A person who laughs one minute and cries the next without any clear stimulus is said to have

Affect is the subjective and immediate experience of emotion attached to ideas or mental representations of objects. Affect has outward manifestations that can be classified as restricted, blunted, flattened, broad, labile, appropriate, or inappropriate. Labile affect is affective expression characterized by rapid and abrupt changes, unrelated to external stimuli. incongruent affect is seen in schizophrenia where the patient's thought and emotion are not connected split personality is a common name for dissosiative personality disorder Reference: Kaplan & Sadock's Comprehensive Textbook of Psychiatry, Volume 3, 10th Edition, Pg.4558, 4591. Kaplan & Sadock's synopsis Psychiatry, 11th Edition, Pg.308