Exam 2 Flashcards
Attention
Process of focusing on some objects while ignoring others
Covert attention
Attention without looking directly at the object
Overt attention
Attention while looking directly at the object
Posner’s Precueing experiment
Showed that attention can enhance processing of a stimulus
Precueing
Presenting a cue indicating where a test stimulus will appear enhances the processing of a target stimulus
Treisman’s feature integration theory
an object is broken down into separate features and then the features are recombined to create our conscious perception of the object.
Treisman’s preattentive stage
Objects are analyzed into separate features
features exist independently, before conscious awareness, automatic and effortless
Treisman’s focused attention stage
Features are combined and we perceive the object
conscious awareness, influenced by attention
Divided attention task
Participants must pick out several features from an image after viewing for a limited time
results in illusory conjunctions
Illusory conjunctions
incorrect combination of features from different objects
Balint’s syndrome
parietal lobe damage that causes the inability to focus attention on individual objects
How does top-down processing prevent illusory conjunctions
we use our knowledge of what features common objects have to avoid mixing up features between objects
Visual scanning
moving the eyes to focus attention on different locations on objects or in scenes
Visual fixations
When the eyes stop moving to focus on something
Visual saccades
Eye movements between fixations
Corollary discharge theory
Explains why we don’t perceive the world as moving when we move our eyes
Takes eye movements into account, considers signals from the retina and eye muscles
Motor signal (MS)
(Corollary discharge theory)
command the brain sends to the eyes telling the eyes to moves
Corollary discharge signal (CDS)
Copy of the motor signal that goes to a different part of the brain to alert that the eyes are moving
Image displacement signal (IDS)
signal sent when image on the retina has changed
Comparator
Receives IDS and CDS
Hypothetical model that has not been localized in the brain
What happens when CDS and IDS occur at the same time
the brain knows the eyes are moving, not the scene
what happens when either CDS or IDS is received by the comparator?
Movement is perceived
Salience
physical characteristic of a stimulus that makes it stand out
ex. color, motion
Attentional capture
involuntary shift in attention caused by a salient stimulus
Attention is influenced by _______
Scene schemas, task demands, and interests and goals
inattentional blindness
failure to notice something that is completely visible because the person was actively attending elsewhere
Change blindness
Failure to notice a change between two visual stimuli presented one after another, with a short delay between
When is optic flow the fastest
for objects that are closest to you
Landmarks
Objects on a route that can serve as cues to indicate where to turn
Brain activation is greater at? (Decision point vs non decision point landmarks)
Decision point landmarks
Topographical agnosia
the inability to recognize landmarks
Cognitive map
a mental map of the spatial layout of an area of the environment
Place cells
fire when animal is in a certain place
Grid cells
fire when animal is in one of a set of places arranged in a hexagonal grid
helps determine direction and distance
Where are grid cells
entorhinal cortex
Head direction cells
fire when animals head is facing a certain direction
border cells
fire when animal gets close to the borders of its environment
Affordances
information that indicates how an object can be used
Acting on objects involves the coordination of the…
dorsal and ventral pathways
Parietal reach region (PRR)
Contains neurons that control grasping and reaching
different neurons respond to different types of grips
visuomotor grip cells
respond to both perception and action related to gripping something
proprioception
the ability to sense the position and movement of the body and limbs
Proprioceptors
Receptors that detect the position or movement of a part of the body
Muscle spindles
respond to stretch of muscles
Golgi tendon organs
respond to tension
Size weight illusion
occurs when a person incorrectly predicts that a larger weight will feel heavier, resulting in the perception that it’s lighter
the one they predicted would be heavier they use more force to lift, making it appear lighter when they compare it to the smaller object of the same weight
Motion perception
gives us information about objects
helps us understand events in our environment
Event
a segment of time at a particular location that is perceived to have a beginning and an end
Event boundary
point in time when one event ends and another begins; associated with changes in nature of motion
Spatial neglect
neurological condition in which patients with damage to one hemisphere of the brain do not attend to the opposite side of the visual field
Failure of attention, not vision
Ecological approach to perception
Focuses on specifying information in the environment that is used for perception, emphasizing the study of moving observers to determine how their movement results in perceptual information that both creates perception and guides further movement
Proposed by JJ Gibson
Optic flow
The flow of stimuli in the environment that occurs when an observer moves relative to the environment
speed and directional information
Invariant information
information that remains constant regardless of what the observer is doing or how the observer is moving
Self-produced information
Perceptual information produced by the actions of the observer
ex. driving, dancing
Isolated optic flow information can help determine…
direction
Optic flow neurons
neurons in the medial superior temporal area of monkeys to respond to flow patterns
Lee & Aronson (1974) swinging room
- Emphasis on moving observer
- Identification of invariant and self-produced information in the environment that observers use for perception and movement
- Consideration of cooperation between senses
Visual direction strategy
Keep body oriented toward target
Spatial updating
Combines knowledge of movement and memory of target location
Wayfinding
process of navigation through the environment that involves
-perceiving objects in environment
- remembering objects and their relation to the overall scene
- Knowing when to turn and in what direction
Perceived motion can be…
real or illusory
real object perception and apparent motion perception seem to involve.. (similar or different brain mechanism)?
