midterm 1 Flashcards
Why is it so difficult for us to design a computer program that can identify objects as fast and accurately as we can (2)
Our brains allow us to classify objects very quickly;
This is very difficult to code for in computer programs, making it difficult for computers to categorize and identify objects
Why do people sometimes see/hear/feel different things when attending to the same stimuli
constructed and often somewhat subjective nature of perception
Sometimes the things we see/hear can be affected based on
{{c1::priming}}
Perceptual processing generally involves:
A __ stimulus
Processing at the ___ level (ie transduction)
Processing at the ____ level
__ processing that gives rise to particular interpretation/meaning
Some accompanying___ response (eg. action)
{{c1::distal}}
{{c1::receptor}}
{{c1::neuronal}}
{{c1::Top down}}
{{c1::behavioral}}
Objects _ the horizon (an imaginary horizontal line that is at the same level as the observer or ‘eye level’) that are higher in the field of vision are more distant
below
Objects above the horizon that are __ in the visual field are more distant
lower
object ID problem demonstrates the complexity of __ and associated__ and speaks to its constructed nature
{{c1::perception}}
{{c1::ambiguities}}
_ _ _ demonstrates the complexity of perception and associated ambiguities and speaks to its constructed nature
object ID problem
Any information the perceiver brings to a situation can be referred to as
{{c1::knowledge}}
__ is based on incoming stimuli from the environment
Sometimes referred to as ___ processing
{{c1::Bottom up processing}}
{{c2::data-based}}
___ Processing based on the perceivers previous knowledge (ie cognitive factors)
Sometimes referred to as ___
{{c1::Top down processing }}
{{c2::knowledge based processing}}
__receptors are cells specialized to respond to environmental energy(e.g. with vision, a critical element involves visual pigments reacting to light)
___ is then said to occur, which converts environmental energy into__ impulses during__ processing
Sensory
Transduction
nerve
receptor
___processing involves changes that occur as signals are transmitted through the mess of neurons in our brains
e.g. different primary receiving areas for different modalities
Neural
perceptual process order (DLR NPRA)
- distal stimulus
2 light reflected and focused
3, receptor processes - neural processing
- perception
- recognition
- action
three general kinds of perceptual relationships:
Stimulus -> Behaviour
Stimulus -> Physiology
Physiology -> Behaviour
Orientation of more _ spaced lines easier to accurately identify than _ spaced
Accurate identification of the orientation of the lines eventually becomes impossible as spacing gets sufficiently _
what type of perceptual b is this?
Orientation of more widely spaced lines easier to accurately identify than narrowly spaced
Accurate identification of the orientation of the lines eventually becomes impossible as spacing gets sufficiently close
Stimulus -> Behaviour
what relationship is this: Neural response changes in predictable ways when perceiving lines of different orientations
Stimulus -> Physiology
For horizontal and vertical orientations:
Identification is better (the oblique effect)
These stimuli result in greater neural activation
what type of perceptual b is this
Physiology -> Behaviour
oblique effect
can ID horizontal and vertical lines better
Why is the difference between physical and perceptual properties important?
One reason is because they are not always equivalent!
Response Compression
as intensity increases, the perceived magnitude increases more slowly than the actual increase in intensity
example of Response Compression
(e.g. can occur with brightness perception)
Response Expansion:
as intensity increases, the perceived magnitude increases more quickly than the actual increase in intensity
example of response expansion
(e.g. can occur with pain perception)
distal stimuli
Environmental stimuli are all objects in the environment that are available to an observer
proximal stimuli
the images formed on the retina
When an observer selectively attends to an object, receptors respond to the distal stimulus, resulting in the generation of internal representations
Principle of Representation
Everything a person perceives is based not on direct contact with stimuli but rather on representations of stimuli that are formed on the receptors and the resulting activity in the person’s nervous system
Principle of Transformation
The representations of stimuli in our environment which we construct are transformed, or changed, between the original distal stimulus and the eventual perception they give rise to
Energy can be described using__ (measured in nm: nanometers)
The electromagnetic spectrum spans a huge range, from short wavelength__ rays to long wavelength___ waves
The visible spectrum for humans ranges from ___, which we perceive as ‘colour’
wavelength
gamma, radio
400 to 700 nm
Most perceived light is__ light
reflected
Light enters the eye through the__ and is focused by the__ and lens to a sharp image on the__
pupil, cornea, retina
__ and __ are visual receptors in the retina that contain visual pigment
Rods and cones
The optic nerve carries information from the__ toward the brain
retina
___work similarly to the eye and can be a useful point of comparison
Cameras
The eye has ~__ million rods and ~__ million cones,
120M, 6M
rods and cones differ in:
Shape
Rods: Cones:
Distribution across the retina
Fovea consists solely of _
Peripheral retina is mostly _ (but also contains some _)
Shape
Rods: large and cylindrical
Cones: small and tapered
Distribution across the retina
Fovea consists solely of cones
Peripheral retina is mostly rods (but also contains some cones)
