Visual Perceptual Processes

These flashcards cover key concepts and terminologies from the notes on Visual Perceptual Processes, including types of agnosias, brain regions involved, and characteristics of various perceptual deficits.

What is agnosia?

Agnosia is a general term for a loss of ability to recognize objects, people, sounds, shapes, or smells, despite the primary sense organ not being impaired.

What is apperceptive agnosia?

Apperceptive agnosia is a failure of object recognition due to perceptual impairments, despite relatively preserved elementary visual functions.

What are the subtypes of apperceptive agnosia according to Farah (1990)?

The subtypes are Apperceptive Agnosia Narrow Sense, Dorsal Simultagnosia, Ventral Simultagnosia, and Perceptual Categorization Difficulty.

What characterizes Apperceptive Agnosia Narrow Sense?

It involves adequate visual functions and cognitive ability but impaired shape discrimination.

What are common visual abilities preserved in Apperceptive Agnosia Narrow Sense?

Normal acuity, color vision, depth perception, and fixation maintenance.

What is the main issue in Dorsal Simultagnosia?

Although patients have full visual fields, they behave as if blind, struggling to identify multiple stimuli.

What three syndromes is Dorsal Simultagnosia contextualized in?

Balint's syndrome, which includes inability to direct eye movements, optic ataxia, and attention deficits.

How is Ventral Simultagnosia different from Dorsal Simultagnosia?

Ventral Simultagnosia allows recognition of multiple objects given enough time, whereas Dorsal does not.

What deficit is characteristic of Perceptual Categorization Deficit?

Great difficulty matching 3-D objects across shifts of perspective.

What will a patient with Associative Agnosia likely experience?

Impairments in general semantic knowledge not confined to visual modality and recognition of visually presented objects.

What is another name for Associative visual object agnosia?

Associative Agnosia in the narrow sense.

What are the three criteria for Associative visual object agnosia?

Difficulty recognizing objects, normal recognition in other modalities, and intact visual perception.

What is prosopagnosia?

A condition characterized by impaired recognition of faces while often preserving recognition of other objects.

What does pure alexia affect?

It impairs the ability to read despite normal visual capabilities and the ability to understand spoken language.

What type of deficits are observed in category specific deficits?

Deficits in recognizing living versus non-living objects, alongside verbal deficits.

What neurological issues are associated with prosopagnosia?

Lesions in the right hemisphere, often accompanied by visual field impairments.

What psychological phenomenon is Capgras delusion?

A belief that a loved one has been replaced by an impostor, showing recognition without a feeling of familiarity.

What is the relationship between cognition and awareness in prosopagnosia?

Patients can recognize familiar faces unconsciously, as indicated by psychophysiological measures.

What is the visual perception task performance of a patient with Associative visual object agnosia?

May copy objects line-by-line slowly but struggle with matching or recognizing complex patterns.

What are visual-gnostic categories according to Konorski?

Categories include small manipulative objects, larger partially manipulative objects, human faces, and emotional expressions.

What brain region is primarily affected in cases of pure alexia?

Damage to the left occipital lobe, leading to reading difficulties.

How is apperceptive agnosia typically diagnosed?

Through exhibiting severe impairment in recognizing or matching visual stimuli while having intact visual acuity.

What explains the struggle in categorizing objects in patients with perceptual categorization deficits?

Deficit in building object-centered models despite an intact view-centered representation.

What impact do visual field defects have in Apperceptive Agnosia Narrow Sense?

They are typically not responsible for the recognition impairment; patients have roughly normal vision.

What is the effect of external factors like slashes or breaks on patients with Apperceptive Agnosia Narrow Sense?

Their perception of higher order shapes becomes fragile and disrupted.

What spatial factor is essential in understanding Dorsal Simultagnosia?

The independence of form from motion is crucial for structure from motion perception.

What is a key feature of perceived objects in patients with Perceptual Categorization Deficit?

They often struggle to recognize objects from unusual perspectives due to foreshortening.