PSYC 320: EXAM 3
139 Cards in this Set
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7.1 Optic flow: flow of stimuli in the environment that occurs when an observer moves relative to the environment. Longer arrows= more rapid flow.
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Forward movement= expanding optic flow. Backward movement= contracting optic flow.
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ecological approach
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-JJ Gibson
-perception is not stationary experience
-stresses relationship between organism and environment and it's relation between perception and action
-The senses do not work in isolation. (vision + motion + audition..)
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Ecological approach to perception
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perception
-This approach focuses on studying perception as it occurs in natural settings, particularly emphasizing the role of observer movement.
-Study how people perceive as they move through the environment.
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4 lobes of brain
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- Frontal - voluntary movement, thinking, personality
-Occipital - vision
-Parietal - spatial, location, attention, motor cortex
- Temporal - hearing, language processing, memory
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optic flow and it's two characteristics
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movement of elements relative to observer
1) flow is more rapid near moving observer. Fast near observer, slower further away= Gradient of Flow
2)no flow at destination toward which the observer is moving. Absence of flow = Focus of Expansion.
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Invariant Information:
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Information that remains constant even when the observer is moving.
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physiology of navigation
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optic flow neurons - neurons in the medial superior temporal area (MST) of monkeys respond to flow patterns
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Medial Superior Temporal Area
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neurons that respond to optic flow patterns found in MST
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Self-produced information:
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When a person makes a movement, that movement created info, and this info is, in turn, used to guide further movement.
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Monkey MST experiment
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Neuron 1 in the monkey’s MST responds to anexpanding stimulus but not a stimulus with circular movement. Neuron 2 respondsto circular movement but not to expansion.
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Schindlers experiment:
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Tested 2 patients w/ parietal lobe damage who had trouble pointing to visual stimuli (optic ataxia).
2 Cylinder task fig 7.21 pg. 166
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Experiment results:
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The dorsal stream, which was damaged in the ataxia patients, not only provides guidance as we reach toward an object but also guides us away from potential obstacles. The parietal lobe provides guidance for movement, this mechanism operates unconsciously. But the patients with optic ataxi…
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Optic ataxia
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Patients suffering from this syndrome produce inaccuratereaching movements towards a target or object in space.
(damage in PARIETAL lobe)
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mirror neurons
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neurons that respond both when the monkey observes someone else grasping an object such as food on a tray and when the monkey itself grasps the food.
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Fig 7.5 on page 156
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Fig 7.6 on page 157
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Mirror Neurons
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When you see someone do something, you can do the same thing. These exist in the brains premotor cortex (frontal lobe) to fire not only when an animal performs an action but when it sees its mother perform the same action.
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what are mirror neurons for?
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facilitate learning by imitation (language, skills)
social interactions (empathy, connecting with others)
autism may be caused by deficiency in mirror neurons
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Parietal Lobe
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Responsible for touch perception (knowing object is hot or cold), fine motor movements. Divided in two portions. One of them is located behind the frontal lobe and at the top of the brain. While the right area determines ability to find ways through familiar and new places, the left sid…
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parietal lobe does what
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-provides guidance for movement
-operates unconsciously
-patients with optic ataxia lost ability
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Kinetic Depth Effect
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–movementof an object’s 2-D shadow can change into perception of a 3-D object
•Thisis an example of structure-from-motion
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Structure-from-motion
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Different parts of an object have different relative motions on the retinal image.
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Affordance:
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Information that indicates what an object is used for. How the stimulus can be used. Ex: seeing a chair as something to sit on or a flight of stairs as something to climb.
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Parietal Reach Region (PRR):
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a network of areas in the parietal cortex that contains neurons that are involved in reaching behavior.
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Real Motion:
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object is physically moving, actual motion of an object. (perceiving a car driving by, people walking, etc)
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Apparent motion: most famous & studied
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displacement of objects (when one stationary object is replaced by another). No actual, real, motion between stimuli. Presented one after another. Motion we perceive in movies, on TV, and in moving signs that are used for advertising and entertainment.
Fig 8.5 page 179
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induced movement
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occurs when motion of one object (usually a large one) causes a nearby stationary object (usually smaller) to appear to move. EX- moon usually appears stationary in sky, but if clouds are moving then moon may appear to be moving through clouds.
