Sensation and Perception Chapter 3

LO 3.1 Sensation and the central nervous system Sensation - the activation of receptors in the various sense organs. Sensory receptors - specialized forms of neurons. Sense organs: eyes ears nose skin taste buds Sensation occurs when special receptors in the sense organs are activated, allowing various forms of outside stimuli to become neural signals in the brain. Instead of receiving neurotransmitters from other cells, these receptor cells are stimulated by different kinds of energy. Menu

Eye Sensory Receptors Sensory receptor

Ear Sensory Receptors Sensory receptors

Nose Sensory Receptors

Skin Sensory Receptors Pain Light touch Cold Heat Hair movement Strong pressure

Sensation and Perception Stimulus energy Heat Light Sensory receptor Eyes Nose Skin Neural impulse Brain Visual Olfactory Sensation Perception

LO 3.1 Sensation and the central nervous system 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 When are sensations perceived Menu

Habituation and Sensory Adaptation LO 3.1 Sensation and the central nervous system 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. Turn off song Sensory receptor cells for hearing are still responding to to the sounds, but the lower centers of the brain are not sending the signals from those receptors to the cortex. Sensory receptor cells (taste, touch, smell, vision) become less responsive to a stimulus that is unchanging. Menu

Light Amplitude Wavelength

Psychological Aspects to Light LO 3.2 What is light 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 Saturation Color Brightness Menu

LO 3.3 How eyes see and see color Structure of the Eye 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. Cornea Pupil Menu

LO 3.3 How eyes see and see color Structure of the Eye 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 Menu

LO 3.3 How eyes see and see color Retina, Rods, and Cones 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. Retina Cone Optic nerve Rod Menu

Visual Field of left eye Visual field of right eye Optic nerve Optic chasm Primary visual area

LO 3.3 How eyes see and see color 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 Three primary colors. Shades of color correspond to different amounts of light received by each of the three types of cones Four primary colors. The cones are arranged in pairs Red with green and blue with yellow. Or Or Menu

If a person tires out one of the members of the pairs it weakens that members ability to inhibit the other cell. If person looks away from a red image there will be green after image as the other member of the pair fires away.

LO 3.3 How eyes see and see color 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. Menu

Sound Amplitude Amplitude –volume (how soft or loud a sound is). LO 3.4 What is sound Sound Amplitude 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. Wavelength Quieter Louder Sound waves= vibrations of the molecules of air. Frequencies= herts 20 -20,000- humans; 50-60,000- dogs; Dolphins 200,000 Deeper pitch Higher pitch Menu

LO 3.4 What is sound 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 Eardrum Auditory canal Menu

Structure of the Ear When sound waves hit the eardrum, it vibrates and causes three tiny bones in the middle ear to vibrate. Hammer Anvil Stirrup Hammer Hammer Bones amplifies the vibrations from the ear drums Stirrup, the last of these bones causes a membrane (oval window) covering the opening of the inner ear to vibrate. Stirrup Anvil

LO 3.4 What is sound 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. Organ of Corti Menu

Structure of the Ear Auditory nerve http://www.youtube.com/watch?v=7a2aoZeZhZ8&feature=related http://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. Auditory nerve

LO 3.4 What is sound 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. Menu

LO 3.4 What is sound Theories of Pitch Frequency theory - states that pitch is related to the speed of vibrations in the basilar membrane. Menu

LO 3.6 Senses of taste and smell 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” Menu

Taste Bitter Taste pore Sour Receptor Salty cell Sweet Nerve fiber LO 3.6 Senses of taste and smell Taste Bitter Taste pore Sour Sensetivity to taste depends on how many taste buds one has. Each taste bud has about 20 receptors. Receive molecules of different substances fit into a receptor like neurotransmitters. Chemical sense. Receptor cell Salty Sweet Nerve fiber Menu

Smell Olfaction (olfactory sense) – sense of smell. LO 3.6 Senses of taste and smell Smell Olfaction (olfactory sense) – sense of smell. Olfactory bulbs - areas of the brain that receive information from the olfactory receptor cells. Receptor Olfactory bulb Menu

LO 3.7 Touch, pain, motion and balance Somesthetic Senses Somesthetic senses - the skin senses, the kinesthetic sense, and the vestibular senses. Skin senses - the sensations of touch, pressure, temperature, and pain. Kinesthetic sense - sense of the location of body parts in relation to the ground and each other. Menu

LO 3.7 Touch, pain, motion and balance 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. Menu

Perception and Constancies LO 3.8 Perception and perceptual constancies 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 Menu

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.

LO 3.9 Gestalt principles of perception Figure–ground - the tendency to perceive objects as existing on a background. Menu

Gestalt Principals Reversible figures - visual illusions in which the figure and ground can be reversed.

Gestalt Principals

Gestalt Principles Similarity Proximity Continuity Closure LO 3.9 Gestalt principles of perception Gestalt Principles Similarity Proximity Continuity Closure Menu

Development of Perception LO 3.10 Perceiving the world in three dimensions Development of Perception Depth perception - the ability to perceive the world in three dimensions Menu

LO 3.10 Perceiving the world in three dimensions Monocular Cues Monocular cues (pictorial depth cues) – cues for perceiving depth based on one eye only. Menu

Monocular cues Linear Perspective Texture gradient Relative size LO 3.10 Perceiving the world in three dimensions Monocular cues Linear Perspective Texture gradient Relative size Areal perspective

Binocular Cues Binocular cues - cues for perceiving depth based on both eyes. 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. Focal point Left Right Far Near

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: LO 3.11 Visual illusions and other factors influencing perception 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.

Factors that Influence Perception 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.