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.
Recognition memory
Damage to the temporal lobes can also result in visual agnosia, a deficit in which patients are unable to properly recognize objects, either due to a perceptive deficit, or a deficit in semantic memory. In the process of object recognition, visual information from the occipital lobes (such as lines, movement, colour etc.) must at some point be actively interpreted by the brain and attributed meaning. This is commonly referred to in terms of the ventral, or "what" pathway, which leads to the temporal lobes. People with visual agnosia are often able to identify features of an object (it is small, cylindrical, has a handle etc.), but are unable to recognize the object as a whole (a tea cup). This has been termed specifically as integrative agnosia.