It is not due to a deficit in vision (acuity, visual field, and scanning), language, memory, or intellect.
At an apperceptive level, the features of the visual information from the retina are put together to form a perceptual representation of an object.
[4] Within any given patient, a variety of symptoms can occur, and the impairment of ability is not only binary but can range in severity.
For example, Patient SM is a prosopagnosic with a unilateral lesion to left extrastriate cortex due to an accident in his twenties who displays behavior similar to congenital prosopagnosia.
Damage to specific areas of the ventral stream impair the ability to recognize certain categories of visual information, such as the case of prospagnosia.
[9] One of the tasks she was tested on required her to place a card through a thin slot that could be rotated into all orientations.
An area in the fusiform gyrus of the temporal lobe that has been strongly associated with a role in facial recognition.
[6] The parahippocampal place area (PPA) of the limbic cortex has been found to be activated by the sight of scenes and backgrounds.
[6] Cerebral achromatopsia (the inability to discriminate between different hues) is caused by damage to the V8 area of the visual association cortex.
[6] The left hemisphere seems to play a critical role in recognizing the meaning of common objects.
[11] Apperceptive agnosia is failure of object recognition even when the basic visual functions (acuity, color, motion) and other mental processing, such as language and intelligence, are normal.
[9] The brain must correctly integrate features such as edges, light intensity, and color from sensory information to form a complete percept of an object.
[citation needed] Associative agnosia is an inability to identify objects even with apparent perception and knowledge of them.
[9] Individuals with associative agnosia can copy or match simple figures, indicating that they can perceive objects correctly.
[citation needed] Although visual agnosia can be general, there exist many variants that impair recognition of specific types.
experienced many cognitive issues, mood swings, poor memory, and temper outbursts.
He was able to complete a master's degree in history, later working as a manager at a large corporation.
Associative agnosic patients cannot create a detailed representation of the visual world in their brains, they can only perceive elements of whole objects.
It should not be surprising then that his visual imagery for object size, shape, and color is intact.
to imagine a scenario where a 'B' is rotated 90 degrees to the left, a triangle is put below, and the line in the middle is removed.