PERCEPTION Flashcards
Perception:
interpretation of the sensory information to figure out what is out there and where it is.
Perception is the result of the reciprocal interaction between …………………… processes.
bottom-up and top-down
top-down:
expectation-driven processing
internal knowledge, beliefs, goals
bottom-up:
stimulus-driven processing (information from the external environment)
Same input can be interpreted in different ways
True or False?
True
can you see both interpretations at once?
No, but can spontaneously alternate between the two interpretations.
What does the bistable perception demonstrate?
The visual system is highly dynamic and continuously recalculates the best possible solution to the ambiguity in sensory info.
Gestalt is German for???
“form” or “shape”
What did Gestalt psychologists begin to uncover?
some of the grouping principles that guide the visual system and produce our perception of what goes with what.
The Gestalt Laws:
provide a description of perceptual principles that aid in our perception of whole forms.
Visual stimuli are perceived in a way that most simply…?
organises the different elements into a coherent form.
Name the 6 Gestalt Laws
proximity, similarity, symmetry, continuity, closure, figure-ground
Describe the Gestalt Law Proximity
(no grouping)
elements that are close are perceived as forming a group
Describe the Gestalt Law Similarity
elements that are similar are perceived as forming a group
colour
size
orientation
Describe the Gestalt Law Symmetry
elements that form a figure that is symmetric around its centre are perceived as a group
Describe the Gestalt Law Continuity
continuation groups the dots into two lines that are intersecting
Describe the Gestalt Law Closure
edges that are separated by gaps are perceived as belonging to complete objects
Describe the Gestalt Law Figure-groud
some elements are prominent (figure) while other elements recede into the background (ground)
Describe image-based models
Template matching models: Match the whole image to the stored representation
Describe Part-based models
Recognition-by-components model: Specify the parts and spatial relations among the parts of 3D objects
Exemplar variation:
There many different instances of each object category and yet these can be recognized. How many templates can possibly be stored?
What is Assumption in the recognition by components model?
Any 3D object can be described by their parts and the relations among these parts.
Recognition by components model:
Recognition by components (RBC) model provides a building model that accounts for both parts and their spatial connections
How many shapes does the recognition by components model define?
The model defines 36 shapes (called geons) that can build up any object
What does the recognition by components model detect?
The models detects the geons and spatial relations and attempts match them to a known object
Depth perception:
Ability to perceive the external world in 3D and distances to external entities.
Projections on the retina are ambiguous and they could be caused by an infinite number of external entities.
What are the 3 depth cues?
Monocular cues
-Information from one eye
Binocular cues
-Information from both eyes
Motion based cues
Components of Monocular depth cues
Interposition - nearby objects occlude faraway objects
Linear perspective - Parallel lines converge in the distance
Relative size - for two objects that are typically the same size, the larger object is nearby and the smaller object is faraway.
Texture gradient - Fine detail (“grain”) of nearby objects can be seen while fine detail of faraway objects cannot.
Interposition:
nearby objects occlude faraway objects
Components of binocular depth cues
Binocular disparity - the eyes send more disparate signals to the brain when objects are nearby vs faraway. Difference in left and right retinal images provide information about depth. The larger the disparity the closer the object
Convergence - the eyes turn more inward when objects are nearby vs faraway. Eye muscles provide information about the depth.
Motion parallax:
when moving, distant objects appear to move slower.
