Object Recognition. Flashcards
Give 4 reasons why people might fail to recognise and object.
Sensory deficit - acuity, field cut, loss of colour vision.
Knowledge deficit - Alzheimers.
Name deficit - anomia.
Unable to perceive objects - agnosia.
In patients with optic ataxia, what do they struggle with?
Reaching for objects and adjusting their grasp.
There are two streams that leave the primary visual cortex, what are they? Where do they terminate and what are they associated with?
Dorsal and ventral stream. Dorsal stream projects to the posterior parietal cortex and the ventral stream projects to the inferotemporal cortex. Dorsal stream codes info for where and ventral stream codes info for what (visual agnosia)
Do patients with visual agnosia have a sensory, naming or memory deficit?
No.
Can a patient with visual agnosia recognise objects when they are placed in front of them?
No.
Can a patient with visual agnosia define objects, recognise them from a description, or describe an objects physical appearance from memory?
Yes.
What are the two subtypes of agnosia?
Apperceptive and Associative.
What is apperceptive agnosia?
Deficit in computing a structural description.
Where are the lesions in the brain for apperceptive agnosia
Inferior occipital-temporal regions.
What perceptual deficits are seen in a patient with apperceptive agnosia?
Edge grouping, feature binding and view normalisation. Fail tasks such as - abnormal view test, objects presented under different lighting conditions, fragmentary drawings, overlapping figures.
Associative agnosia is what?
A failure to access semantic representation. Can see the whole form of shapes but still can’t recognise them. Therefore have no problem copying figures but can’t tell you what they have copied.
