Week 2 Perception Flashcards
perception
experiences resulting from stimulation of the senses and interpreting it
central to our ability to organize actions as we interact with our environment
central role in cognition
The fovea has extra concentration of photo receptors resulting in __
high acuity information, extra detail
where does transduction in the eye take place
the retina
blind spot is where the optic nerve
leaves the eye
true or false, visual info is presented upside down on the retina
true
what is transduction
changing a physical stimulus into energy
where in the retina does transduction take place
rods and cones (fovea only has these) that are distributed across the eye, although no absolute boundary in their numbers
what did studying blindsight reveal
there are multiple paths for visual information (ie. detecting motion)
so may not have conscious interpretation, but other pathways can influence it
what is blindsight
patients with damage to the occipital lobe who are blind, eyes and optic nerve are still intact
what is the inverse projection problem
recovering a 3D perception from a 2D image on the retina, as many objects can create the same image so we have to overcome this
perceptual system starts with the image on the retina
proximal and distal stimulus
Reflected on retina to help us interpret the world are the proximal stimulus
Distal is what the stimulus is out in the world
viewpoint invariance
the ability to recognize an object from different viewpoints
bottom up processing (data driven processes)
Sequences of events from eye to brain
○ Starts at beginning of system, where the environmental energy stimulates the receptors, then generates signals that are transmitted to the brain
- Information stimulating receptors
Perception involves information in addition to the foundation of bottom up processing
- Factors: knowledge of the environment, expectations
scenes are more complex to perceive than object because
we need to use reasoning to figure things out
how do we understand that a covered or blurred object is still a whole object
from interacting with our environment and our past experiences
two types of info used by the human perceptual system
Environmental energy stimulating the receptors
Knowledge and expectations that the observer brings to the situation
Top down processing (conceptually driven processes)
Process originates at the brain (top) of perceptual system
Involves knowledge/expectations
Information based on knowledge
how does the brain solve the problem of visual perception
use information from both eyes (binocular cues) and properties from the proximal stimulus (monocular cues) to make inferences about relative depth of the distal stimulus
what are the two binocular cues
convergence: eyes converge and lens accommodates when objects are close (how close)
binocular disparity: gages distance
how do transitional properties help a child perceive words
the likelihood that one sound will follow another can help make transitions between words - lead to speech segmentation
Judgement of what is most likely is a process called ___
unconscious inference
§ Our perceptions are the result of unconscious assumptions/inferences about the environment
□ Likely based on past experiences
likelihood principle
We perceive the object that is most likely to have caused the pattern of stimuli we have received (Helmholtz)
relative size (monocular cue)
bigger things tend to be closer - can help us make assumptions on how close something is
perspective (monocular cue)
lines converge at a distance
assumption of distance leads to assumption of size
train tracks
interposition (monocular cue)
closer objects obscure/cover up distant ones
texture gradient (monocular cue)
less detailed the texture, the farther away
blurring can give the impression of depth
motion parallax (monocular cue)
objects that are closer move past more quickly than object farther away
interpret distance
aerial perspective
farther away something is, the more there is a blueish haze
shading (monocular cue)
info about depth and movement
light is assumed to come from
above
Gestalt’s law of similarity
group things that look alike
what is the idea behind Gestalt psychology
looks at how we segregate and group visual information, a tool
thought to be innate
the whole is more than the sum of its parts
Gestalt’s law of proximity
group things that are closer together
Gestalt’s law of good continuation
when connected, result in straight or smoothly curving lines are seen as belonging together, and the lines tend to be seen in such a way as to follow the smoothest path
Gestalt’s law of closure
when there is a gap in features we assume there is an edge, imply contours that arent there, or fill in lines/edges
Gestalt’s law of common fate
move together, grouped together
Gestalt’s law of Pragnanz
stimulus pattern seen in the way so that the resulting structure is as simple as possible
Physical regularities in the environment that we are adapted to
Regularly occurring physical properties of the environment
§ More horizontal/vertical orientations in the environment than angled ones
§ We can therefore perceive horizontals/verticals more easily than other orientations
The oblique effects
Light from above assumption
□ We usually assume light comes from above (bumps/mounds or indents in the sand)
semantic regularities in the environment that we are adapted to
Meaning of a scene- Often related to what is happening in the scene
□ Food preparation (cooking, being in a kitchen)
The characteristics associated with the functions carried out in different types of scenes
Scene schema
Bayesian inference
can estimate the probability of an outcome by determining the prior/prior probability (initial belief of the probability or knowledge you are bringing to the situation), and the likelihood of the outcome
prior strengthened when it aligns. - becomes prior for next experience
brain ablation
the study of the effect of removing parts of the brain in animals
main difference between these approaches: Helmholtz’s unconscious inference, Gestalt laws of organization, regularities in the environment, Bayesian inference
Helm, Bayes, and Reg: use data from environment/experiences and top down processing
Ges: processing is built in, bottom up
What are the two types of processing in the brain related to perception and action? A:
Perceiving objects
Locating and taking action toward objects
What are the two tasks used in brain ablation studies with monkeys?
- Object discrimination problem
- Landmark discrimination problem
“What pathway” (Ventral pathway) connect and do?
Connects: Occipital lobe → Temporal lobe
Responsible for: Determining an object’s identity (perceiving objects)
What does the “Where pathway” (Dorsal pathway) connect and do?
Connects: Occipital lobe → Parietal lobe
Responsible for: Determining an object’s location (locating objects)
What are mirror neurons and where are they located?
Neurons located in the premotor cortex
Respond to performing an action and observing someone else perform the same action
signal intention
How do mirror neurons signal intention?
A:
By responding to the sequence of actions most likely to follow in a given context
They reflect the expected motor sequence based on the context
The bottom up theories and their limitations
template theory: whatever information comes in, we have a matching idea of what that object is (they match we identify) - limitation is rigid
feature theory: hierarchal understanding: stimuli as a combination of elemental features, search for memories of those features (break down to reconstruct) - limitation, what is a feature? no room for relative spatial positions
prototype theory: the ideal for a category, object compared to ideal, look at the whole, allows for spatial positioning/variation of real world
- studied by Posner and Keele
- limitation is they are vague
how do we recognize objects are discussed by
object centered theories (feature position relative to other complex 3D features)
and viewer-centered theories (store representations, transform stimuli to match them)
Biedermans Recognition by Components
geons and objects, if we recognize the components we will recognize the object, intersections are important
Tarrs multiple view theory
we store viewpoints in our head, evidecence comes from recognition of novel objects from different view points
what theory of object perception is important for decision making
Bayesian
