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What is sensation?
- Sensation:The Activation of receptors in various sense organs—eyes, ears, nose, taste buds.
- Sensory receptors:Specialized forms of neurons; the cells that make up the nervous system
- Transduction:Conversion of outside stimuli into a neural signal in the brain.
- Just noticeable difference (JND): The smallest difference between 2 stimuli that is detectable 50 percent of the time.
- Absolute threshold: Smallest amount of energy needed for a person to continuously detect a stimulus 50 percent of the time it is present.
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What are subliminal stimuli, and what affect can they have on us?
- Stimuli that are below the level of conscious awareness: Just strong enough to activate the sensory receptors, but not strong enough for people to be consciously aware of them. Research suggests that subliminal perception does not work in advertising
- Supraliminal stimuli: Stimuli that you can be consciously aware of but since your attention is directed elsewhere, you are not
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What is habituation and sensory adaptation? How are they different?
- Habituation: Tendency of the brain to stop attending to constant, unchanging information
- Sensory adaptation: The tendency of sensory receptor cells to become less responsive to a stimulus that is unchanging
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What are the properties of light?
- Brightness: Is determined by the amplitude of the wave, how high or low the wave actually is High—bright, low—dimmer.
- Color: Determined by the length of the wave
- Saturation: Purity of the color people see; mixing in black or gray would lessen the saturation.
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What are the structures of the eye?
- Retin: Final stop for light in the eye, Ganglion cells, Bipolar cells, Photorecptorst that respond to various light waves
- Photoreceptors: Rods--Adapted for vision of dim light
- Cones: Adapted for color vision, daytime vision, and detailed vision. Required a lot of light
- Fovea: Helps focus
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What are some lens deficits?
- Presbyopia: Develops as we age. Decreased flexibility of the lens and, therefore, inability to focus on nearby objects
- Cataract: The lens becomes cloudy
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What are some eye shape deficits?
- Myopia: Can focus well on nearby objects but difficulty with distant objects. Eyes are elongated.
- Hyperopia: Can focus on distant objects but not so will on close object. Eyeballs are flattened.
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What is Glaucoma?
Increased amount of pressure in the eyeball which can lead to optic nerve damage and the loss of peripheral vision
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What is the Trichromatic theory?
- Theory of color vision that proposes three tyes of cones--red, blue and green
- Afterimages: When a visual sensation persists for a brief time even after the original stimulus is removed
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What is the Opponent process-theory?
- We perceive color not in terms of independent colors but in terms of a system of paired opposites
- Red vs. green
- Yellow vs. blue
- White vs. black
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What is monochrome colorblindness?
A person’s eyes either have no cones or have damaged their cones to the point of not working
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What is red-green color blindness?
- Either the red or the green cones are not working
- Protanopia: red cones
- Deuteranopia: green cones
- Tritanonpia: lack of functioning blue cones
- Sex-linked inheritance
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What are sound waves and what are the properties of sound waves?
- Vibration of molecules in the air or another medium
- Amplitude: Volume
- Wavelength: Frequency or the pitch of the soundo
- Purity: Timbre (richness in the tone of the sound)
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How do we measure sound waves?
- Hertz(Hz): cycles of waves per second, a measurement of frequency
- Humans have a limited:20Hz- 20,000Hz
- Greatest sensitivity from about 2000-4000Hz
- Decibels: dB unit of measure for loudness
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What is the structure of the outer ear?
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What is the structure of the middle ear?
Stapes
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What is the structure of the inner ear?
- Cochlea: Snail shaped structure of the inner ear
- Basilar membrane
- Organ of Corti: Contains receptor cells for sense of hearing
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What are the different theories of pitch?
- Pitch: Corresponds to the frequency of the sounds waves
- Place theory: The stimulation of hair cells in different locations on the organ of the Corti
- Frequency theory: Related to the speed of vibrations in the basilar membrane
- The basilar membrane vibrate unevenly when the frequency is above 1000Hz—place theory
- Neurons associated with the hair cells fire as fast as the basilar membrane vibrates up o 1000Hz—frequency theory
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What are the two ways in which a person can be hearing impaired, and how can we help people who are hearing impaired?
- Conduction hearing impairment can result from: Damaged eardrum, Damaged stapes
- Nerve hearing impairment can result from: Damages in the inner ear, Damage in the auditory pathways and cortical areas of the brain
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What are taste buds? Where are they located? What are their properties and structures?
- Papillae: Taste buds line the walls of these
- Come in two different sizes: Smaller more numerous and are touch sensitive and rough. Larger ones contain the taste buds
- Stimulated by molecules of food--Chemical sense
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What are the somesthetic senses?
The body senses consisting of the skin senses, the kinesthetic sense, and the vestibular senses
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What are the cutaneous senses?
- Skin senses: Pressure, warmth, cold, pain, vibration, movement, and stretch
- Sensory receptors: Some places receptors are densely packed (fingertips and lips)
- Phantom limbs
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What is the kinesthetic sense?
Sense of the location of body parts in relation to the ground and each other
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What is the vestibular sense?
- The direction of tilt and the amount of acceleration of the head and the position of the head with respect to gravity
- Plays a key role in posture and balance
- Motion sickness
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What are some of the gestalt principles of perception?
- Figure-foreground: The tendency to perceive objects, or figures, as existing of a background
- reversible figures: visual illusions in which the figure and ground can be reversed
- similarity
- Proximity- nearness,
- closure
- continuity
- common region
- contiguity: tendency to perceive two things that happen close together in the time as being related
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What is depth perception, and how are we able to perceive it?
- The ability to perceive the world in 3D
- Linear perspective: the tendency for parallel line to converge on one another
- Relative size: when objects that a person expects to be a certain size appear to be small they are assumed to be farther away
- Interposition-: an object that appears to be blocking part of another object is in front of the second object and closer to the viewer
- Aerial perspective: a haziness that surrounds objects that are farther away from the viewer causing the distance to be perceived as greater
- Texture gradients: textured surfaces to appear to become smaller and finer as distance increases
- Motion parallax-
- Monocular cues:Cues for perceiving depth based on one eye only, Accommodation
- Binocular cues: Cues for perceiving depth based on both eyes Convergence-The rotation of the two eyes in the sockets to focus on a single object, resulting in greater convergence for closer objects and lesser convergence if objects are distant. Binocular disparity-The difference in images between the two eyes, which is greater for objects that are close and smaller for distant objects
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What is the Herman Grid illusion?
Possibly due to the response of the primary visual cortex
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• What factors can influence perception?
- Perceptual set: The tendency to perceive things a certain way because previous experiences or expectations influences those perceptions
- Top-down processing: The use of preexisting knowledge to organize individual features into a unified whole
- Bottom-up processing: The analysis of the smaller features to build up to a complete perception
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