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motion aftereffect (MAE)
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occurs after viewing a moving stimulus for 30-60 seconds and then viewing a stationary stimulus, which appears to move. (waterfall illusion)
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waterfall illusion:
Fig 8.6 page 179
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example of a motion aftereffect. observation of motion in one direction (waterfall) can cause perception of motion in the opposite direction when viewing stationary objects in environment
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motion agnosia
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-Damage to the cortex resulting in inability to perceive movement
-Extremely debilitating and dangerous for the patient
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example of motion agnosia from text
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43 yr old woman, lost ability to perceive motion due to stroke. damaged area of cortex involved in motion perception.
-made it difficult for her to pour tea or coffee because liquid appeared frozen, didn't know when to stop pouring
-difficult to follow dialogue (couldn't see motions of …
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functions of movement perception
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1. survival in environment (predators and prey)
2. perceiving objects
3. perceptual organization
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perceiving objects
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–Movementof objects or the observer’s movement through objects help perceive the 3D organization of stimuli
–kinetic depth effect
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perceptual organization
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grouping objects that move together. (point-like walker stimulus) movement transforms dots that appear unrelated into pattern that immediately becomes meaningful.
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Damage to the MT (section of the brain) impairs ____ ______.
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motor function
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neural mechanism
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-neurons that are sensitive to direction of motion
-sequential activation in a visual field induces the perception of movement
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inhibitory neural circuit
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-inhibitory connections
-only responds from right to left, not left to right
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Top-Down Process
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Process in perception in which you apply your experience and expectations to interpret what each item must be in context
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Intelligence of Movement Perception
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-top down perception
-obj meaning influences movement perception
-knowledge about human body influences movement perception
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biological motion
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movement of person or other living organism, from point-light walkers.
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Point-Light Walker Stimulus
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created by placing small lights on people's joints and then filming the patterns created by these lights when people walk and carry out other actions in the dark.
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grossman and blake point-light experiment
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proved that there is a specialized area in brain for biological motion by measuring observers' brain activity as they viewed dots that moved similarly to point-light walker dots, but were scrambled.
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superior temporal sulcus (STS)
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part of the brain that may be involved in detecting biological motion. activity greater for biological motion than scrambled
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FFA in grossman and blake experiment
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activated more by biological motion than by scrambled motion
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EBA in grossman and blake experiment
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did not distinguish between biological and scrambled motion
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did not distinguish between biological and scrambled motion
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Temporarily disrupt the functioning of a particular area of brain by applying a pulsating magnetic field using a stimulating coil placed over the persons skull.
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cue approach to depth perception
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explains depth perception, focuses on identifying info in the retinal image that is correlated with depth in the scene.
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Oculomotor Cues are created by:
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Convergence, the inward movement of the eyes that occurs when we look at nearby objects. Accommodation, the change in the shape of the lens that occurs when we focus on objects at various distances.
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monocular depth cues
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cues that work only with one eye. include accommodation, pictorial cues (depth for 2d), movement based cues
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pictorial cues
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sources of depth information that can be depicted in a picture
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occlusion
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depth cue in which one object hides or partially hides another object from view, causing the hidden object to be perceived as being farther away.
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relative height:
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Objects w/ their bases closer to the horizon are usually seen as being more distant. This means that being higher in the field of view causes objects on the ground to appear farther away, whereas being lower in the field of view causes objects in the sky to appear farther away
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Relative size:
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when 2 objects are of equal size, the one that is farther away will take up less of your field of view than the one that is closer.
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familiar size
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depth cue based on knowledge of the typical size of objects, we judge distant based on our prior knowledge of the sizes of objects.
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perspective convergence
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when parallel lines extend out from observer, looks like they converge (railroad tracks) as distance increases
the perception that parallel lines in the distance converge as distance decreases.
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Linear Perspective
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Based on the observation of parallel lines that appear to converge as they recede from the viewer, meeting at a vanishing point on the horizon line.
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atmospheric perspective
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when distant objects appear less sharp than nearer objects and often have a slight blue tent.
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texture gradient
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elements that are equally spaced in a scene appear to be more closely packed as distance increases.
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motion parallax
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occurs when, as we move, nearby objects appear to glide rapidly past us, but more distant objects appear to move more slowly. nearby objects appear to speed by in a blur, and objects on horizon moving only slightly.
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binocular disparity
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arises when a given point in the external world does not project to the corresponding points on the left and right retinae.
Occurs when the retinal images of an object fall on disparate points on the 2 retinas.
