week 5 - perceiving objects and scenes Flashcards
scene
acted within
object
acted upon
what do scenes contain?
- background elements
- objects organized in meaningful ways with each other and the background
Mary Potter experiment
- participants were given a target to find
- shown the objects of target followed by a rapid amount of scenes
What did Mary Potter’s experiment find?
were are able to perceive the gists of scenes even when a picture is only presented for 1/4 seconds
Li Fei-Fei experiment
used masking to show that the overall gist is perceived first followed by details
masking
a stimulus that is shown right after initial stimulus to prevent/reduce imprinting time
What did Fei-Fei’s experiment demonstrate?
we are able to make out the gist of a scene in as little as 60 ms
global image features of scenes
circumstances that allow us to perceive the gist of a scene holistically
What are the types of global image features?
- degree of naturalness
- degree of openness
- degree of roughness
- degree of expansion
- color
degree of naturalness
how natural is the scene?
degree of openness
is the scene open or are there objects
degree of roughness
related to texture
degree of expansion
is scene going beyond the scope of our visual field
regularities
things that occur all the time, therefore, we are better able to perceive them
physical regularities
regularly occurring physical properties
What are the 3 physical regularities?
- oblique effect
- uniform connectedness
- light-from-above heuristic
oblique effect
people perceive horizontals and verticals more easily than other orientations
uniform connectedness
- objects are defined by areas of the same color/texture
- we group and segregate appropriately
light-from-above heuritstic
- light in natural environment comes from above
- affects the way we perceive direction, angles, etc
semantic regularities
relates to meaning of a scene
Palmer experiment
- observers saw a context scene which was briefly followed by target pictures
- prompted to correctly identify each stimuli
What were the results to Palmer’s experiment?
- target congruent with the context were identified 80% of the time
- targets incongruent were only identified 40% of the time
Torrallba experiment
- an image of a blurred object is difficult to identify
- putting the “blob” in a context scene makes it easier to perceive and identify
- relates to semantic regularities
theory of unconscious inference
created by Helmholtz to explain why stimuli can be interpreted in more than one way
likelihood principle
objects are perceived based on what is most likely to have caused the pattern
Grill-Spector Experiment
monitored FFA in participants while showing one of each stimuli per trial (Harrison Ford, random face, random texture) for 50 ms followed by random-pattern mask
What were the results of the Grill-Spector experiment?
- FFA was greatest when Ford stimuli was correctly identified
- less activity in FFA when stimuli was identified as something else
- little FFA response when a face was not identified
What would occur if an optic nerve was damaged?
information from right eye would be cut off
What would occur if an optic chiasm was damaged?
left visual field would be lost
What two aspects are able to disrupt the development of vision?
- depth perception
- binocular rivalry
depth perception
- slightly different input from each eye
- this allows us to perceive distance
binocular rivalry
- brain is unable to perceive two different inputs from each eye
- we usually “switch off” and images do not fuse
Sheinberg and Logothesis experiment
- used primates to show physiological process of binocular rivalry
- monkey was shown two images (one for each eye: butterfly and sunburst)
- recorded neuron in IT cortex
What were the results of the Sheinbergy and Logothetis experiment?
the neuron in the IT cortex responded most to the butterfly
Tong et. al experiment
- used binocular rivalry experiment with house and face
- participant pushed button to indicate perception
What were the results of the Tong experiment?
fMRI showed an increase in activity in
- parahippocampal place area for house
- FFA for face
Kamitani and Tong experiment
- carried on Tong study but with regards to gradings of different orientations
- responses from fMRI voxels were measured
- able to determine a particular patter of voxel activity attributed to each type of grading orientation
What was the orientation decorder able to do?
analyzed voxel activity and able to accurately predict which orientation had been presented
structural and semantic encoding experiment
- different types of imagery shown to determine pattern of voxel activity
- decoder matches target image but did not do a good job at matching structural elements
- semantic information allowed decoder to do a much better job at predicting
fusiform face area (FFA)
responds only to faces
t/f: inverted and upside down faces are much harder to perceive that inverted cars
true
t/f: there is low recognition performance when a low negative face is presented
true
t/f: there is a high recognition performance when the face is negative and the eyes are positive
true
t/f: recognition performance is at its highest when a full-positive face is presented
true
amygdala
activated by emotional aspects of face
superior temporal sulcus (STS)
responds to where the person is looking and to mouth movements
frontal cortex (FC)
activated when evaluating facial attractiveness
Newborn vision experiment
- presented 3 types of visual stimuli to babies who were just born
- measured interest by recording rotation of eyes
- stimulus with face like features had highest response
- stimulus with no features got lowest response
toddler vision experiment
1-2 year olds were given 2 types of stimuli and were prompted to choose a preference between the two
What were the results for toddler vision experiment?
- preference for upright face over upside down face
- preference for top-heavy configuration over bottom-heavy
- no distinct preference for either upright or top-heavy configuration faces
What do the results of the toddler vision experiment suggest?
infants can recognize faces to an extent
