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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.
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
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
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.
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
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
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.
What is Glaucoma?
Increased amount of pressure in the eyeball which can lead to optic nerve damage and the loss of peripheral vision
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
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
What is monochrome colorblindness?
A person’s eyes either have no cones or have damaged their cones to the point of not working
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
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)
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
What is the structure of the outer ear?
What is the structure of the middle ear?
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
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
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
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
What are the somesthetic senses?
The body senses consisting of the skin senses, the kinesthetic sense, and the vestibular senses
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
What is the kinesthetic sense?
Sense of the location of body parts in relation to the ground and each other
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
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
- Proximity- nearness,
- common region
- contiguity: tendency to perceive two things that happen close together in the time as being related
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
What is the Herman Grid illusion?
Possibly due to the response of the primary visual cortex
• 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