(pic)
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Corresponding retinal points
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The points on each retina that would overlap if one retina were slid on top of the other.
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Horopter
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imaginary surface that passes through the point of fixation and indicates the location of objects that fall on corresponding points on the two retinas.
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non-corresponding retinal points
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2 points, one on each retina, that would not overlap if the retina were slid onto each other.
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Retinal disparity
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images from the two eyes differ; the slight difference in two retinal images is due to the angle from which each eyes views an object
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Disparity-selective cells (binocular depth cell):
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a neuron in the visual cortex that responds best to stimuli that fall on points separated by a specific degree of disparity on the 2 retinas.
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Stereoscope
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an instrument that produces three dimensional effect by simultaneously presenting slightly different two-dimensional views to left and right eyes. creates disparity
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Random dot stereogram (RDS)
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- Reinforces that the brain does not interpret the retinal image as a coherent image, but response to various sources of information
- We can rely just on disparity to determine depth
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visual angle
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The angle of an object relative to the observer's eye
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size constancy
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the perception that an object stays the same size despite changes in distance from which it is viewed
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Emmert's Law
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law stating that the size of an afterimage depends on the distance of the surface against which the afterimage is viewed. the farther away the surface, the larger the afterimage appears
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Visual Illusions
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Misperceptions of visual stimuli.
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Muller-Lyer Illusion
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-the most famous of all visual illusions
-lines of equal length appear unequal because of the orientation of the arrow marks at the end
-also has dumbbell version
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Ponzo Illusion
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an illusion where two horizontal lines of equal length are drawn inside two converging lines, but the line in the narrower section of the converging lines is perceived to be longer
Depth is typically involved with illusions
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Ames room illusion
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Two people of equal size appear very different in size in this room
due to size distance scaling and relative size
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2 definitions of sound:
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Physical: sound is pressure changes in the air or other medium.
Perceptual: sound is the experience we have when we hear.
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Y axis (up and down) is magnitude.
•Amplitude
–Decibel (dB)
–Number of dB = 20 x log(P/P0)
–(P: the sound pressure of the stimulus, P0: a standard pressure)
–P0:=the pressure of a 1000Hz tone at threshold.
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X axis (left to right) is frequency.
– Hertz (Hz) à one cycle per second
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Pure Tone
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-a sound consisting of a single frequency (tones produced under laboratory conditions). A tone with pressure changes that can be described by a single sine wave.
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What is the amplitude?
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The size of the pressure change, y axis. Represents the pressure difference between atmospheric pressure and the maximum pressure of the wave.
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Frequency:
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the number of cycles per second that the pressure changes repeat. It's measures in Hertz, where 1 Hertz is one cycle per second.
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frequency and wave length
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high frequency= short wave length
and low frequency = long wave length
x axis
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Hertz (Hz)
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Hz the derived SI unit of frequency; the frequency of a periodic phenomenon that has a periodic time of 1 second; 1 cycle per second
THAT PITCH IS SO HIGH IT HERTZ
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timbre
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The quality of a sound, sometimes called "tone color." The quality that distinguishes between 2 tones that sound different even though they have the same loudness, pitch, and duration. Differences in timbre are illustrated by the sounds made by different musical instruments.
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Loudness
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the perception of intensity, soft to loud. For a tone of a particular frequency, loudness usually increases with increasing decibels.
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decibel (dB)
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unit used for loudness/sound intensity.
Unit that indicates the pressure of a sound stimulus relative to a reference pressure
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dB:Decibel
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•dB? With p=200, p0(standard pressure level)=20
dB=20 x log (200/20)= 20 x log (10)
= 20 x 1= 20
•with p = 2000
dB = 20 x log (2000/20)= 20 x log (100)
= 20x 2 = 40
With p = 20000
dB = 20 x log (20000/20)= 20 x log (1000)
= 20x 3 = 60
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Additive Synthesis: create a complex sound by combining simple sound waves.
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Fourier Analysis: reduce a complex sound wave into a collection of simple sound waves.
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Frequency Spectrum:
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Plot that indicates the amplitudes of the various harmonics that make up a complex tone. Each harmonic is indicated by a line that is positioned along the frequency axis, with the height of the line indicating the amplitude of the harmonic.
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Sound level
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In referring to the decibels or sound pressure of a sound stimulus. number of dB= 20xlog(p/p0)
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Pitch
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The quality of a sound, ranging from low to high, that is most closely associated with the frequency of a tone.
