Post on 23-Dec-2015
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Sensation and PerceptionChapter 3
Sensation
• Sensation - the activation of receptors in the various sense organs.
• Sensory receptors - specialized forms of neurons.
• Sense organs:• eyes• ears• nose• skin• taste buds
LO 3.1 Sensation and the central nervous system
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Eye Sensory Receptors
Ear Sensory Receptors
Nose Sensory Receptors
Skin Sensory Receptors
Sensation and Perception
Stimulus energy•Heat•Light
Sensory receptor •Eyes•Nose•Skin
Neural impulse
Brain•Visual •Olfactory
Sensation Perception
Sensory Thresholds• Absolute threshold - smallest amount of energy needed
for a person to consciously detect a stimulus (50% of time)
• Just noticeable difference smallest difference between two stimuli that is detectable (50% of time)
• http://www.google.com/search?hl=en&source=hp&q=van+morrison+into+the+mystic+&aq=f&aqi=g10&aql=&oq=&gs_rfai=COBXm3nlkTOXrIouEhQSl6PCFBgAAAKoEBU_Q0NSM
LO 3.1 Sensation and the central nervous system
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Habituation and Sensory Adaptation
• Habituation - tendency of the brain to stop attending to constant, unchanging information.
• Sensory adaptation - tendency of sensory receptor cells to become less responsive to a stimulus that is unchanging.
LO 3.1 Sensation and the central nervous system
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Light Amplitude
Wavelength
Psychological Aspects to Light• Brightness - amplitude
of the wave; higher waves brighter; lower waves dimmer.
• Color - length of the wave; long wavelengths red; short waves blue
• Saturation - purity of the color people see
LO 3.2 What is light
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Brightness
ColorSaturation
Structure of the EyeLO 3.3 How eyes see and see color
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• Cornea – clear membrane that covers surface of eye; protects eye and focuses most of light coming into eye.
• Pupil – hole through which light from the visual image enters eye. Pupil
Cornea
Structure of the EyeLO 3.3 How eyes see and see color
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• Iris - round muscle; can change the size of the pupil, letting more or less light into the eye; helps focus the image.
• Lens – suspended by muscles; finishes the focusing process begun by the cornea.
Lens
Iris
Retina, Rods, and ConesLO 3.3 How eyes see and see color
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• Photoreceptors that respond to various light waves
• Rods – receptors responsible for non-color vision and sensitivity to dim light.
• Cones – receptors responsible for color vision and sharpness of vision.
Optic nerve
Retina
Rod
Cone
Visual Field of left eye Visual field of right eye
Optic nerve Optic chasm
Primary visual area
Color Vision
• Trichromatic theory - theory of color vision that proposes three types of cones: red, blue, and green.
• Opponent-process theory - theory of color vision that proposes four primary colors with cones arranged in pairs: red and green, blue and yellow
LO 3.3 How eyes see and see color
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Or
Or
Color Blindness
• Monochrome colorblindess - either have no cones or have cones that are not working at all.
• Red-green colorblindess - either the red or the green cones are not working.
LO 3.3 How eyes see and see color
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Sound• Amplitude –volume
(how soft or loud a sound is).
• Wavelength –frequency or pitch
• Purity –timbre (a richness in the tone of the sound).
• http://www.youtube.com/watch?v=2RkaD9nAv34
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LO 3.4 What is sound
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Amplitude
Wavelength
Quieter Louder
Deeper pitch Higher pitch
Structure of the Ear
• Auditory canal - short tunnel that runs from the pinna to the eardrum
• Eardrum - thin section of skin that tightly covers the opening into the middle part of the ear
LO 3.4 What is sound
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Auditory canal
Eardrum
Structure of the Ear
Hammer
Anvil
Stirrup
• When sound waves hit the eardrum, it vibrates and causes three tiny bones in the middle ear to vibrate.
• Hammer• Anvil• Stirrup
Hammer
Structure of the Ear• Cochlea - snail-shaped structure of the inner ear that
is filled with fluid.
• Organ of Corti – rests in the basilar membrane; contains receptor cells for sense of hearing.