Macular degeneration: _ and small surrounding _ are destroyed (has particular implications for _ acuity vision)
Creates a ‘dead zone’ on the _
Most common in _ individuals
Fovea and small surrounding area are destroyed (has particular implications for high acuity vision)
Creates a ‘dead zone’ on the retina
Most common in older individuals
Retinitis pigmentosa: _ are destroyed first (has particular implications for _ vision)
Foveal cones can also be attacked
Linked to genetic/environmental causes
Severe cases can result in complete _
Retinitis pigmentosa: Rods are destroyed first (has particular implications for night vision)
Foveal cones can also be attacked
Linked to genetic causes
Severe cases can result in complete blindness
Problems with Receptors
Macular degeneration
retinitis pigmentosa
The location where the optic nerve exits the eye contains no receptors
blind spot
blind spot
The location where the optic nerve exits the eye contains no receptors
do/don’t notice blind spot
why? (3)
do
One eye covers the blind spot of the other
It is located towards the edge of our visual field
The brain ‘fills in’ missing information by extrapolating what’s around it (via top-down processing)
The cornea, which is fixed, accounts for about__% of the focusing power of our eye
The lens, which adjusts shape for object distance, accounts for the other__%
We can typically see far away objects relatively clearly when our lenses are___, though not near objects
80
20
relaxed
Accommodation
occurs when ciliary muscles are tightened
Accommodation causes the lens to__
Light rays then pass through the lens more___, allowing for near objects to be focussed on the retina and thus forming a clearer image
thicken
sharply
Myopia (AKA ‘nearsightedness’) refers to the inability to see__ objects clearly
Occurs when the image gets focused ____ of the retina
distant
in front
myopia can be caused by
Refractive myopia
Axial myopia
Refractive myopia:
Axial myopia:
Refractive myopia: cornea or lens bends too much light
Axial myopia: eyeball is too long
Hyperopia (AKA ‘farsightedness’) refers to the inability to see__ objects clearly
Occurs when the image gets focussed__ the retina
Usually caused by an eyeball that is too__
nearby
behind
short
Constant accommodation for hyperopia for nearby objects can lead to___ and___
eyestrain
headaches
Presbyopia (AKA ‘old eye’) occurs when __
Caused by hardening of__ and weakening of ___
Corrective___ are needed for close activities, such as reading
the lens can no longer adjust for close objects
lens, ciliary muscles
lenses
The outer segments of receptors contain visual pigment molecules, which consist of two components:
retinal, opsin
Retinal:
opsin
Retinal: a light sensitive molecule
Opsin: a large protein
Visual transduction
occurs when the retinal absorbs one photon, causing it to change shape (a process referred to as isomerization)
In total, the isomerization of a single visual pigment molecule activates about __ million other molecules, a cascade of effects which eventually results in the activation of the___
1
receptor
Dark adaption refers to the
process of increasing visual sensitivity after switching from high to low-level lighting conditions
dark adaptation curve can be determined using the following general approach:
steps 1-3
- An observer starts in a lit room and becomes ‘light adapted’
- The lights are then turned off, at which point the observer adjusts the intensity of a test light until it is just barely visible. This determines their sensitivity at the beginning of the dark adaptation curve
- As time passes, they continue to readjust the intensity of the test light (again, until it is just barely visible) to plot the change in sensitivity across time
how was dark adaptation curve measured for both rods and cones
looking directly at a fixation point while (covertly, without moving the eye) attending to a test light off to the side
results for dark adaptation curve that measures both rods and cones
- sensitivity increases in _ stages
Stage one takes place for _ to _ minutes
Sensitivity then levels off for seven to ten minutes (the - break)
Stage two shows increased sensitivity for another _ to _ minutes
2
Stage one takes place for three to four minutes
Sensitivity then levels off for seven to ten minutes (the rod-cone break)
Stage two shows increased sensitivity for another 20 to 30 minutes
are rods or cones more sensitive to peripheral light
rods
how was cone dark adaptivity tested
what were the results
which stage of dark adaptivity results indicates this
Participant fixates directly on test light
Results show that sensitivity increases for three to four minutes and then levels off
first stage
why did participants look directly on test light for cone dark adaptivity testing
This stimulates (and thus isolates the effect of) only cones, because that is the only kind of receptor in the fovea
how was rod dark adaptivity tested
what were the results
which stage of dark adaptivity results indicates this
Accomplished by using a rod monochromat participant
Results show that sensitivity increases for about 25 minutes and then levels off
The second stage of the dark adaptation curve can be attributed to this
why was a rod monochromat used for rod dark adaptivity
to isolate effect on rods
process for transduction
_ molecule changes shape
Opsin molecule _
The retina shows visual pigment _
Retinal and opsin must then recombine in a process called _, in order to be capable of responding to light again
retinal molecule changes shape
Opsin molecule separates
The retina shows visual pigment bleaching
Retinal and opsin must then recombine in a process called regeneration, in order to be capable of responding to light again
Pigment bleaching accounts for being ….