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What is the frequency hearing range?
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20 hz to 20,000 hz
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Outer ear: consists of pinna and auditory canal. Protects delicate structures of middle ear and eardrum.
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It also enhances the intensities of some sounds by means of the physical resonance.
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Eardrum (tympanic membrane):
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thin sensitive part of the ear that vibrates with the waves and as it vibrates you can hear sound
Membrane located at the end of the auditory canal that vibrates in response to pressure changes. This vibration is transmitted to the bones of the middle ear.
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Main structure of the inner ear is the liquid filled cochlea, snail like structure.
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Liquid inside cochlea is set into vibration by the movement of the stapes against the oval window.
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Cochlea
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Most important in cochlea are the basilar membrane, tectorial membrane. and hair cells.
The hairs near the BASE are stiffer, harder to vibrate, the hairs near the APEX vibrate at a lower frequency
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Cochlea
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-auditory portion of inner ear, snail shaped.
-filled with liquid, moves in response to vibrations from middle ear
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basilar membrane
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A membrane that stretches the length of the cochlea and controls the vibration of the cochlear partition.
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Hair cell
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Neuron in the cochlea that contains small hairs, or cilia, that are displaced by vibration of the basilar membrane
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They are the receptors for hearing.
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Tectorial membrane:
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A membrane that stretches the length of the cochlea and is located directly over the hair cells. Vibrations of the cochlear partition cause the tectorial membrane to bend the hair cells by rubbing against them.
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Phase Locking:
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Firing of auditory neurons in synchrony with the phase of an auditory stimulus.
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octave
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eight steps apart-- the upper pitch vibrates exactly twice as fast as the lower. Tones that have frequencies that are binary multiples of each other. (an 800 tone is one octave above a 400-Hz tone.
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frequency spectrum
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a plot that indicates the amplitudes of the various harmonics that make up a complex tone
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Bekesy's place theory
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the frequency of a sound is indicated by the place along the cochlea at which nerve firing is highest. Each place on the basilar membrane is tuned to respond best to a different frequency. The base is tuned to high frequencies, the apex is tuned to low frequencies, and the best frequency …
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Shows what the membrane looks like when the vibration is "frozen" w/ the wave abut 2/3 of the way down the membrane. Wave spreads. The wave reached the peak at a particular location.
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side views of traveling wave caused by a pure tone, position of membrane at 3 instances in time as wave moves from base to apex of cochlear partition. Height of wave reaches peak at P then gradually subsides.
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Tonotopic Map
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Placing electrodes at diff places along the length of the cochlea and measuring the electrical response to diff frequencies.
An orderly map of frequencies along the length of the cochlea.
- Apex responds best to low frequencies
- Base responds best to high frequencies
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the primary auditory receiving area
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located in temporal lobe, receives signals via nerve fibers from the medical geniculate nucleus in the thalamus. Primary receiving area for hearing.
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Auditory localization:
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perception of the location of a sound source. Locating of sound sources in auditory space.
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Location cues:
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in hearing, characteristics of the sound reaching the listener that provide info regarding the location of a sound source.
2 kinds of location cues: binaural and monaural.
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Binaural cues:
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using info reaching both ears to determine the azimuth (left-right position) of sounds.
2 binaural cues: interaural time difference and interaural level difference.
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interaural time differences (ITD):
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difference in the time between when a sound reaches the left ear and when it reaches the right ear.
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interaural level differences
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•Capture the difference in thelevel of the sound intensity (sound pressurelevel) that a sound reaches the left and right ears
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3 directions used for studying sound localization, fig 12.3 page 291:
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Azimuth (left-right)
Elevation (up-down)
Distance
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Monaural Cues:
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cue that depends on info from only one ear.
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Spectral Cue:
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primary monaural cue for localization, the dist. of frequencies reaching the ear that are associated with specific locations of a sound. The differences in frequencies are caused by interaction of sound with the listeners head and pinnae.
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Primary auditory cortex: A1
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an area of the temporal lobe that receives signals via nerve fibers from the medical geniculate nucleus in the thalamus.
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Jeffress Model:
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the neural mechanism of auditory localization the proposes that neurons are wired to each receive signals from the 2 ears, so that different neurons fire to different interaural time differences.
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Speech sounds are produced by the position/movement of structures within the vocal apparatus...
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structures within the vocal apparatus...
which produce patterns of pressure changes in the air called the acoustic stimulus/acoustic signal.