LO 3.4 What is sound
MenuOrgan of Corti
Structure of the Ear
Auditory nerve
http://www.youtube.com/watch?v=7a2aoZeZhZ8&feature=relatedhttp://www.youtube.com/watch?v=8wgfowbbTz0&feature=related
Auditory nerve - bundle of axons from the hair cells in the inner ear; receives neural message from the organ of Corti.
Theories of Pitch• Pitch - frequency of the sound waves; higher
frequencies are perceived as higher pitches.
• Place theory - states that different pitches are experienced by the stimulation of hair cells in different locations on the organ of Corti.
LO 3.4 What is sound
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Theories of Pitch
• Frequency theory - states that pitch is related to the speed of vibrations in the basilar membrane.
LO 3.4 What is sound
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Taste• Taste buds – taste receptor cells in mouth;
responsible for sense of taste
• Gustation - the sensation of a taste.
• Five Basic Tastes:• Sweet• Sour• Salty• Bitter• “Brothy”
LO 3.6 Senses of taste and smell
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LO 3.6 Senses of taste and smell
Taste
Nerve fiber
Receptor cell
Taste poreSour
Sweet
Salty
Bitter
Smell• Olfaction (olfactory
sense) – sense of smell.
• Olfactory bulbs - areas of the brain that receive information from the olfactory receptor cells.
LO 3.6 Senses of taste and smell
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Receptor
Olfactory bulb
Somesthetic Senses• Somesthetic senses - the skin
senses, the kinesthetic sense, and the vestibular senses.
1. Skin senses - the sensations of touch, pressure, temperature, and pain.
1. Kinesthetic sense - sense of the location of body parts in relation to the ground and each other.
LO 3.7 Touch, pain, motion and balance
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Somesthetic Senses
3. Vestibular senses - the sensations of movement, balance• Sensory conflict
theory in which the information from the eyes conflicts with the information from the vestibular senses resulting in dizziness.
LO 3.7 Touch, pain, motion and balance
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Perception and Constancies
• Perception - the method by which the sensations experienced at any given moment are interpreted and organized in some meaningful fashion.
• http://www.youtube.com/watch?v=L3AgO6H0H98
LO 3.8 Perception and perceptual constancies
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Constancy
• Size constancy - the tendency to interpret an object as always being the same actual size, regardless of its distance.
Constancy
• Shape constancy - the tendency to interpret the shape of an object as being constant, even when its shape changes on the retina.
Constancy
• Brightness constancy – the tendency to perceive the apparent brightness of an object as the same even when the light conditions change.
Gestalt Principles• Figure–ground - the tendency to perceive
objects as existing on a background.
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LO 3.9 Gestalt principles of perception
Gestalt Principals
• Reversible figures - visual illusions in which the figure and ground can be reversed.
Gestalt Principals
Gestalt PrinciplesLO 3.9 Gestalt principles of perception
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Similarity Proximity Continuity Closure
Development of Perception• Depth perception - the ability to perceive the world in
three dimensions
LO 3.10 Perceiving the world in three dimensions
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Monocular Cues• Monocular cues (pictorial depth cues) – cues for
perceiving depth based on one eye only.
LO 3.10 Perceiving the world in three dimensions
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LO 3.10 Perceiving the world in three dimensions
Monocular cues
Linear Perspective
Areal perspective Texture gradient Relative size
Binocular Cues• Binocular cues - cues for
perceiving depth based on both eyes.
1.Convergence - the rotation of the two eyes to focus on a single object, resulting in greater convergence for closer objects and lesser convergence if objects are distant.
Far
Near
Focal point
Left Right
Binocular Cues
• Binocular disparity - the difference in images between the two eyes, which is greater for objects that are close and smaller for distant objects.
LO 3.11 Visual illusions
Perceptual Illusions
Müller-Lyer illusion
LO 3.11 Visual illusions
Perceptual Illusions
Moon Illusion
Perceptual Illusions• Illusions of Motion:
• Stroboscopic motion - seen in motion pictures, in which a rapid series of still pictures will appear to be in motion.
LO 3.11 Visual illusions and other factors influencing perception
Factors that Influence Perception• Perceptual expectancy- the tendency to perceive
things a certain way because previous experiences or expectations influence those perceptions.
LO 3.11 Visual illusions and other factors influencing perception