because your entire supply of pigments is _ and must _ before _ can occur again
temporarily ‘blinded’ by a bright light (e.g. camera flash)
your entire supply of pigments is depleted and must regenerate before transduction can occur again
gradual improvement that we experience as we dark adapt has a lot to do with
pigments being regenerated at a faster rate than they’re being used
Spectral sensitivity refers to
Monochromatic light (_____) can be used to determine ____ at different wavelengths
the sensitivity of rods and cones to different parts of the visible spectrum
Monochromatic light (containing only one ‘type’ of wavelength, e.g. 400 nm) can be used to determine threshold at different wavelengths
Threshold and sensitivity are
reciprocal
Humans are most sensitive to the _ part of the visible spectrum (/ light)
This corresponds to the part of the spectrum that they have the lowest/highest threshold for
Humans are most sensitive to the middle part of the visible spectrum (greenish/yellow light)
lowest
Rods and cones are similar/differ in their spectral sensitivity
differ
Rods are more sensitive to _-wavelength light (most sensitivity at 500 nm)
Cones are most sensitive at _ nm
Rods are more sensitive to short-wavelength light (most sensitivity at 500 nm)
Cones are most sensitive at 560 nm on average
The difference in spectral sensitivity across rods/cones is due to a
difference in their absorption spectra of visual pigments
Purkinje shift:
enhanced sensitivity to short wavelengths during dark adaptation when the shift from cone to rod vision occurs
purkinje shift results in
Results in blue ‘seeming’ brighter to a dark-adapted eye, as compared to how it appears to a light-adapted eye (and can also shift our perception of colour)
Rods and cones send signals vertically through: (2)
Bipolar cells
Ganglion cells
Signals are sent horizontally: (2)
Between receptors by horizontal cells
Between bipolar and between ganglion cells by amacrine cells
_ million rods and cones converge to 1 million _ cells
Higher/lower convergence of rods than cones
Average of _ rods to one ganglion cell
Average of _ cones to one ganglion cell
Cones in fovea have - relation to ganglion cells
126 million rods and cones converge to 1 million ganglion cells
Higher convergence of rods than cones
Average of 120 rods to one ganglion cell
Average of six cones to one ganglion cell
Cones in fovea have one to one relation to ganglion cells
Rods (as compared to cones)… (3)
Are more sensitive to light, Take less light to respond, greater convergence
greater convergence of rods results in…
trade off?
summation of the inputs of many rods into ganglion cells, increasing the likelihood of a response
rods cannot distinguish detail as well
more convergence of rods = more/less sensitive
more
compared to rods are cones sensitive enough to register a response to a faint stimulus
no
All-cone foveal vision results in __ _ _
This relates to the difference in convergence, in which more/fewer cones are connected to any one ganglion cell (i.e. have more/less convergence)
T/F: This kind of wiring allows cones to better discriminate detail (as compared to rods)
high visual acuity
fewer, less
T
The trade-off for cones due to wiring
need more light to respond than rods
explain firing pattern of ganglion that’s connected to multiple roods when it is stimulated in two different patterns
explain firing pattern of ganglion that’s connected to one cone when it is stimulated in two different patterns (1:1 connection)
same firing pattern in ganglion, cell can’t differentiate
different firing pattern that can be differentiated
different firing pattern of cones indicate
greater acuity
t/f: humans can perceive uv like bees
f
Visual receptive fields refer to the
retinal region over which a given cell in the visual system can be influenced (excited or inhibited) by light
visual receptive fields Can be determined by monitoring
single cell responses
single cell responses
They cover a greater/smaller area than that associated with a single rod/cone, and do/do not overlap with each other
(stimulus is presented to retina and response of cell is measured by an electrode)
greater, do
hartline based work of single cell responses on
frog eyes
unlike frog eyes, cat (and human) eyes can demonstrate both _ and _ effects associated with receptive fields
excitatory and inhibitory
2 basic forms of retinal vision
Excitatory-centre-inhibitory surround
Inhibitory-centre-excitatory surround
Output of centre-surround receptive fields changes depending on area stimulated:
Highest response when only the___ area is stimulated
Lowest response when only the___ area is stimulated
Intermediate responses when both areas are stimulated (- antagonism)
excitatory
inhibitory
centre-surround
implication of excitatory-inhibitory layout of eye
neural mechanism that allows the neuron to respond ‘best’ to one particular type of stimuli
excitatory-inhibitory layout of eye demonstrates
‘tuning’, or specialization for a particular kind of stimulus
Signals from retina exit the eye through the _ _ then…
Arrive first at the __
sent along to the _ in the_ lobe
Are then sent through two pathways to the_ lobe and the_ lobe (the dorsal and ventral streams)
And finally arrive at the_ lobe
optic nerve
lateral geniculate nucleus (LGN)
primary visual receiving area, occipital
temporal, parietal
frontal
primary visual receiving area located in
striate cortex, beginning with area V1
_ _ also receives some signals form the eye and and is important for controlling -
Accounts for ~_% nerve fibres leaving the eye
superior colliculus
eye-movements
10
The __accounts for ~ 90% nerve fibres leaving the eye
LGN
LGN cells have ___ (like in the retina)
centre-surround receptive fields
More ‘information’ (a larger signal) is sent from the eye to the LGN, as compared to what is passed along from the LGN to_
what does this suggest?
