4 Flashcards
How do elements in a person’s visual field create a perception?
the elements become grouped and segregated to create a perception
What is grouping?
elements are put together into coherent objects
What is segregating?
the process of separating one object from another
What did structuralism psychologists do?
distinguished between sensations and perception
What is the principle of structuralism?
sensations combine to create complex perceptions
1+1=2
What is the limitation of structuralism?
the perception is not always equal to a combination of the sensations
What is a violation of structuralism?
apparent movement
What is apparent movement
the illusion of movement caused by two rapidly alternating light flashes
we dont see the darness between the light because our perceptual systems fills it in
so we see the perception of light flashes moving through the space when there actually isnt any movement
What are illusory contours?
edges create a triangle when there are no physical edges present
clearer edges if we add more pac man figures and lines
sensations cant explain illusory contours because there arent any sensations along the contours
What is gestalt psychology?
the whole is different than the sum of its part
“whole” has priority and that the “parts” are defined by the structure of the whole, rather than the other way around
What 2 topics cant be explained by sensations alone?
apparent movement and illusory contours
What are the principles of gestalt psychology?
“Some Great Penguins Swim Calmly Under Sunlight.”
Some - Similarity
Great - Good Continuation
Penguins - Proximity
Swim - Simplicity
Calmly - Common Fate
Under - United Connectedness
Sunlight - Common Region
What is the principle of good continuation?
connected points that result in a smoothly curving line are seen as belonging together
lines tend to be seen in a way as to follow the smoothest path
What is the principle of simlicity?
aka principle of pragnanz (good figure)
every stimulus is seen as simlply as possible
What is the principle of similarity
similar thigns are more likely to be grouped together
grouping can occur because of similarity in shape, size, or orientation
What is principle of proximity?
near things are likely to be grouped together
What is the principle of common fate
things that are moving in the same direction are likely to be grouped together
What is the principle of common region?
things in the same region tend to be grouped together
common region overpowers proximity
What is the principle of uniform connectedness?
connected regions of visual properties are perceived as single unit
connectedness overpowers proximity
What is figure-ground segregation?
figure: the object
Ground: the background
What is Rubin’s reversible figure?
Can be percieved as 2 images depending on how one segregate figure and ground
What are gestalt figural cues?
cues that determine how an image is segregated into figure and ground
What are 2 gestalt figural cues?
- areas lower in the field of view are more likely to be perceived as figure
- figures are more likely to be perceived on the convex side of borders (borders that bulge outwards)
What do gestalt psychologists say about perceptual principles and past experience?
perceptual principles can override one’s past experiences in determining perception
see letters on the left
but principle of good continuation overrides the effect of past experience with Ws or Ms
but there is also opposing evidence
* participants were more likely to say that the meaningful part was the figure (the women)
* but if the image was turned upside down, participants were less likely to see that area as being the figure
* shows that figure ground formation can be affected by the meaningfulness of stimulus
What is a scene?
a view of a real world environment that contains background elements and some meaningful objects
One way to distinguish object vs scenes - objects are compact and are acted upon, scenes are extended in space and are acted within
street is scene, mailbox is object
What is a gist of a scene?
the general description of the type of scene
scenes are often large and complex
but we can quickly identify important properties of most scenes after viewing them
and it takes less than <250ms
What is Li fei fei’s study on perceiving the gist of a scene?
- participants were shown scenes for 27-500ms and write what they saw
- 67ms they could identify some large objects
- 500ms they were able to identify smaller objects and details
- overall gist of the scene is perceived first, followed by smaller objects within the scene
What are physical regularities in the environment?
- regularly occuring physical properties of the environment
- human made and natrual scenes contain more horizontal and vertical orientations like buildings, trees and plants
- people perceive horizontal and vertical orientations more easily than other orientations, more sensitive
What are semantic regularities?
- characteristics associate with activities that are common in different types of scenes
- refers to meaning of a scene
- e.g. cooking usually occurs in the kitchen
What did Palmer’s experiment show about semantic regularities?
- presented a context scene
- then briefly flashed on eof the target pictures on the right
- when asked observers to identify the object in the target picture, they correctly identified an object like a loaf of bread which is appropriate to the context scene of a kitchen 80% of the time
- but correctly identified the mailbox or the drum (neither fit in scene) only 40% fo the time
- using knowledge about kitchens help them perceive the loaf of bread
Where do the different object/scene perception take place in the brain?
- lateral occipital complex (LOC) - all kinds of objects
- Fusiform face area (FFA) - faces
- Extrastriate body area (EBA) - bodies
- Parahippocampal place area (PPA) - scenes or space
What is fMRI?
functional magnetic resonance imaging
* non invasive neuroimaging technique
* exerts a strong magnetic field
* can estimate neural activity by detecting changes in blood oxygenation
* blood flow is positively associated with neural activity in brain
What is prosopagnosia?
- face blindness, difficulty recognizing faces
- patients with face blindness showed lower FFA activity when viewing faces compared to healthy controls
When does binocular rivalry occur?
when 2 eyes receive different images, and the brain cant combine them
see right and left eye images but not both at the same time
What happens if you show 2 diff images into 2 diff eyes independently? a house and a face?
when perceiving the house - PPA activity increase
when perceiving the face - FFA activity increase
while the images remained the same on the retina, observers perceived just the face or just the house, and these perceptions alternated back and forth every few seconds.
showed FFA/PPA activity is driven by perception not the existence of the stimulus
What is the expertise hypothesis?
- we are good in perceiving faces because we’ve been exposed to them for out entire lives
- greebles used as artificial faces
- after training, the FFA showed similar activity when recognizing greebles and humans faces
- support the expertise hypothesis
- FFA might not be a face area but may represent any object with which the person is an expert
What is the developmental curve of face recognition?
- an 8 week old infant already has some basic face recognition ability
- a 3 month old infant can tell facial emotions
- development of face perception continues into adulthood
- human faces are among the most important stimuli in an infants environment
