Agnosia
Agnosia is the inability to process sensory information. Often there is a loss of ability to recognize objects, persons, sounds, shapes, or smells while the specific sense is not defective nor is there any significant memory loss. It is usually associated with brain injury or neurological illness, particularly after damage to the occipitotemporal border, which is part of the ventral stream. Agnosia only affects a single modality, such as vision or hearing. More recently, a top-down interruption is considered to cause the disturbance of handling perceptual information.
Tip of the tongue
Anomic aphasia is the inability to recall words and names and is a common symptom of patients with Aphasia and Alzheimer's disease (AD). Research has been conducted to find out how these particular diseases affect TOTs in these individuals. In a study by Beeson, Holland, and Murray (1997), participants with Alzheimer's disease and three classic aphasic syndromes (Broca’s, anomic, and conduction aphasia) were instructed to name famous people. Those with anomic aphasia showed to be superior to the other groups in their ability to naming famous people that were presented. This finding was expected as the group has relatively mild aphasia. However, the Broca’s conduction and AD groups did not differ in immediate or delayed naming of famous faces. All of the groups provided some basic identifying semantic information for at least half of the items presented, suggesting a fair number of items potentially in TOT. Conduction and Broca’s groups showed strongest evidence of TOT, performing better than the other groups in identification of initial letters.