V1
(suggesting the LGN may regulate, or filter, what information is passed along to V1)
The LGN also receives more/less information from the cortex than it sends to the cortex
what does this suggest?
more
backward flow of information that may constitute a feedback mechanism
Neurons that fire in response to specific features of a stimulus are called
feature detectors
feature detectors have receptive fields with both _ and _ areas (like the receptive fields in the retina and LGN)
They are oriented _ - _ (rather than the centre-surround receptive fields seen in the retina and LGN)
inhibitory and excitatory
side-by-side
Major types of feature detectors in V1: (3) (sec)
Simple cortical cell
Complex cortical cell
End-stopped cortical cell
___ plot the response of a simple cortical cell to line stimuli of varying orientations
Orientation tuning curves
Complex cortical cells
respond best to movement across the receptive field of particularly oriented bar
what happened when Hubel and Wiesel dropped a slide into their slide projector, the image of the edge of the slide moving down
triggered activity in complex cortical cells
simple cortical cells
excitatory and inhibitory areas arranged side by side, responds best to particular orientation
end stopped cortical cells
responds to corners, angles, bars of a particular length moving in a particular direction
optic nerve fibre (ganglion cell)
center surround receptive system
responds best to small spots but will recognize other stimuli
selective rearing and selective adaptation are examples of what relationship
physiology -> behaviour
Absolute Threshold:
how to determine this??
smallest amount of energy needed to detect a stimulus
Method of Limits
how does method of limits work:
Present stimuli of _ intensities in ascending and descending order
Record whether the stimulus can be_ on each trial
Average the - point
different
perceived
cross-over
cross-over point
point where stimulus goes from being perceived to not being perceived
a phenomenon in which neurons tuned to specific stimuli properties fatigue with prolonged exposure to stimuli containing those properties
Selective Adaptation
Fatigue or adaptation to stimulus causes a decrease in both:
Baseline firing of those neurons
The response of those neurons to repeated presentations of the stimuli they have been adapted to
In this context ’selective’ means that only those neurons that respond to the specific stimulus property being tested adapt, which provides a way to selectively modulate activity of specific neurons
for example…?
e.g. feature detectors tuned to respond to vertical lines will fatigue when shown lots of vertical lines, but other features detectors should be unaffected
The typical stimuli used for selective adaptation are called_ and are made of alternating light and dark bars
Angle relative to vertical can be changed to test for sensitivity to_
Difference in intensity can be changed to test for sensitivity to_
gratings
orientation
contrast
General experimental procedure for testing selective adaptation (just list the 3 steps) MAR
- Measure sensitivity to range of one stimulus property
- Adapt neurons with extended exposures of stimuli of property being tested
- Remeasure the sensitivity to range of that same stimulus property
selective adaptation steps in full:
1. Measure sensitivity to range of one stimulus property (e.g. orientation), which can be taken as your ‘baseline’ response
- Determine _ _ by decreasing intensity of grating until person can just see it
- Calculate the _ _ (sensitivity = 1/threshold)
2. Adapt neurons with extended exposures of stimuli that have the_ being tested
3. Remeasure the sensitivity to range of that same _ property
contrast threshold
contrast sensitivity
property
stimulus
selective adaptation experiments allows us to make what type of claims?
causal
Selective rearing refers to
raising animals in environments that contain only certain types of stimuli (while depriving exposure to other kinds)
Blakemore and Cooper (1970) manipulated whether kittens were raised in environments with (only) either horizontal or vertical lines and saw that kitties ____
Effects apparent in both __ and __ responses
raised in an environment of all vertical lines couldn’t perceive horizontals, and vice versa
behavioural, neural
In theory, neurons that respond to whatever stimuli are present in the environment will become more__ due to _ _
this can explain the __ effect
predominate
neural plasticity
oblique
The organization of V1 represents an ‘electronic map’ of the retina which is __
retinotopic
retinotopic:
two points that are close together on an object (and thus are also close together on the retinal image formed by looking at the object) are also represented in parts of the cortex that are close together
Cortical Magnification: __
This is one of several mechanisms that contribute to _ - _ vision
Similar to how less convergence of cones helps with this at the receptor level, this is one mechanism that accomplishes something similar at the level of the _
a small area of the fovea is represented by a large area on the visual cortex
high-acuity
cortex
cortical magnification
region that takes up less space in the visual field yet takes up more space in the cortex
blood flow increases/decreases to active areas of the brain
blood flow provides __ about brain activity
hemoglobin contains __ that has __ properties
increases
correlation
ferrous, magnetic
As active neurons ‘use up’ oxygen in the nearby supply of blood, this makes the hemoglobin more/less magnetic and changes it’s response to the magnetic field
fMRI can estimate changes in the activity level of specific areas of the brain by detecting changes in the _ response of hemoglobin to the _ field
more
magnetic, magnetic
single-cell recordings
which measure firing of individual neurons
Neuroimaging allows us to move beyond _ - _ _ and look at the distributed pattern of activity in the _ in response to stimuli as a whole
single-cell recordings
cortex
Lesioning or ablation experiments (steps 1-4)
- An animal is trained to indicate perceptual capacities
- A specific part of the brain is removed or destroyed
- The animal is retrained to determine which perceptual abilities remain
- The results reveal which portions of the brain are responsible for specific behaviours
Object discrimination problem:
Landmark discrimination problem:
Object discrimination problem: Monkey is trained to look in the food well under a specific object
Landmark discrimination problem: Monkey is trained to look in the food well next to a specific object
Monkey is trained to look in the food well under a specific object
Monkey is trained to look in the food well next to a specific object
Object discrimination problem:
Landmark discrimination problem:
Ungerleider and Mishkin: using ablation, part of the _ lobe was removed from half the monkeys and part of the _ lobe was removed from the other half
parietal
temporal
Ungerleider and Mishkin
Removal of temporal lobe tissue resulted in problems with the __ (implicating the _ pathway, or _ stream), though not the _ task
object discrimination task
what, ventral
LD
Ungerleider and Mishkin
Removal of parietal lobe tissue resulted in problems with the __ task (implicating the _ pathway, or _ stream), though not the _ task
landmark discrimination
where, dorsal
OD
The dorsal and ventral pathways demonstrate a classic _ _:
what other areas demonstrate this
double dissociation
Broca and Wernicke’s area represents another well known example of a double dissociation
double dissociation
two functions that involve different mechanisms and operate independently
damage to broca’s area typically leads to what but NOT what
wernicke’s area?