Similar brain mechanisms
Induced motion
motion of one object (usually larger) causes a nearby stationary object (usually smaller) to appear to move
ex. moon racing through the clouds
Motion aftereffects
occurs when a person views a moving stimulus and then sees illusory movement in the opposite direction when viewing a stationary stimulus immediately after
Optic array
pattern of light created by the environment
Local disturbance in optic array
One object moves relative to environment
Global optic flow
All elements move
Reichardt detector
a neural circuit that results in neurons firing to movement in one direction
Middle temporal (MT) area
involved in detecting speed and direction of motion
Aperture problem
viewing only a small portion of a larger stimulus can result in misleading information about the direction the stimulus is moving
biological motion
motion produced by biological organisms
Superior temporal sulcus (STS)
Perception of motion related to animals and people (biological motion)
Medial superior temporal (MST) area
processing optic flow; locating moving objects; reaching for moving objects
Striate cortex (v1)
direction of motion across small receptive fields
Functions of color vision
-serves as a signal
-aids with perceptual organization
-helps with object identification
perceived color is most closely associated with the ___ of the light
Wavelength
The color we perceive an object to be is generally determined by what wavelength of light it ___.
Reflects
Chromatic colors (hues)
some wavelengths reflected more than others
achromatic colors
all wavelengths reflected equally
The color of a transparent object is determined by what wavelength it____.
Transmits
Mixing pigments results in
Subtractive color mixing
both paints still absorb the same wavelengths they absorbed when alone, so the only wavelengths reflected are those reflected by both paints in common
Mixing lights results in
additive color mixing
all of the light that is reflected from the surface by each light when alone is also reflected when the lights are superimposed
ex). blue+yellow = white
Spectral colors
colors in the visible light spectrum
nonspectral colors
colors not visible in the light spectrum
Hue
experience of chromatic color
saturation
amount of whiteness
value
light- dark
trichromatic theory of color vision
color vision depends on the ratio of activity in three receptor mechanisms, each with a different spectral sensitivity.
Young-Helmholtz color matching experiments
possible to match any wavelength by adjusting three wavelengths
three cone pigments identified by the trichromatic theory of color vision
Short-wavelength pigment (S)
Medium-wavelength pigment (M)
Long-wavelength pigment (L)
how do the three cone types determine what color we perceive?
The ratio of responses by the three cone types determines what color we perceive
Why are three receptor mechanisms necessary?
Having multiple pigments makes it possible to distinguish between wavelengths independent of light using ratio information
Color deficiency
partial loss of color perception
Monochromatism
occurs when there are no functioning cones or just one type of cone pigment
see in shades of lightness
Dichromatism
occurs when someone is missing one type of cone pigment
experience lesser range of color than trichromats
protanopia
the long-wavelength pigment is missing
deuteranopia
medium wavelength pigment is missing
tritanopia
short-wavelength pigment is missing
anomalous trichromats
have all three cone types but the spectral sensitivities are more overlapping
Opponent-process theory
our perception of color is determined by the activity of three opponent mechanisms
what are the three opponent mechanisms of the opponent process theory?
