Exam 3 Deck Flashcards
Our last exam before the final !
What does RSVP stand for?
Rapid Serial Visual Presentation (RSVP)
What is Modified RSVP?
When you have two targets instead of one in a steady stream of items
What is the attentional blink?
it is the tendency not to perceive or respond to the second target stimuli that has been presented 200-500 miliseconds after the first target stimuli
Explain the ‘Fishing’ Metaphor of the Attentional Blink
The things you perceive are like things flowing by in a (dirty) river
Fishing metaphor: What happens when we Catch a Fish?
After we catch the fish our ‘net is out of the water’, and we’ll miss any other fish (targets) that come along, can explain attentional blink
Perceiving and Understanding ‘Scenes’
we perceive objects at locations within the
environmental context as part of some larger whole
– Collections of objects in the proper spatial relations to each other create “scenes”
Do we have a good picture memory?
YES! We’re very good at remembering complex scenes
– In original version, people correctly recognized 98% of 612 pictures as ‘old’
– Still 90% correct a week later
– Can be in the 80 - 90% range with sets as large as 10,000
images
What is change blindness?
The failure to notice differences between two images of a scene
A Problem: Saccade Speed
• We only make about 3–4 saccades per second
– This is too slow to account for our scene recognition abilities • We can observe more items in a scene than 3 - 4 per
second
What are Covert Attention Shifts?
we can move our attention independent of eye movements
– Attention shift without eye movement = covert attention shift
Describe the Scene Mosaic theory
• Perhaps attention shifts around a scene faster than eye movements building a collage of objects at locations that make up the scene
What are some problems with the Mosaic Idea?
• Requires a larger working memory load than we have
– Larger than the 7±2 working memory capacity
• Experimental results indicate that we can identify a scene in less than an eighth of a second (125 ms)
– Too fast for putting together a bunch of collage pieces
Define: Schema
A rough outline of a scene or situation with placeholders for details
– e.g. farm, classroom, mall
– Perhaps identified by a rough spatial frequency analysis
Are we good at recognizing a scene after we see it?
Yes, We’re really good at recognizing scenes but we’re really bad at noticing details in a scene. We have ‘placeholders’ for things that ought to be in a scene but don’t fill in those blanks unless needed
Physiology of Object Perception
• Some kinds of objects appear to be represented in specific parts of the brain
– e.g. faces appear to be represented in a special part of inferior temporal cortex
• If we’re attending to that kind of object, then that part of the brain should be more active
Define: Change Blindness
The failure to notice differences between two images of a scene
How do we extract meaning from scenes?
To extract a scene quickly from perceptual elements, we appear attend to the ‘gist’ of the scene and ignore detail
• The ‘gist’ of a scene is its core meaning, what the overall scene is
• Change perception depends on the meaning of the change – If scene meaning stays the same, we don’t notice the
change
• A market is a market, independent of the color of some
guy’s pants
The primary visual cortex is _______ and ______
retinotopic (locations close is space are close on the brain) and contralateral (right visual field processed in left hemisphere, LVG in right hemisphere)
What is the physiology of object perception?
Some kinds of objects appear to be represented in specific parts of the brain
– e.g. faces appear to be represented in a special part of inferior temporal cortex
• If we’re attending to that kind of object, then that part of the brain should be more active
How do we test the theory of object perception?
-Show pictures of faces, places, and control stimuli
• Sometimes ask subject to respond to faces
• Sometimes as to respond to places
• Measure brain activity
• Different parts of the brain light up to faces and places
How do we know it’s Attention not Perception?
• The fusiform face area likes faces
– It lights up to a face whether we’re attending to it or not – Could just be face perception
• Solution
– Show combined face/place stimulus
– Have participant attend to face or place but not both
• Same results
What could the individual neurons be doing to create these attention responses?
– Response enhancement
– Sharper tuning
– Altered tuning
all of which have been seen and studied
What does the inability to attend to contralesional space result from?
posterior parietal lobe damage (usually right
side)
Describe the waterfall illusion:
– Stare at a waterfall for a while, then stare at the still rocks beside it
• Rocks will appear to ‘crawl’ upward • After-image of downward motion is up
Why isn’t static perception enough?
• Camouflage
– Adaptations to obscure object recognition
• Sometimes motion is the best object cue
Describe the Motion Detector Model:
• Two receptors with adjacent receptive fields
• Stimulus (bug, spot of light) enters receptive field of A, then a
little later B
– First A fires, then B
• Motion detector M gets input from A & B – When A & B both fire, then M fires
What is the problem with the motion detector model?
It can’t distinguish between a small bug moving between receptive fields and a large bug in both receptive fields at once
– Both will activate A & B, thus activating M
What is a solution for the motion detector model?