language production but not comprehension
comprehension but not language production
Both the ventral and dorsal pathways:
Originate in the __ and continue through two/three different types of ganglion cells in the _ (_ and _)
Have some _
Receive feedback from _brain areas
retina, two, LGN, magnocellular, parvocellular
interconnections
higher
parvocellular neurons are more sensitive to
colour and fine detail
dorsal stream may be more accurately described as the ‘_’ pathway, reflecting it’s role in action compared to its original role in the _ pathway
how, where
Dorsal stream shows function for both _ and for _
location, action
Ganel experiment was designed to demonstrate a separation of perception and action in ‘healthy’ subjects (i.e. without brain damage); Two conditions: passive length estimation vs. grasping length estimation
what were the results and implications
results: thought lines were same size when doing passive length estimate but grasping lines helped them realize lines were two different lengths
implications: we use different parts of our brains, that might affect our experimental results/how we test things in experimental context
as the signal originating from the eye continues to get routed through various neural pathways, the complexity of what the neurons in those regions of the brain respond to increases/decreases
increases
signal pathway for vision starting with LGN
which one responds to most complex one?
lgn - v1 - v2 - v4 - it
it
gross et al accidentally discovered that _ best responds to hand like features
it
FFA best responds to
things that resemble faces
_ - _ plasticity in humans can exert a strong effect on perception
Experience-dependent plasticity
training areas of teh FFA can result in it…
implications?
responding to those objects as well
implies that FFA might not be hardwired exclusively for faces
Signals coming from IT cortex project to
MTL
Medial temporal lobe (MTL) structures are extremely important for__ (e.g. parahippocampal cortex, entorhinal cortex, hippocampus)
memory
what did quiroga et al favour in the experiment where they removed part of a pt’s brain to stop seizures and then checked neuron activity when shown photos and drawings of different famous people
difference in brain activity is connected to memory
- We seem to process faces __
- may involve some dedicated neural mechanisms, or _, that are specialized for processing particular kinds of stimuli
evidence (2)
holistically
modules
have trouble processing upside down faces with different features; prosopagnosia
prosopagnosia
occurs when there’s damage to
inability to perceive faces
temporal lobe
_ _ are strong for faces, and are said to occur for stimuli that people have easy time/difficulty noticing unusual details (anomalies) in when turned upside down
Inversion effects
difficulty
_ _ refers to the way perceived objects are represented through neural firing
Sensory coding
Sensory coding
the way perceived objects are represented through neural firing
3 theories of how sensory coding of complicated objects are accomplished
Specificity Coding
Population Coding
Sparse Coding
Specificity coding:
aka _ __ hypothesis
specific (individual) neurons respond to specific stimuli
grandmother cell
Population coding:
pattern of firing across many neurons codes specific objects
Sparse Coding:
only a relatively small number of neurons are necessary to code for each concept/identify, etc.
_ _ problem refers to the task of determining the object responsible for a particular image on the retina
inverse projection
_ are common in the environment and objects are often partially hidden or obscured
Occlusions
T/F: Resolving these ambiguities (seeing objects from different pov) can prove to be easy task for computers to perform
f
_ _ allows things to be recognized as equivalent from different perspectives
viewpoint invariance
viewpoint invariance allows
things to be recognized as equivalent from different perspectives
Structuralism: took a _ view of psychological processes and broke down a complex compound into it’s constituent _
Established by _
Viewed perception as _ combinations of various basic _
reductionist, elements
Wundt
additive, sensations
_: a school of thought that rejected the structuralist approach
Viewed perception as a product of the mind grouping patterns according to _ of _ _
Gestalt
laws of perceptual organization
phi phenomenon (AKA apparent motion
occurs when still images are perceived as being in continuous motion when rapidly alternated across different locations
easily recognizable objects tend to be seen as complete, even if parts may be absent (particularly when borders/edges, etc. are ‘implied’)
Illusory Contours (AKA law of closure):
: lines tend to be seen as following the smoothest path possible
Principle of Good Continuation
every stimulus pattern is seen in such a way that the resulting structure is as simple as possible
Principle of Pragnanz (principle of good figure, or simplicity):
similar things tend to be grouped together
Principle of Similarity
things that are close together in space tend to be grouped together
Principle of Proximity
objects moving in the same direction tend to be grouped together
Law of Common Fate
elements in the same region tend to be grouped together
Common Region
connected region of visual properties are perceived as single unit
Uniform Connectedness
t/f: Several of gestalt principles can factor into how things are perceived at once
T
_ _ influence perceptual segregation of figure from ground
Areas lower/higher in the field of view are more likely to be perceived as a figure
Figural cues
lower
Convex/concave regions (i.e. that ‘bulge’ outward) more likely to be perceived as figure
convex
can there be situations that override gestalt experiences?
