Wernicke’s aphasia, also known as receptive aphasia, sensory aphasia, fluent aphasia, or posterior aphasia, is a type of aphasia in which individuals have difficulty understanding written and spoken language because of damage to a distributed network of brain regions involved in language comprehension rather than a single isolated area. Patients with Wernicke’s aphasia often have fluent speech, which is characterized by typical speech rate and effortless speech output, but the content may lack meaning or include incorrect or made-up words. Writing often reflects speech by lacking substantive content or meaning, and may contain paraphasias or neologisms, similar to how spoken language is affected. In most cases, motor deficits (i.e. hemiparesis) do not occur in individuals with Wernicke's aphasia. Therefore, they may produce a large amount of speech without much meaning. Individuals with Wernicke’s aphasia commonly show anosognosia, meaning they may be unaware of their errors in speech and may not realize that their spoken language lacks meaning. They typically remain unaware of even their most profound language deficits.
Like many acquired language disorders, Wernicke's aphasia can be experienced in many different ways and to many different degrees. Patients diagnosed with Wernicke's aphasia can show severe language comprehension deficits; however, this is dependent on the severity and extent of the lesion. Severity levels may range from being unable to understand even the simplest spoken and/or written information to missing minor details of a conversation. Many diagnosed with Wernicke's aphasia have difficulty with repetition in words and sentences and/or working memory.