Anosognosia is an interesting agnosia.

It is, basically, the inability to perceive a disability.

For instance, in hemiparesis (weakness/paralysis in one side of the body), about 18% of the time people do not notice this. That's anosognosia.

Anton's Blindness is a specific type of anosognosia: despite possibly missing eyes, a person is absolutely convinced they can still see. It is self-evident, to them, that they are sighted.

Anosognosia can range from being unaware that you are blind, to being unaware that you are paralyzed, to being unaware that you are incapable of perceiving everything to the left.

Anosognosia is, basically, an agnosia regarding agnosias.

It's not denial. An anosognosiac person perceives, fully and completely, as clear as the nose on their face, that they are not impaired.

In Capgras delusion, a person may fully perceive a loved one as an imposter. They will get agitated and distressed at this self-evident perception that they are being misled.

In 10% of people with Capgras, they do not *notice* that they perceive people as imposters.

Which means: a person who perceives, as clearly and inarguably as the fact that they are still alive, that their spouse is an imposter.

But, who is not aware that they perceive their spouse as an imposter.

They would strenuously deny as absurd the idea that they perceive their wife as an imposter, as if you'd told them they were blind. It's self-evident that their wife is their wife.

And yet: they still have Capgras. They still distance, alienate, accuse of being an imposter, get agitated, experience deep unease, etc.

But for each of that, there is another explanation that is not "you have Capgras, you perceive her as an imposter."

They may become violent, disoriented, due to their perception of a loved one having been for some reason replaced with an imposter.

But, shown video of them behaving this way, they will explain this behaviour perfectly innocuously.

They will calmly explain their behaviour the same way a person with Anton's Blindness who has had their eyes surgically removed, will explain not noticing the chair in the center of the room they bumped against.

Anosognosia can occur with nearly any other agnosia. It occurs with aphasias: you may be absolutely convinced you are speaking normally, despite having severe broca's aphasia.

It can occur with hemilateral neglect, akinetopsia, etc.

It's important to understand that anosognosia is not denying that one, for instance, has Pure Word Deafness and cannot perceive spoken words.

It is being absolutely unable to perceive that this is occurring.

A tangent: Pure Word Deafness is a type of agnosia called Auditory Verbal Agnosia.

It is, basically, the inability to perceive spoken language despite normal hearing.

The exact etiology is still unknown, it occurs after encephalitis, Landaui-Kleffner syndrome, brain trauma

A person who has Pure Word Deafness can hear music, birdsong, tones, etc. Their hearing is not impaired.

However, spoken language is not perceived as distinct phonemes. It's not perceived as speech.