• Add a ‘delay’ neuron
– Bug goes through receptive field A – A activates ‘delay’ neuron D
• Rapid adapting
• “Holds” the activation
– Later, B gets activated
– Simultaneous activation of D & B activates motion detector
describe the motion detection circut
a string of ‘delay’ neurons that can rapidly adapt, are sensitive to direction, one-way, and can also be velocity sensitive
The motion detection circuit exists in the brain through interneurons
TRUE
What are some ambiguity issues with motion perception?
• ✔ Can’t always tell direction of movement
– Due to aperture & correspondence problems
• Can perceive movement when there’s neither real nor apparent movement
• Can’t always tell what’s moving
What is real motion?
an object moving through space
what is apparent motion?
something that gives the perception of motion
• Successions of still images can give rise to the perception of motion (animation)
Explain Phi motion
– Perception of motion without intermediate positions
• Looks like single dot jumping back and forth
– Happens at fast switch rates (ISIs)
Explain Beta motion
– Perception of motion with intermediate positions
• Looks like single dot
– Happens at slower ISIs
– Perceptual system ‘fills in’ missing in-between stimuli
– One dot moving smoothly between two locations
how fast do photos in motion pictures run?
24 frames per second
How fast do drawings in animation run?
12 frames per second
How fast do computer rendered images in computer animation run?
Don’t know, it’s all computer generated so there are no frames
Motion sensitive areas appear to be located in the brain where?
in the medial temporal lobe
– Area MT, AKA V5
Define: Akinetopsia
inability to perceive motion, occurs in humans who have lesions near V5
Define: First-order motion
Object motion defined by luminance change
• As the object moves, reflected or projected light changes locally
– i.e. brightness change
Define: Second Order Motion
– Defined by texture change
• Luminance stays the same
• Pattern or texture stays the same
What is involuntary eye movement?
small eye jerks to avoid retinal stabilization
What is voluntary eye movement?
convergent and divergent movements to focus
-tracking a moving object (smooth eye pursuit)
What are saccades?
rapid eye movements to change the location of fixation
Why doesn’t the world jerk around as our eyes move?
Saccadic suppression. The visual system shuts down visual processing during a saccade
What are the 3 pairs of muscles that move the eyes?
– Obliques • Superior & Inferior – Rectus • Superior & Inferior • Medial & Lateral
Why doesn’t the world seem to move when we move our eyes?
A ‘copy’ of the eye movement motor program is sent to a ‘comparator’
– Compares visual scene changes with eye movement changes and compensates perceptual system for retinal image changes caused by eye movements
What is optic flow?
a perceptual flow of object representations around us
Time To Collision and Tau
• As we approach something, it’s retinal projection gets bigger • The ratio of the retinal image size to the rate of its expansion
is Tao
– Provides good estimate of how fast something is
approaching based on fast calculation from retinal image size alone
• Don’t have to know anything about the object
What is sound?
compressed and rarified air radiating away from a vibrating source
What is amplitude?
the height of peaks of sound waves
What is wavelength or frequency?
how close together the peaks (amplitude) are
T/F: Sound travels faster than light
FALSE: Sound travels slower than light, which is why you see lightning before you hear thunder
T/F: Sound travels fastest through less dense substances
FALSE: travels faster through denser substances
T/F: As distance from the source becomes greater, the pressure wave pattern stays the same
TRUE
T/F:Amplitude decreases because the pressure is spread over a larger area
TRUE
What is pressure amplitude?
maximum amount of change from
atmospheric pressure caused by given sound
Name four pure sine wave tones
- 20 Hz
- 27.5 Hz
- 200 Hz
- 261 Hz
- 391 Hz
- 522 Hz
- 1044 Hz
- 4000 Hz
- 5000 Hz
- 10,000 Hz
T/F: We always hear pure sine waves
FALSE: environmental sounds are usually complex tones and are a combination of sine waves
What is Fourier Decomposition?
When a complex waveform is broken back down into its component sine waves
What are the three parts of the ear?
– Outer ear
– Middle ear
– Inner ear
What are the three parts of the outer ear?
• Pinna
– Collects sound and channels down auditory canal • Auditory canal
– Amplifies auditory frequency ranges
– Protects inner parts of ear from exposure • Tympanic membrane (eardrum)
– Boundary between outer and middle ear
What are the two part of the middle ear?
• Bones
– Efficiently translate sound energy from air medium (outer ear) to fluid medium (inner ear)
– Direct air-to-fluid would result in a large amplitude loss
– Solid in-between make more efficient transfer
• Muscles
– Tense in presence of loud sounds – Protects inner ear
What are the structures in the inner ear?
• Cochlea • Three membranes – Reissner's – Tectorial – Basilar • Organ of Corti – Sits on top of basilar membrane – Consists of specialized neurons • Hair cells
What are the three canals in the cochlea called?