yes
t/f: Sometimes perceptual organization operates very rapidly, while other times it can emerge more slowly
t
a scene is acted _
an object is acted _
within
upon
masking
random pattern that is flashed onscreen immediately after a stimulus presentation, used to prevent persistence of vision that can facilitate further processing after the image has disappeared
Five global image features of scenes that are perceived rapidly and holistically (NO REC)
Degree of naturalness:
Degree of openness:
Degree of roughness/smoothness:
Degree of expansion:
Colour:
environmental physical regularities relate to _ _ which is a product of _ - _ plasticity
oblique effect
experience-dependent
light comes from above in the natural (and many unnatural) environments; leads to this assumption
Light-from-above assumption
characteristics associated with the functions carried out in different types of scenes
semantic regularities
semantic regularities
characteristics associated with the functions carried out in different types of scenes
the knowledge of what a given scene ordinarily contains
scene schema
scene schema is
the knowledge of what a given scene ordinarily contains
results of palmer’s experiments regarding scenes:
Targets congruent with the context were identified _% of the time
Targets that were incongruent were only identified _% of the time
80
40
explains some of our perceptions as the result of unconscious assumptions and inferences we make about the environment based on our prior knowledge and personal history of experiences (i.e. top-down mechanisms)
Helmholtz’s Theory Of Unconscious Inference
: we perceive the world in the way that is “most likely” based on our past experiences
Likelihood Principle
Thomas Bayes (1701-1761) developed _ _, in which estimates of the probability of a given outcome are influenced by two factors:
Bayesian Inference
The prior probability
The likelihood of a given outcome
The prior probability
The likelihood of a given outcome,
(our initial belief about the probability of an outcome)
the extent to which the available evidence is consistent with the outcome
Evidence from humans using fMRI show:
Fusiform face area (FFA) responds best to…
Parahippocampal place area (PPA) responds best to…
Extrastriate body area (EBA) responds best to pictures of …
faces
spatial layout
full bodies and body parts
Refers to stimuli causing neural activity in a number of different areas of the brain
Activity is _ across the brain
Distributed representation:
distributed
T/F: Although it may appear contradictory on the surface, distributed representation and localization of function can be compatible/complimentary
T
how did ishai et al prove distributed representation and localization of function can be compatible/complimentary
distributed rep: specific stimuli categories activated different parts of cortex
localization: different locations were activated depending on stimuli presented
huth et al showed participants different pics and measured brain activity, saw that multiple points across the cortex are coded as belonging to the same category of stimuli (e.g. humans)
what does this suggest
some kinds of stimuli are processed in more than one location
we may process various properties of the same stimuli in different areas of the brain
: the PPA responds to the surface geometry or the geometric layout of a scene and thus can be activated by any stimuli that produces a sense of three-dimensional space, not just ‘places’
Spatial layout hypothesis
Zeidman et al. (2012) showed that the PPA gets activated more when imagining space _ objects, as compared to space _ objects
space defining
space ambiguous
defining
ambiguous
strong sense of surrounding space (e.g. ‘a large oak bed’)
lack this characteristics
Binocular rivalry occurs when
each eye is presented with a different image
Tong et al. (1998) used binocular rivalry to demonstrate that changes in perception and changes in brain activity mirrored each other
When participants reported perceiving the house, the _ was active (and vice versa: the _ was active when perceiving the face)
PPA
FFA
refers to predicting what a person is perceiving or thinking about based upon their neural activity (typically accomplished using fMRI)
Neural mind reading
_ encoding: based on relationship between voxel activation and structural characteristics of a scene (e.g. shapes, lines, textures, etc.)
_ encoding: based on the relationship between voxel activation and the meaning or category of a scene
Structural
Semantic
attention is that it allows us to _ the processing of particular stimuli by _ out stimuli; important to avoid system _
prioritize
filtering
overload
_ _ refers to visually exploring the environment (i.e. looking from place to place)
This involves making many _, in which we dwell on something to extract information, which are linked by _ _ movements
This is necessary for low/high-acuity vision (on account of fovea vision) and we typically make about 3 saccades/second
Represents overt/covert attention
In contrast, overt/covert attention refers to attention that is decoupled from your gaze (e.g. watching something ‘out of the corner of your eye’)
Visual scanning
fixations
saccadic eye
high
overt
covert
_ _: areas of stimuli that attract attention due to their physical properties
Various properties relevant for contracting a salience map (e.g. colour, contrast, orientation, texture, movement, etc)
Visual salience
First few fixations heavy influenced by visual _ (after that scanning seems to be primarily driven by bottom-up/top-down mechanisms, e.g. goals, etc.)
salience
top-down
_ capture occurs when particularly salient properties of stimuli result in rapid and involuntary shifts of attention (e.g. something that stands out)
_ is heavily influenced by context
Attentional
Salience
Shinoda et al. (2001) measured observers’ fixations during computer simulated driving while searching for stop signs
participants more likely to detect stop signs when they were at _
this expectation based on prior knowledge directs their search behaviour (example of a _ regularity!)
