound travels through your outer ear and causes your eardrum to vibrate these vibrations are then transferred to the middle ear where they cause three bones – called the hammer, the anvil, and the stirrup – to vibrate The vibrations cause the fluid in the cochlea to ripple These ripples bend tiny hair cells The hair cells send neural messages to the brain = hearing
59
Loudness is determined by the number of activated hair cells Pitch Place theory Frequency theory
60
How does the brain locate sounds?
61
Hearing loss Conduction hearing loss Nerve hearing loss Cochlear implants Sensory compensation
62
Sensory interaction
63
Touch Mixture of pressure, warmth, cold, and pain Only pressure has specific nerve receptors Touch localization
64
Pain A product of the body and the brain Gate control theory Sensitivity to pain People who feel no pain Pain control
65
Taste Chemical sense Taste buds o Regeneration Super tasters
66
Taste Traditionally, taste sensations consisted of sweet, salty, sour, and bitter tastes. Recently, receptors for a fifth taste have been discovered called “Umami”. Sweet Sour Salty BitterUmami (Fresh Chicken)
67
Taste Your sensitivity to taste will decline if you: o Smoke heavily o Consume large amounts of alcohol o Grow older
68
Taste Culture and taste preferences:
69
Smell Peaks in early adulthood and then declines (like the other senses) Chemical sense (receptor cells in nasal cavity) Not filtered by thalamus Smell and memories Who has the best sense of smell? Subliminal smells T-Shirt experiments
70
Women Men 10-19 20-29 30-39 40-49 50-59 60-69 70-79 80-89 90-99 Age Group 4 3 2 0 Number of correct answers Women and young adults have best sense of smell
71
Body Position Kinesthesis Vestibular sense
Similar presentations
© 2024 SlidePlayer.com Inc.
All rights reserved.