Blue-yellow
red-green
black-white
responses to the two colors in each mechanism oppose each other with one being excitatory and one being inhibitory
behavioral evidence for the opponent-process theory
color deficiency
phenomenological evidence (primary colors)
complementary afterimages
complementary afterimages
after staring at an image the after image has the opponent colors
opponent neurons
respond with an excitatory response to light from one part of the spectrum and with an inhibitory response to light from another part of the spectrum
Bipolar cells send signals to ____.
opponent neurons in the brain
V4
brain area specialized for color vision
cerebral achromatopsia
color blindness due to damage of the brain
color perception also involves other areas, it has ____.
distributed representation
color constancy
we perceive the colors of objects as being relatively constant even under changing illuminations
chromatic adaptation
exposure to light in a specific part of the spectrum causes a decrease in sensitivity to light from that part
color constancy works better with ____.
more context
memory color
the effect on perception of prior knowledge of the typical color of objects
lightness constancy
constancy of our perception of an object’s lightness under different intensities of illumination
percent of light reflected remains constant.
illumination edge
shadow
how do we determine if there is an illumination edge
meaningful shape, penumbra (unclear border)
how is color a construction of the nervous system
wavelengths are not colored, the brain colors them
Cue approach to depth perception
focuses on identifying info in the retina that is correlated with depth
Oculomotor cues
cues based on our ability to sense the position of our eyes and the tension in our eye muscles
Convergence
inward movement of eyes
Accommodation
changes in lens shape
Monocular depth cues
cues that can work with only one eye
-accommodation
-pictorial cues
-motion produced cues
Pictorial cues
sources of depth info that can be depicted in a picture
Occlusion, relative height, relative size, perspective convergence,
familiar size, atmospheric perspective, texture gradient, shadows
Pictorial cues- occlusion
when one object hides or partially hides another object from view, that object is perceived as closer and the object that is being occluded is perceived as further away
Pictorial cues- relative height
Objects closer to the horizon appear further away
Pictorial cues- relative size
when two objects are of equal size, the one that is farther away will take up less of the field of view
Pictorial cues- Perspective convergence
perception that parallel lines in the distance converge as distance increases
Pictorial cues- familiar size
judgment of distance is based on knowledge of the sizes of the objects
Pictorial cues- atmospheric perspective
objects that are farther away look more blurred and bluer than objects that are closer because we must look through more air particles to see them
Pictorial cues- texture gradient
the elements in a texture gradient (visual pattern) appear smaller as distance from the observer increases
Pictorial cues- shadows
decreases in light caused by the blockage of light can provide information regarding the location of objects
Motion parrallax
the phenomenon that as we move, nearby objects appear to move past us more quickly than distant objects
Accretion
when a farther object is uncovered by a nearer object due to a sideways motion of an observer relative to the objects
Deletion
when a farther object is covered by a nearer object due to a sideways motion of an observer relative to the objects
accommodation and convergence are only used when
an object is nearby
atmospheric perspective is only used when
an object is very far away
Binocular depth cues
require two eyes
Stereoscopic depth perception (stereopsis)
two-eyed depth perception involving mechanisms that take into account differences between each eye
Strabismus
misalignment of the eyes
no binocular information because vision is dominated by one eye
How do 3D glasses work?
each eye gets two different images to create a 3D image
Binocular disparity
difference in the images on the left and right retinas
Corresponding retinal points
points on the retina that overlap if the eyes are superimposed on each other
horopter
imaginary surface that passes through the point of fixation
noncorresponding points
the images of objects that are not on the horopter
Absolute disparity
degree to which an object deviates from falling on corresponding points
indicates the distance from the horopter and from you
angle of disparity
amount of absolute disparity
Binocular depth cells
respond to absolute disparity
found in v1, dorsal pathway
Dorsal pathway
How/ action pathway
Our size perception is affected by ____.
depth perception
Holway & Boring experiment
investigated how size perception and depth perception interact
first phase- many depth cues available
second phase- eliminated depth cues
without depth cues, size perception is based on visual angle and is innaccurate
Visual angle
angle of an object relative to the observer’s eye
depends on size and distance
determines how much space the image takes up on the retina
Size constancy
Our perception of an object’s size is relatively constant even when we view the object from different distances
Size constancy is decreased under conditions of ____.
poor depth information
Size-distance scaling
mechanism that maintains size constancy by taking into account perceived distance
Ponzo illusion
two objects of equal size positioned between converging lines appear to be different in size
Ames room illusion
Two people of equal size appear different in size because of a distorted room
