Perseveration is the persistent repetition of a word, phrase, or gesture despite the stopping of the stimulus that led to the word, phrase, or gesture. For example, if a person answers "Boston" to the question "where were you born?" he may then answer "Boston" to the question "can you say the days of the week backwards?" Or he may repeat "Boston" over and over again despite my trying to ask other questions. This shows that the person is unable to switch ideas. The person is usually unaware that he or she is perseverating (it is involuntary). In addition to Alzheimer's disease and other dementias, perseveration may occur in other brain disorders such as schizophrenia or traumatic brain injury.