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Acoustic signal/stimulus.
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The pattern of frequencies and intensities of the sound stimulus. The acoustic signal for most speech sounds is created by air that is pushed up from the lungs past the vocal cords and into the vocal tract.
The sound that's produced depends on the shape of the vocal tract as air is pushe…
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Articulators
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lower jaw, lips, teeth, gums, tongue, hard palate and soft palate/velum
The shape os the vocal tract is altered by moving the articulators.
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Formants:
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horizontal band of energy in the speech spectrogram associated with vowels.
Each vowel sound has a characteristic pattern of formants that's determined by the shape of the vocal tract for that vowel.
Fig 13.2 pg 319: the peaks in the pressure changes are the formants
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Each vowel sounds has a characteristic series of formants.
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The first formant has the lowest frequency; the second formant is the next highest, so on.
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Sound spectrogram:
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a plot showing the pattern of intensities and frequencies of a speech stimulus.
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phoneme
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-the smallest unit of sound, shortest segment of speech, that if changed, would change the meaning of a word. (hip-tip, cat-hat, dog-dig)
-–consonants and vowels
-•English has about 40 different phonemes
•Different languages have different phonemes
–E.g., Japanese does not distinguish…
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Speech segmentation:
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the process of perceiving individual words from the continuous flow of the speech signal. Perception of individual words in a conversation. Knowledge of words meanings & prior knowledge are responsible for organizing sounds and separating words.
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the segmentation problem
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there are no clear cut distinctions in a spoken utterance
it is up to a listener to decide which phonemes go together and which do not
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Transitional probabilities:
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the chances that one sounds will follow another sound.
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Variability Problem
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- people of different sexes/sizes/ages have different pitches
- people from different countries or regions have different accents
Indexical characteristics: carry info about speakers such as their age, gender, place of origin, emotional state, and sarcastic/serious.
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Categorical perception:
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occurs when stimuli that exist along a continuum are perceived as divided into discrete categories. (example of the visible color spectrum).
Perceiving one sound at short voice onset times and another sound at longer voice onset times. The listener perceives only 2 categories across th…
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Voice Onset Time (VOT):
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the time delay between when a sound begins and when the vocal cords begin vibrating.
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Multimodal:
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our perception of speech can be influenced by info from a number of different senses.
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what is the McGurk effect?
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It illustrates that although auditory info is the major source of info for speech perception, visual info can also exert a strong influence on what we hear.
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Audiovisual Speech Perception:
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influence of vision of speech perception.
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Aphasias:
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damage to specific areas of the brain causes language problems.
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Patients with damage to Broca's Area in the frontal lobe have a condition called Broca's aphasia:
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Labored and stilted speech and can only speak in short sentences. But they can comprehend what others say.
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Broca's area
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motor speech
acute as we prepare to speak
usually in your left hemisphere
voluntary action
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Patients with damage to Wernicke's area in the temporal lobe have Wernicke's aphasia:
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They can speak fluently, but what they say is extremely disorganized and not meaningful. They have great difficulty understanding what people are saying.
Extreme cases can get, Word Deafness: cannot recognize words.
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Wernicke's Area
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Involved with:
language comprehension
*in left temporal lobe
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•Broca’s aphasia - individuals have damage in Broca’s area (in frontal lobe)
–Labored and stilted speech and short sentences but they understand others
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•Wernicke’s aphasia - individuals have damage in Wernicke’s area (in temporal lobe)
–Speak fluently but the content is disorganized and not meaningful
–They also have difficulty understanding others
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Dual Stream Model of Speech Perception:
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proposed a ventral (what) pathway starting in the temporal lobe that's responsible for recognizing speech, and a dorsal (where) pathway starting in the parietal lobe that's responsible;e for linking the acoustic signal to the movements used to produce speech.
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Motor theory of Speech perception:
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we not only perceive speech but we produce it, 2 parts of this theory.
When we hear a particular speech sound, this activates the motor mechanisms that are responsible for producing that sound, and it is the activation of these motor mechanisms that enable us to perceive the sound.
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1.) hearing a particular speech sounds activates motor mechanisms controlling the movement of the articulators, such as tongue & lips, that are responsible for producing sounds.
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2.) activation of these motor mechanisms, in turn, activates additional mechanisms that enable us to perceive the sound.
Thus, activity of motor mechanisms is the first step toward perceiving speech.
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PSYC 320 Exam 1