Exam #3 Flashcards
Spatial suppression
Increasingly difficult identification of motion direction with increasing size of moving stimulus (larger=harder to see)
Spatial summation vs suppression at different contrasts
- Summation: low contrast
- Suppression: high contrast
“Impaired” performance in spatial suppression
- Seeing high contrast:
- YA: “typical”, can’t see it, has high spatial suppression (bad)
- Older adults, depression, SZ, autism: “impaired”, can see it, has less spatial suppression (good)
How does TMS produce “virtual lesions”?
Temporarily removes “break” in MT (“turn off”)
Suppression index
Large stimulus threshold- small stimulus threshold
What is suppression critical for?
Perceptual processing
-we have A LOT of sensory input so we need to limit it (relevance)
Levels of visual perception (3)
- Low level (simple visual sensations): V1
- Mid-level (basic visual properties): Extrastriate visual areas
- High-level (complete visual perception and recognition): Extrastriate visual areas
Parietal pathway
- Dorsal stream
- “where”
- action, how, spatial visual
Temporal pathway
- Ventral stream
- “what”
- perception, object recognition
Ventral
Object perception and recognition
Dorsal
Locations, directions, interaction with objects
Partial lobe damage yields
- Intact object perception
- Impaired “time/space” perception
Temporal lobe damage
- Impaired object perception
- Intact “time/space” perception
Akinetopsia
Lose ability to perceive motion (pouring liquid)
Visual neglect
Stroke interrupts blood flow to right parietal lobe, failure to acknowledge objects presented contralateral to lesion
Optic ataxia
Deficit in reaching under visual guidance that cannot be explained by motor, somatosensory, visual field deficits, or acuity deficits
Apperceptive agnosia
Deficit in perceptual processing (ex: can’t distinguish shapes, can’t copy picture), more severe, parietal lobe damage
-Can’t perceive or recognize
Associative agnosia
“Normal” perceptual processing, but deficit in linking percept to name (ex: can describe visual scene but fails to recognize them, can copy picture)
-Can perceive, but not recognize
Prosopagnosia
Inability to recognize familiar faces
Color agnosia
Good color vision, inability to recognize colors or assign colors to objects (temporal lobe damage)
Viewpoint invariance
Ability to recognize object regardless of viewpoint
Similar images fire similar cells in _____, but different cells in _____.
- V1
- IT
Different images fire different cells in _____, but same cells in _______.
- V1
- IT
Structural description models
Small set of primitives can specify large set of objects (recognition by components), geons–> objects
View based models
Maintain a memory of many different views for each object we need to recognize (can identify 3D objects from 2D viewpoints)
Where are faces processed in the brain?
FFA, can increase with expertise
Where are places processed in the brain?
PPA (parahippocampal place area)
Is attention top-up or bottom-up processing?
Bottom-up
Covert attention
Gaze is peripheral, move eyes, top-down, resource demanding
Overt attention
Gaze is in direct focus, bottom-up, occurs with few resources required
Exogenous shifts are elicited by…
External stimulus (ex: bright flashes, loud noises)
Endogenous shifts are…
Internally driven (ex: visual search, auditory search)
Bottleneck
A restriction on the amount of info that can be processed at once forcing serial processing
Limits of attention (3)
- Amount of info coming from optic nerve (500 10 megapixels jpegs per sec)
- Processing massively parallel=serial bottlenecks
- Lots of energy to keep brain running
Inattentional blindness
Lack of attention, missing conspicuous events (ex: gorilla video)
Change blindness
Change in visual stimulus that is missed
Attentional blink
Second of two targets cannot be detected or identified when it appears close in time to first target
Visual search
Lower target prevalence = higher % of targets missed
Feature search
Bottom-up, active scan of visual environment for particular object among others
Conjunction search
Similar to feature search, combo of features, harder and slower
Hemispatial neglect
(see visual neglect), stroke interrupts flow to right parietal lobe, failure to acknowledge objects in field contralateral to lesion (ex: drawing half of flower)
Sound pitch
Subjective experience associated sound frequency
Sound loudness
Subjective experience associated sound intensity
What is audibility curve used for?
Determining what frequencies an individual is most sensitive to
Why are fingernails on chalkboard so annoying?
Activates amygdala, similar to monkey warning calls
Tibre
AKA sound quality: when 2 sounds are heard that match for pitch, loudness, and duration, a difference can still be heard (ex: musical instruments)
Amplitude envelope
Changes in amplitude of sound over time, affects timbre, allows us to effortlessly identify sounds
What is the inner ear responsible for?
Frequency analysis
What is the inner ear composed of?
Cochlea
What is the middle ear responsible for?
Impedance matching and sound gating
What is the middle ear composed of?
Stirrup, anvil, hammer, eardrum
What is the outer ear responsible for?
Sound pickup and amplification
What is the outer ear composed of?
Ear canal
Impedance matching
Ear drum picks up weak vibrations over a large area, ossicles act like a lever system and concentrate movements to more forceful vibrations over a smaller area of oval window, can displace oval window against cochlear fluid
Sound gating
Muscles in middle ear are able to reduce the transmission efficiency of ossicles in order to protect the inner ear from loud noise
Pre-programmed response
Muscles contract before you speak
Reflexive response
Muscles contract after a sustained loud noise such as a rock concert
Is the base or the apex of the cochlea wider?
Apex, but stiffness decreases from base to apex
What does the round window do?
Displaces the basilar membrane, fixes problem of membrane being surrounded by fluid and not able to be compressed (acts as pressure release outlet=allows oval window to move)
Where is sound frequency topographically represented?
Basilar membrane (place coding)
Characteristic frequency of auditory neurons
Frequency at which neuron is most responsive- from cochlea to cortex
Interaural intensity difference best at what frequency of sounds?
High frequency, your head is a good obstacle for high freqs.
Interaural time difference best at what frequency of sounds?
Low frequency, slight delay for sound to get from right to left ear, better for low freq.
What does the pinna do?
Filters sound, filtering depends on sound direction
Direct sound
Sound that reaches the listeners’ ears straight from the source (ex: outside)
Indirect sound
Sound that is reflected off of environmental surfaces and then to the listener (ex: inside)
Precedence effect
Listeners make localization judgments based on earliest arriving waves in onset of a sound (because of reverberation)