intersections
semantic
Differences in eye movements related to task instructions/goals demonstrates a modulatory role for bottom-up/top-down processing
bottom-up
Determining where people look as they carry out tasks can be informative in various ways
This can provide insight into things like_ and _ making
More generally, demonstrates the link between _ and _
planning, decision
perception, action
Dichotic listening was an early paradigm used to study _ attention
One message is presented to the left ear and another to the right ear and participants are asked to _ one message while ignoring the other
Paradigm designed to test our control over _ attending to certain auditory stimuli
selective
shadow
selectively
The ability to focus on one auditory stimulus while filtering out others is often referred to as the
cocktail party effect
The results of the dichotic listening task indicated that participants were able/unable to report the content of the message in the unattended ear, supporting the idea they were largely able to filter out to the contents of one message over another (i.e. selectively attend)
This kind of result supported _ _ model
unable
Broadbent’s filter model
: process by which features (colour, form, etc.) are combined to create our perception of coherent objects
Binding
: features of objects are processed separately in different areas of the brain, yet somehow get integrated to form coherent representations which we perceive as singular objects
Binding problem
Treisman and Schmidt (1982):
Four coloured shapes and two numbers flashed onscreen very briefly, followed by a mask; report #s then colours/shape
_ _ which properties from different objects are erroneously bound together and perceived as being contained within the same object
Illusory conjunctions
Illusory conjunctions attributed to
task demands requiring divided attention which, along with the very brief display duration, prevented the complete processing of all stimuli
Illusionary conjunctions virtually eliminated in a condition where participants were only asked to report the _ / _ (i.e. ignore the numbers)
colours/shapes
proposes that binding occurs in two distinct stages:
Feature integration theory (FIT)
2 stages of FIT
_ stage: object features are extracted and processed (and proceeds automatically, no effort or attention required)
_ attention stage: extracted features are bound together to form coherent perception (attention plays a key role, and this is the point at which binding errors typically occur)
Preattentive
Focused
T/F: Combinations of colours/shapers that were consistent with ‘real-world’ knowledge produced fewer illusory conjunctions
represents bottom up/top down influence
t
top down
t/f: feature search requires binding
t/f: conjunctive search requires binding
f
t
_ search is typically not sensitive to (i.e. affected by) the number of distractors due to _ effect
feature
pop out
speed of a _ search typically is affected by the number of distractors
need to deploy focussed _
conjunction
attention
posner: _ accomplished with an arrow indicating which side of screen target was likely to appear
Target location was either consistent (valid trial: 80% of trials) or inconsistent (invalid trial: 20% of trials) with the cue
observers responded fastest on _ trials
Precueing
valid
refers to attention that has been bound to specific locations aka _ metaphor
Spatial attention
attentional spotlight
egly: cue signals where target likely to appear on rectangle
showed _ advantage
malcolm and shomstein demonstrated this w/ chairs indicated _ relevance
same-object advantage
real-world
carrasco et al: small dot flashed quickly on one side before gratings appeared; saw two different gratings very quickly, had to determine which one has higher contrast
what were the results?
this experiment suggests a shift of attention led to an effect on perception (and changed the _ _: how different the light and dark bars appeared to be
great contrast: dot had no effect
no contrast but were forced to pick a side: picked side with dot
perceived contrast
perceived contrast
how different the light and dark bars appear to be
O’Craven (1999) presented two competing images to participants; Rather than using binocular rivalry they had two superimposed images presented to both eyes, though one was moving and one was stationary
Attending to the face stimuli increased activity in the _
Attending to the house stimuli caused enhanced activity in the _
An area specialized for movement, _ / _, also showed activation when attending to whichever image was moving
FFA
PPA
MT/MST
Datta & DeYoe (2009) found that instructing participants to overtly/covertly direct attention to specific areas of space in their visual field corresponded with minimal/maximal activation across different areas of visual _
overtly
maximal
cortex
People can be unaware of clearly visible stimuli, even if looking direct at something, if they aren’t directing focussed attention towards it
Inattentional blindness:
participants were less likely to notice an auditory tone played during a difficult visual search, as compared to an easier one (Raveh & Lavie, 2015)
inattentional deafness
the common experience of failing to notice a change across two visual stimuli that are presented one after another
affected by top-down/bottom up mechanisms
Change blindness
top-down
Continuity errors in film are often missed by viewers, providing plenty of real-world examples of _ _
change blindness
Strayer and Johnston (2001) used a driving simulator to manipulate smartphone use
Idea of intermittent distractions leading to ‘_ _ attention’
Ward et al. (2017) manipulated location of smart phone across three groups during a battery of cognitive tests
Results interpreted as ‘smartphone induced _ _
continuous partial
brain drain’
Experiment by Li et al. (2002): Participants performed the central task along with one of two peripheral tasks
Central task: determine whether letters flashed in the centre of the screen are the same or different peripheral: discuss if you saw either an animal or the order of colours in coloured disc
performance results of animals vs coloured disk
good performance with secondary pic but not secondary coloured disc
poor performance of secondary coloured disc indicates _ error predicted by _ when focused attention is present/lacking
