chapter 5: perceiving objects and scenes Flashcards
caveat
remember though how easily machines can be fooled
inverse projection problem
task of determining the object responsible for a particular image on the retina, 2D retina, we have to make a prediction or inference of what an object is
viewpoint invariance
seeing the same object from different angles
perceptual organization
the process by which elements in a person’s visual field become perceptually grouped and segregated to create a perception
structuralists
thought of as legos, pieces of what you see are built together
what are the two arguments against structuralism ?
apparent movement and illusory contours
apparent movement
the perception of movement when something is actually stationing
illusory contours
apparent edge, perceiving edges that are not physically present the image
law of continuity
straight or curving lines when connect, partially covered objects still seen as continuing
law of pragnanz
every pattern is seen in such a way that the result is as simple as possible, the simpler the better
law of similarity
similar things appear to be grouped together
law of proximity
things that are near each other appear to be grouped together
law of common fate
things that are moving in the same direction appear to be grouped together
law of common region
elements that are within the same region of space appear to be grouped together
law of uniform connectedness
a connected region of the same property (lightness, color, texture, or motion) is perceived as a single unit
border ownership
shifts with each figure or percept
figure ground segregation
figural cues determine how an image is segregated into figure and ground, lower visual field seen as figure
concave vs convex
areas on the convex side are seen as the figure
neons
shapes or parts of an object that make something whole
at how many seconds can someone start recognizing objects ?
67 ms
what are the global image features ?
- degree of naturalness
- degree of openness
- degree of roughness
- degree of expansion
- color
semantic regularities
characteristics associated with activities that are common in different types of scenes, scene schemas
who developed the theory of unconscious inference ?
helmholtz
unconscious inference
Perception is a result of unconscious assumptions or inferences about the environment, now called prediction
likelihood principle
the object we perceive is the most likely one based on the stimuli received (sensed)
bayesian inference
prior beliefs + reality = conclusion
prior
initial estimate of probability of outcome, belief and expectation
likelihood
available evidence is consistent with outcome
predictive coding
neurons high in the hierarchy are in charge of high level predictions, predicted probabilities → top down processing, if high neurons match low neurons (low probability error), if high neurons don’t match (high probability error)
dorsal pathway
where and how
ventral pathway
what
re-entrant modulation
enhancement of something like an object or sound
induced activity
brain waves not time locked to an activity, not triggered by a stimulus
evoked activity
time locked to stimuli
what are two cases of evoked activity ?
ERPs (event related potentials) and SSVEPs (steady state visual evoked potential)
ERPs (event related potentials)
related to the 5 senses, time locked to a stimulus
SSVEPs (steady state visual evoked potential)
consistent or repetitive stimulation, brain oscillates at same frequency as shown in SSVEPs
what are the four categories the brain visualizes objects ?
scenes, faces, bodies, objects
part of brain related to scenes
PPA, parahippocampal place area
part of the brain related to faces
FFA, fusiform face area
part of the brain related to bodies
EBA, extrastriate body area
part of the brain related to objects
LOC, lateral occipital complex
superior temporal sulcus (STS)
form for motion, voice area, gaze direction, mouth movements, face movements
spatial layout hypothesis
not so much places but instead surface geometry or the geometric layout of a scene
neural mind reading
using a neural response (example through fMRI) to determine what a person is perceiving or thinking
how is neural mind reading done ?
measure voxels (cubes of activity) in the brain, determine a pattern of activity, across multiple voxels in the brain (multivoxel pattern analysis), the decoder then predicts A or B
what part of the brain is modular to what it recognizes ?
EBA, extrastriate body area