– Vestibular canal
– Middle canal
– Tympanic canal
Where does the tympanic canal connect to the vestibular canal?
at the helicotrema
Name the 3 membranes in the inner ear
– Reissner's • Between vestibular & middle canals – Basilar • Between tympanic & middle (bottom) – Tectorial • Between tympanic & middle (top)
What is the cochlea like?
– Rolled-up structure
– Hollow with three channels inside
• Note cross section – Channels filled with fluid
• Vibrating in the presence of sound
Explain the Organ of Corti and what it does
• Contain the Hair Cells called Stereocillia
• The ‘hairs’ of the hair cells
• Rest against (and partially embedded in) the tectorial
membrane
– The axons of the hair cells comprise the auditory nerve
help you hear!
T/F: There are ion channels in the hair cells in the inner ear
TRUE
T/F: The basilar membrane is not flexible
FALSE! It is very flexible, like a bedspread or a tin sheet
How does traveling waves affect the basilar membrane ?
• Air pressure changes are translated via bone & fluid into traveling waves in the basilar membrane
– Air vibrates eardrum
– Eardrum vibrates middle ear bones
– Middle ear bones create waves of vibration in inner ear fluid – Inner ear fluid vibrates basilar membrane, creating wave
What happens to the hair when the basilar membrane moves?
• As the basilar membrane moves it exerts a shearing force on the cilia resting against the tectorial membrane above it
– Membrane up, shears one direction
– Membrane down, shears the other
• Corresponds to phases of the sound wave cycle
– The waves of compressed and rarified air
When the hair cells are at rest, cells are ______ firing
medium
When hair cells are sheared over in one direction, the cells will ____________ firing
increase
When the hair cells are cheated over in the opposite direction, the hair cells will _________ firing.
reduce
What are the cilia of the inner hair cells attached to each other with?
tip links
T/F: There is no such thing as “auditory transduction”
FALSE! Auditory transduction is how the hair follicles in the basilar membrane send signals to the brain
How does auditory transduction work?
• As the hair cells shear, ion channels open and close in the hair cells. allowing K+ and Ca++ to enter the hair cell
• Ion flow changes in hair cells cause de- and hyper-polarization of the hair cells
• Changes firing rate in auditory nerve
– And that’s auditory transduction
T/F: We can perceive frequencies higher than the fastest rate neurons can fire
TRUE!
T/F: Sound waves have phase
true: – Same frequency
– Same amplitude
– ‘up’ and ‘down’ parts of wave are offset in time
T/F: Some neurons respond to specific parts of the waveform
TRUE
The neurons that respond to specific parts of the waveform are called
phase-locked neurons
What is differential phase locking?
when different neurons can respond to different parts of the waveform
T/F: the pattern of firing across a group of neurons can code
any frequency
true
define: distributed representation
a population of
neurons that fire in a pattern
What structures are included in the auditory pathway?
• Cochlear nucleus • Superior olives – Both ipsi- & contralateral • Inferior colliculus – Auditory tectum • Medial geniculate nucleus – Thalamus • Posterior superior temporal gyrus – Cortical area A1
What is the cochlear nuclei used for?
sound onset, (has rapidly adapting neurons ), frequency response sharpening (via lateral inhibition) and some simple relay
What do the superior olives do?
Timing and amplitude differences for sound localization
Transmission fibers from cochlear neuclei & olives travel via the
lateral leminiscus
The inferior colliculus does what?
auditory orienting
What does the Medial geniculate nucleus do?
– Auditory thalamic relay nucleus
– Cortical control of input
What is the primary auditory cortex called?
A1
Where is A1 located?
posterior portion of superior temporal
What do the secondary and tertiary auditory cortexes respond to?
complex sounds
What structures are included in the auditory pathway?
• Cochlear nucleus • Superior olives – Both ipsi- & contralateral • Inferior colliculus – Auditory tectum • Medial geniculate nucleus – Thalamus • Posterior superior temporal gyrus – Cortical area A1
What do the superior olives do?
Timing and amplitude differences for sound localization
What is differential phase locking?
when different neurons can respond to different parts of the waveform
T/F: the pattern of firing across a group of neurons can code
any frequency
true
define: distributed representation
a population of
neurons that fire in a pattern
What is the cochlear nuclei used for?
sound onset, (has rapidly adapting neurons ), frequency response sharpening (via lateral inhibition) and some simple relay
A1 responds to _____ tones
simple
T/F: the auditory pathway is less primitive than the visual system
false, the auditory pathway is more primitive than the visual system
Why does the brain stem have so many nuclei for the auditory system?
