Speech perception
Agnosia is "the loss or diminution of the ability to recognize familiar objects or stimuli usually as a result of brain damage". There are several different kinds of agnosia that affect every one of our senses, but the two most common related to speech are speech agnosia and phonagnosia.
Apperceptive agnosia
Apperceptive visual agnosia results in profound difficulties on a patient's ability to recognize visually presented information. Apperceptive agnosia affects the perceptual processing of individuals. Impairments of elements such as color and motion makes it difficult to interpret shape or the spatial arrangements of objects. Deficits in apperceptive agnosics have not been linked to deficits in acuity. Additionally, patients have an intact ability to attend to cued stimuli. They have the ability to maintain fixation, reach for moving targets, and write as well. Those with apperceptive agnosia, however, have difficultly copying geometric shapes and letters. In some cases individuals are able to trace letters and shapes with their finger but they are unable to use the technique as a strategy to name objects.