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Unit 4- Perception and Sensation (The Eye (Iris- a ring of muscle tissue…
Unit 4- Perception and Sensation
Light Energy
Hue
- the dimension of color that is determined by the wavelength of light; what we know as blue, green, etc.
Intensity
- the amount of energy in a light or sound wave, which we perceive as brightness or loudness, as determined by the wave's amplitude.
Wavelength
- the distance from the peak of one lighter sound wave to the peak of the next. Electromagnetic wavelengths vary from the short blips of cosmic rays to the long pulses of radio transmission.
The Eye
Iris
- a ring of muscle tissue that forms the colored portion of the eye around the pupil and controls the size of the pupil opening in response to light intensity.
Lens
- the transparent structure behind the pupil that changes shape to help focus images on the retina.
Pupil
- the adjustable opening in the center of the eye through which light enters.
Retina
- the light-sensitive inner surface of the eye, containing the receptor rods and cones plus layers of neurons that begin the processing of visual information.
Cornea
- protects eye and bends light to provide focus; where light enters the eye.
accommodation
- the process by which the eye's lens changes shape to focus near or far objects on the retina.
Audition (Hearing)
Sound Waves
Place Theory
- in hearing, the theory that links the pitch we hear with the plates where the cochlea's membrane is stimulated *High pitched sounds
Frequency Theory
- in hearing, the theory that the rate of nerve impulses traveling up the auditory nerve matches frequency of a tone, thus enabling us to sense its pitch. *Low Pitched Sounds
Pitch
- a tone's experienced hinges or lowness
*depends on frequency
Frequency- number of complete wavelengths that pass a point in a given time
Low Frequencies vibrate more of membrane, including the end
High Frequencies produce large vibrations near beginning of cochlea membrane
The Ear
Outer Ear-
Visible section that channels waves through the auditory canal to the eardrum
Eardrum
- a tight membrane that vibrates after it receives the waves
Middle Ear
- chamber between the eardrum and cochlea containing three tiny bones (hammer, anvil, stirrup) that concentrate the vibrations of the eardrum on the cochlea's oval window
Cochlea
- a coiled, bony, fluid-filled tube in the inner ear; sound waves traveling through the cochlear fluid trigger nerve impulses
Inner Ear
- the innermost part of the ear, containing the cochlea, semicircular canals, and vestibular sacs
The Retina
Optic Nerve
- the nerve that carries neural impulses from eye to brain.
Blind Spot-
the point at which the optic nerve leaves the eye, creating a "blind spot" because no receptor cells are located there.
Cones
- retinal receptors that are concentrated near the center of the retina and that function in daylight or in well-lit conditions. Detect fine detail and give rise to color sensations.
Fovea
- the central focal point in the retina, around which the eye's cones cluster.
Rods
- retinal receptors that detect black, white, and grey; necessary for peripheral and twilight vision, when cones don't respond.
Visual Information Processing
Parallel Processing
- The processing of many aspects of a problem simultaneously; the brain's natural mode of information processing for many functions, including vision. Contrasts with step-by-step processing of most computers and conscious problem solving.
Young-Helmholtz Trichromatic Theory
- The theory that the retina contains three different color receptors- one most sensitive to red, one to blue, one too green. When stimulated in combinations, can produce perception of any color.
Feature Detectors
- Nerve cells in the brain that respond to specific features of the stimulus, such as shape, angle, or movement.
Opponent-Processing Theory
- opposing retinal processes enable color vision.
Sensation and Perception
Sensation
-the process that allows our brains to interpret information via stimulus energies from our environment
Perception
-the process of interpreting and recognizing sensory stimuli and enables us to recognize meaningful objects and events
Bottom-up processing
-enables our sensory system to detect the lines, angles, and color of objects
Top-down processing
-allows us to interpret what our senses detect
Transduction
-the conversion of one form of energy into anther. In sensation, it is the transforming of stimulus energies (in sights, sounds, smells) into neural impulses our brains interpret
Attention
Selective attention
is the focusing of conscious awareness on a particular stimulus
Cocktail party effect
-shows our ability to attend to only one voice among many, but when we hear our name from across the room, our attention is immediately drawn to it
Inattentional blindness
-when we fail to see visible objects when our attention is directed somewhere else
Change blindness
-when we fail to notice the changes in our environment
The Other Senses
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Touch
Mix of four senses
Body Position and Movement
Kinesthesia
- sense of position and movement
Vestibular sense
- monitors your heads position and movement (balance)
Taste
Five basic sensations: sweet, sour, bitter, salty, umami
Smell
Chemical sense: we like certain smells more because they may bring back vivid memories
Sensory Interaction
McGurk effect
- when we see a speaker say one syllable while we hear another, we may perceive a third that blends both inputs
Abilities to form Perception
Figure-Ground- the organization of the visual field into objects (figures) that stand out from their surroundings (ground).
Grouping- the perceptual tendency to organize stimuli into coherent groups.
Proximity- nearby figures grouped together.
Continuity- perceive smooth, fluid patterns.
Closure- fill in gaps to complete a whole object.
Thresholds
Absolute threshold
-the minimum stimulation needed to detect a stimulus 50 percent of the time
Difference threshold
-the minimum difference between two stimuli needed for detection 50 percent of the time (experience as
just noticeable difference
Subliminal
- below one's absolute threshold for conscious awareness
Weber's Law
- the principle that, to be perceived as different, two stimuli must differ by a constant minimum percentage
Depth Perception
Binocular Cues
- depth guess, such as retinal disparity, that depend on the use of two eyes.
Retinal Disparity
- by composing images from retinas in the two eyes, the brain computes distance- the greater the disparity between the two images, the closer the object.
Visual Cliff
- a laboratory device for testing depth perception in infants and young animals.
Monocular Cues
- Depth cues, such as interposition and linear perspective, available to either eye alone.
Depth Perception
- the ability to see objects in three dimensions although the images that strike the retina are two-dimensional; allows us to judge distance.
Perpetual Sets
Perpetual set
- A mental predisposition to perceive one thing and not another and affects what we perceive
Sad music predisposes people to perceive a sad meaning in homophonic words ex:
mourning vs. morning
ESP
Extrasensory perception (ESP)
- the controversial claim that perception can occur apart from our sensory input
Telepathy
- "mind-to-mind" communication
Clairvoyance
- perceiving remote events
Precognition
- perceiving future events
Parapsychology
- the study of paranormal phenomena