Because unlike the visual system that can use retinotopy to provide location information, the auditory system only have the two points (ears) to provide location info, so they need a little extra help
How can we gather location information from timing phase and amplitude?
time onset of a sound will impact ears because the sound will fall on one side of the head sooner than the other, helping your brain locate the sound. The head also acts a buffer, so the amplitude of a sound will be affected traveling from one ear to another.
What does ITD stand for?
Interaural time difference
Define: Interaural Time Difference (ITD)
Difference in onset time is due to the longer distance a sound has to travel to reach the more distant ear
What are the degrees of azimuth?
The measure of how far something is from midline (remember the circle with you in the middle)
MIDLINE = 0
The degrees of azimuth are positive when they are going in ___________ direction
clockwise (up to 180 degrees)
The degrees of azimuth are negative when they are going ___________
counterclockwise (up to 180 degrees)
timing difference works best for what type of sounds?
low frequency sounds, because at high frequency there isn’t enough phase difference to detect
Amplitude difference works better for what type of sounds?
High frequency sounds
What does ILD stand for?
Interaural Level Difference
Define Interaural Level Difference
the ability for the head to muffle the sound from a source on the opposite side of the head
Sounds on the ___ have no ILD
midline
ILD: If the sound if off the midline, then the sounds will be lower amplitude at the ear on the _________ side of the head from the sound
opposite
The _______ the degrees of azimuth, the greater the ILD
greater
ILD works best for ________ frequencies
higher
Where is the first place in the brain that has binaural input?
the Superior Olives
Where is the ITD computed in the Superior Olives?
the medial superior olivary nucleus
Where is the ILD computer in the Superior Olives?
the lateral superior olivary nucleus
The cone of confusion is what?
places in space where all sounds are produced at the same time and density between both ears. (0 degrees, 60 degrees, 90 degrees and 120 degrees)
Why aren’t the ILD curves exactly the same at the 60 & 120 degree levels?
because the ears aren’t shaped the same at the front
and back
What are the functions of the Pinna?
– Funnel sound down the ear canal – Change the amplitude of sounds • Front to back – Reduces front to back ambiguity • Top to bottom – Reduces top to bottom ambiguity
What is the auditory equivalent to the “haze” effect in vision?
The low and muffled sounds something makes when it is far away from you
T/F: Sounds can come from multiple directions?
True!
T/F: Sounds from close sources have a greater chance to
bounce off of things
False, they have less of a chance to bounce off things. Sounds far away have a greater opportunity to bounce off objects.
T/F: Owls and Cats both make “maps” of an area by its sounds so they can locate prey
True
The mapping in A1 is _______
tonotopic
What is happens during tonotopic mapping?
Frequencies close to each other are coded next to each other on the basilar membrane, Projection fibers stay next to each other through the auditory system, Frequencies (sound pitches) close to each other are represented close to each other in the brain. EVERYTHING STAYS CLOSE TOGETHER
T/F: A2 neurons respond better to complex stimuli
TRUE
Explain what RSVP is
– Present stream of items, one at a time, at fixation, very
quickly (e.g. one every 100 ms)
– Make items distinct from one another (e.g. letters and
numbers)
– Have participants respond to one category of the items (e.g.
the numbers) while ignoring the others
T/F: The differences that occur during an instance of change blindness can be fairly large and important, yet we often fail to perceive them.
TRUE
____________ is fixing your eyes on one thing but attending to another thing in your surroundings without actually moving your eyes
covert attention
Reading a book but being aware that there are peopling talking around you in a coffee shop is an example of
Divided attention
Watching the pot to note the exact moment that the water starts boiling is and example of
sustained attention
Picking one of few stimuli out of many stimuli is called
selective attention
Define: response enhancement
an effect of attention on the response of a neuron in which the neuron responding to an attended stimulus gives a bigger response. Example: making a cell more responsive across the board because it is maximally responsive to vertical lines
Define: sharper tuning
when a cell becomes more precisely tuned, and would make it easier for a neuron to find a weak vertical signal amid the noise
What kind of problems do people face when they have a lesion in the right parietal lobe?
they have problems directing attention to objects and places on their left
What is neglect?
Neglect is a disorder that is characterized by patients believing that part of the world is not there. If asked to explain something in the left visual field, patients will explain objects to the right and ignore the left.
What is extinction?
when you can visually attend to something in either right or left field of vision, but if there is something in both of them, you can’t see the stimulus in the ipsilesional field
What is simultagnosia?
The inability to perceive more than one thing at a time
What are some symptoms of Balint syndrome?
- spatial localization abilities are greatly reduced, patients can’t reach for things very well
- patients with this disorder don’t move their eyes much, they usually stare ahead
- they behave as if they can only see one object at a time
an example of inattentional blindness, (when a stimulus that would be easy to recognize if it was being attended to) is
the gorilla / basketball experiment.