binding
FIT
lacking
Load theory begins with the premise that people have a particular _ capacity
perceptual
perceptual capacity
‘upper-limit’ on the amount of perceptual information their system is able to process at any one time
what’s the following and how much residual resources are left behind
low load
high load tasks
Low-load tasks use relatively little of our total perceptual capacity, leaving some/lots of residual ‘resources’ to process other things
High-load tasks use most/all of our total perceptual capacity, leaving no/few residual ‘resources’ to process other things
_ - _ stimuli are stimuli that do not provide information relevant for whatever is considered the primary task
Load theory predicts that task-irrelevant stimuli (e.g. distractors) will be processed to a greater extent under conditions of low/high load and processed less during low/high load
Task-irrelevant
low
high
Kapadia’s (2000) research shows that the response to stimulation within the receptive field can actually be affected by what’s happening outside of the receptive field, an example of
contextual modulation
Womelsdorf et al. (2006) show a shift in the location of a receptive field related to attention -> shows the _ of the perceptual system
flexibility
Ecological validity refers to the
degree to which the conditions, stimuli, and procedure used in experiments match those present in the natural world
Gibson emphasized:
Studying the acting _
How _ can create perceptual information that helps guide behaviour in the environment
- _: information that we generate ourselves by acting in the environment
_ information: source of information that are present in the environment across different contexts
The way our senses work together (i.e. _ integration)
observer
movement
Self-produced information
Invariant
multimodal
_ _ refers to the pattern of apparent motion perceived by an observer as they move through space (i.e. relative motion)
Involves creating _ of objects and the scene, relative to the observer
Optic flow
movement
_ of flow: difference in flow rates as a function of distance from the observer
Flow is faster nearer/farther to the moving observer
Flow is slower nearer/farther away from the moving observer
Gibson argued the gradient of flow can be used to estimate _
Gradient
nearer
farther
speed
_ _ _: absence of flow at destination point’ in distance
Indicates where one is _ _
Focus of Expansion (FOE)
directly headed
_ information: information that remains constant regardless of what the observer is doing or how they are moving in the environment
eg. _ flow –> _ is always at point toward which observer is moving
Invariant
optic
FOE
movement info provides _ loop and reciprocal relationship
feedback
Warren (1995): In the absence of other stimuli, participants can use the information produced by _ _ related to a field of dots to judge where they are heading (relative to the vertical line) within ~0.5-1 degree
optic flow
patients with _ disease benefit from manipulations that draw attention to _ information to help guide _
Parkinson’s disease
visually-based information
movement
_ _is important in lots of contexts, and the _ approach to perception placed a greater importance on the way our senses work together to achieve goals
Multimodal integration
Gibsonian
Bardy and Laurent (1998) found that expert (but less so novice) gymnasts performed worse with their eyes closed
experts learned to use _ to correct trajectory
vision
Swinging room experiment by Lee and Aronson (13-16 mo)
optic flow pattern indicates infant is falling forward, infant compensates and moves _; pattern indicates infant is falling back, infant moves _
results demonstrate _ response that’s normally _
t/f: adults showed same response
back
forward
compensatory, adaptive
t
Gibson believed _ of objects are made up of information that indicates what an object is used for, indicating a ‘potential for action’, or “…what the environment offers the animal, what it provides or furnishes.” aka another _ of info
affordances
source
humphreys and riddoch: pt w/ temporal damage, impaired ability to name objects
cued object by _ or _
cueing provided better/worse performance
name, fx
better
Proverbio et al. (2011) used EEG to record neural responses
found larger neural response for _ vs _ - _
interpreted as _ _
tools
non-tools
‘action affordance
‘action affordance
action-based information (the affordance, or what it does, and the action associated with it) is automatically activated during early stages of processing
_ _ strategy involves keeping ones body pointed toward a target
Walkers simply correct their _ when target drifts to left or right in their visual field
visual direction
trajectory
blind walking shows people can still navigate surroundings by using
indicates _ _ can happen w/o input
non visual sources of info
spatial updating
spatial updating
keeping track of one’s postiion as they move around environment
land and lee car stimulation: thought drivers would focus on FOE since its their final destination but drivers actually focused _ to the car
closer
amrefers to navigating to a destination that requires making a series of turns
are objects on the route that serve as cues to indicate where to turn
Wayfinding
Landmarks
hamid eye tracking
training phase: navigate virtual maze with landmarks
testing phase: try and reach specific spots; wanted to compare fixation on decision point landmarks vs non-decision point landmarks
Decision-point landmarks fixated more/less than non-decision-point landmarks
more
hamid: removing least fixated landmarks had major/minor impact on performance
removing most fixated landmarks had major/minor impact on performance
minor
major
Janzen and van Turennount:
objects that were remembered, those at decision-points were associated with greater _ gyrus activation than those at non-decision points;
t/f: same for those that weren’t remembered
suggests explicit/implicit processing of landmark related objects
indicates
parahippocampal
t
implicit
__ agnosia refers to an inability to recognize landmarks
Associated with damage to the __ gyrus
Topographical
parahippocampal
tolman, rat, cheese maze
shows that rats could make _ maps
t/f: this was reinforcement
cognitive
f
_ _: neurons that fire when in particular locations (their ‘place field’)
Place cells
