For instance, if an experimenter were to say DOG aloud, the utterance would activate and inhibit various words within the subjects lexical interface:

DOG activates 3, and inhibits 0 letters in DOG. – +3
DOG activates 2, and inhibits 1 letters in FOG. – +2
DOG activates 1, and inhibits 2 letters in DAN. – +1The consistency of this model to agnosia is shown by evidence that bilateral lesions to the superior temporal sulcus produces pure word deafness (Kussmaul, 1877), or as it is understood today, speech agnosia. Patients with pure word deafness demonstrate the inability to recognize and process speech sounds with normal auditory processing for non-speech sounds below the level of the cortex. Diagnosis
In order to assess an individual for agnosia, it must be verified that the individual does not have a loss of sensation, and that both their language abilities and intelligence are intact. In order for an individual to be diagnosed with agnosia, they must only be experiencing a sensory deficit in a single modality. To make a diagnosis, the distinction between apperceptive and associative agnosia must be made. This distinction can be made by having the individual complete copying and matching tasks. If the individual has a form of apperceptive agnosia they will not be able to match two stimuli that are identical in appearance. In contrast, if an individual has a form of associative agnosia, they will not be able to match different examples of a stimulus.
For example, an individual who has been diagnosed with associative agnosia in the visual modality would not be able to match pictures of a laptop that is open with a laptop that is closed. Pure alexia
Individuals with pure alexia usually have difficulty reading words as well as difficulty with identifying letters. In order to assess whether an individual has pure alexia, tests of copying and recognition must be performed. An individual with pure alexia should be able to copy a set of words, and should be able to recognize letters. Prosopagnosia
Individuals are usually shown pictures of human faces that may be familiar to them such as famous actors, singers, politicians or family members. The pictures shown to the patient are selected to be age and culture appropriate. The task involves the examiner asking the individual to name each face. If the individual cannot name whose face appears in the picture, the examiner may ask a question that would help to recognize the face in the picture. Treatment
For all practical purposes, there is no direct cure. Patients may improve if information is presented in other modalities than the damaged one. Different types of therapies can help to reverse the effects of agnosia. In some cases, occupational therapy or speech therapy can improve agnosia, depending on its cause.Initially many individuals with a form of agnosia are unaware of the extent to which they have either a perceptual or recognition deficit. This may be caused by anosognosia which is the lack of awareness of a deficit.