Problem 5 Flashcards
Inverse projection problem
The task of determining the object responsible for a particular image on the retina
–> involves starting within the retinal image, then extending rays out from the eye
Viewpoint invariance
The ability to recognize an object seen from different viewpoints
–> enables people to tell whether faces seen from different angles are the same person
Perceptual organization
The process by which elements in the environment become perceptually grouped together to create our perception of objects
–> consists of 2 elements
a) grouping
b) segregation
Grouping
Process by which visual events are put together into units or objects
ex. : Dalmatien dog
- -> dark spots where put together to perceive it
Segregation
Process of separating one area/ object from another
ex.: the boarders from two buildings indicate where one building ends and the other begins
What is the main question of “Gestalt psychologists” ?
How are configurations formed from smaller elements ?
Gestalt = configuration
Structuralism
Distinguish between
a) sensations
b) perceptions
- -> believe that sensations combine to create perceptions
- -> this combination is aided by the observers past experience
Apparent movement
Although a movement is perceived, nothing is actually moving
- -> this can’t be explained by sensation
- -> the perceptual system creates a perception of movement where there actually is none
ex.: moving advertisements at the train station
=> Gestalt psychologists counter argument to structuralism
Principle of Good Continuation
Gestalts organizing principle
Objects that are partially covered by other objects are seen as continuing behind the covering object
Principle of Prägnanz
Gestalts organizing principle
Every stimulus is seen in such a way that the resulting structure is as simple as possible
ex. : Olympic symbol
- -> we see 5 circles, not a large number of more complicated shapes
( Central Principle )
Principle of Similarity
Gestalts organizing principle
Similar things appear to be grouped together
–> grouping can also occur due to similar
a) shape
b) size
c) orientation
Principle of proximity
Gestalts organizing principle
Things that are near each other appear to be grouped together
Principle of common fate
Gestalts organizing principle
Things that are moving in the same direction appear to be grouped together
ex.: birds moving in the same direction appear as a unit
Principle of common region
Gestalts organizing principle
Elements that are within the same region of space appear to be grouped together
–> common region overpowers proximity
Principle of uniform connectedness
Gestalts organizing principle
A connected region of the same visual properties is perceived as a single unit
–> connectedness overpowers proximity
Principle of synchrony
Gestalts organizing principle
Objects that move at the same time and in sync, even when not close, are grouped together
Principle of familiarization
Gestalts organizing principle
Things that form patterns that are familiar or meaningful are likely to be grouped together
–> categorization
What are the main beliefs of the Gestalt psychologists ?
” the whole is different than the sum of its parts ! “
- Sensation is not needed to create perception
- Past experience doesn’t play a role in perception as good continuation overrides it
Figure - ground segregation
We usually see a separate object as a FIGURE that stands out from its background (GROUND)
Reversible figure - ground
Occurs when the figure can also be perceived as the ground and vice versa
–> areas lower in the field of view are more likely to be perceived as a figure
Surroundedness
If a region is in the middle of the picture / surrounded entirely by different regions, this region is the figure
Extremal edges
Answers the question if a particular region is in front of another, by different shadings of the edges
–> overrides surroundedness
Symmetry
Symmetrical regions are more likely to be seen as a figure
Parallelism
Parallel contours are more likely to belong to the same figure
Relative motion
Moving objects are more lily to be seen as figures
Scene
Refers to a view of a real world environment that contains
a) background elements
b) multiple objects that are organized in a meaningful way
- -> objects are acted upon
- -> scenes are acted within
Gist of a scene
Refers to the general discription of a type of scene after viewing it for a fraction of a second
Global image features
Enable us to perceive the gist of a scene
–> asses the degree of
a) naturalness
b) openness
c) roughness
d) expansion
–> contain information about a scenes structure + spatial layout
Physical regularities
Regularly occurring physical properties of the environment
- there are more horizontal + vertical orientations on the environment
- nearby objects usually have different colors
(light-from-above assumption)
Semantic regularities
Characteristics associated with the functions carried out in different types of scenes
–> one usually knows how to visualize a particular scene
Theory of unconscious inference
Some of our perceptions are the result of unconscious assumptions we make about the environment
–> explains our ability to create perceptions from a stimulus information that can be seen in more than one way
Likelihood principle
We perceive the object that is most likely to have caused the pattern of stimuli we have perceived
–> related to the theory of unconscious inference
Binocular fusion
Two slightly different images from the eyes are similar enough to be combined into a single perception by the brain
Binocular rivalry
Condition, where the observer either perceives the left eyes image or the right ones, but not both at the same time
- -> occurs because the images received by both eyes are totally different
- -> the activity in the brain changes depending on what the person experience
Visual word form area
Small region of the visual system that systematically activates whenever we read
–> falls within the fovea ( to be able to discriminate very small shapes )
–> is lateralized to the same hemisphere as spoken language
–> falls in the left hemisphere, then shifts to the right
Pure Alexia
Inability to recognize even a single word / digits / objects / faces
–> condition that results from a disconnected or impaired VWFA
Which abilities does literacy refine ?
- Capacity to recognize any picture
- V1 area
- Cortical responses to faces are displaced from left to right hemisphere
- Mirror invariance
- Phonological awareness
- the fast + bidirectional connection between letters and sounds
ex. : removing the “n” form “bind” –> “bid”
Cortical competition
As cortical territories dedicated to older functions are invaded by novel cultural objects, their prior organization should slightly shift away from the original function
Mirror invariance
Objects maintain their identity across a left - right inversion
ex:. p is not = q –> for literate people
p = q –> for illiterate people
Phonological awareness
Skill that allows us to recognize and work with sounds of spoken language
Border ownership
The border separating the figure from the ground appears to belong to the figure
To what do the different visual areas of the temporal respond best ?
(V1, V2, V3)
V1 - Low level vision
–> responds best to lines + edges
V2 - Middle level vision
–> responds best to border ownership + illusory contours
V3 - High level vision
–> responds best to complex attributes
ex.: warmer + darker colors
Naïve template theory
The visual system recognizes objects by matching the neural representation of the image, with a stored representation of the same ‘shape’ in the brain
Recognition by components model
Biederman
Objects are recognized by separating them into their main component parts
