Object Recognition Flashcards
Despite variability, what can we use to recognize that an object is the same one?
Perception and memory
What is visual agnosia?
The inability to recognize objects
How does a visual agnostic figure out what an object is?
Use of other senses and pathways to figure out what an object is
Why can visual agnostics recognize higher level objects?
They require semantic memory
What is the category specific deficit?
Not being able to recognize specific objects in category
What’s the difference between memory loss and agnosia?
People with agnosia can use other senses to recognize objects
What pathway is damaged in visual agnosia?
The “what” pathway
Where is the “What” pathway?
It is in the anterior temporal cortex, towards the bottom o f the brain
What is cellular evidence of the “what” pathway?
A single cell is selectively active to a cell and without the specificity, lose the cell activity
What is optic ataxia?
Unable to recognize the location or object
What is associative agnosia?
Unable to link perceptual information about an object with long term semantic memory about the object
What is apperceptive agnosia?
Unable to recognize an object due to perceptual problems (such as a different viewpoint)
What is the lateralization effect?
Apperceptive agnosia is more common with right hemi damage and associative agnosia is more common with left hemi
What does the right hemisphere focus on in representations?
Global representations
What is the unusual views test used to measure?
Apperceptive agnosia
Where is apperceptive agnosia damage?
In the right posterior of the brain
How does the hemispheric model of recognition work?
Visual analysis moves to perceptual categorization (right) and then to semantic categorization (left)
What is integrative agnosia?
Inability to synthesize a whole object (associative agnosia)
What kind of lesions lead to integrative agnosia?
Bilateral lesions
What is object constancy?
The ability to recognize an object in many orientations and under various conditions
What is the central debate in object recognition?
Whether perception depends on recognizing an object from a certain viewpoint
What do view-dependent theories argue?
Object recognition depends on the vantage point and we have different representations for each vantage point
What do view-invariant theories argue?
Recognition comes from basic properties that are inherent to the object and requires inference
Which agnosia supports the view-dependent theory?
Apperceptive
What is the repetition suppression effect?
We activate the same brain area less with more times of observation
What is the most common example of category specificity in agnosia?
Living vs non-living things
What’s one possible explanation for why an agnosics have a harder time recognizing living things?
There’s a secondary kinesthetic code for man-made objects
What is capgras syndrome?
The ability to recognize a close relative by their face
What is an explanation for why capgras syndrome occurs?
The wire between the emotional limbic system and the visual system is cut off
What is the hierarchical coding hypothesis?
Individual cells respond to high level shapes (face selective cells)
What is the ensemble coding hypothesis?
Ensembles of cells are needed to code for high level shapes
What is a gnostic unit?
A neuron that responds to a specific complex object
How does the hierarchy of the coding hypothesis work?
Each neuron corresponds to an increasingly more complex part of the object
How does the ensemble coding hypothesis work?
Recognition of many simultaneous properties leads to a recognition of a face
What part of the brain is used to recognize faces?
Fusiform gyrus
What is visual prosopagnosia?
The inability to recognize faces
How does prosopagnosia differ from agnosia?
Damage in slightly different brain region
Where does most damage seem to be in visual prosopagnosia?
The right FFA
Where is the fusiform located?
In the bottom right portion of the brain
What area is more activated in recognizing faces?
The right FFA
When is the N170 larger?
In looking at faces
What did the right/left anesthetizing experiment show?
The right FFA is important for face recognition and self recognition
What is the parahippocampal place area?
The PPA is used to identify places and is located very close to the FFA
What is Farah’s two process model for object recognition?
Recognition is based on either a holistic analysis or an analysis by parts depending on what kind of object it is
Who was patient KC?
A patient with integrative agnosia that was not able to recognize objects but was able to recognize faces
What kind of processing is required for faces?
Global - we can recognize a face much better when the whole is presented
What is the scrambled faces experiment?
When faces are scrambled up, we don’t activate the FFA
