Affective flattening, sometimes called blunted or flat affect, is a psychological symptom characterized by diminished or absent emotional reactions. It is associated with a number of psychiatric conditions, such as schizophrenia. Affect is the psychological term for the outward display of emotion, such as through gestures, tone of voice, facial expressions, laughter, and tears. Some affective flattening is normal, such as that which occurs as part of the maturation from childhood to adulthood. Different cultures have different standards of the appropriate intensity and manner of emotional display, so it is important to remain culturally sensitive when evaluating affective flattening.
While flat affect is often used to describe a more severely diminished emotional display than blunted affect, both symptoms are a type of affective flattening. Emotional displays and affective flattening can be conceived of as a continuum rather than a set of discrete symptoms, as the appropriate emotional displays vary among cultures, subcultures, and individuals. Evaluating the intensity of a display of emotion is also a subjective experience.
A less extreme version, in which the range of emotional display is mildly limited when compared to the social norm, is known as constricted or restricted affect. Also called alexythymia, constricted affect is considered a personality trait rather than a psychological disorder, though it is associated with psychiatric conditions including autism, post-traumatic stress disorder (PTSD), major depressive disorder (MDD), anorexia, and bulimia. Alexythymia is also a risk factor for a variety of psychiatric disorders.
In addition to affective flattening, abnormal affect may also manifest as incongruous or inappropriately exaggerated displays of emotion. Affect may be appropriately positive or negative, but inappropriate in intensity, such as breaking into tears because of a minor disappointment. Labile affect is characterized by uncontrollable and socially inappropriate laughter, smiling, or tears. It is common in sufferers of brain injury, dementia, and Lou Gehrig disease or amyotrophic lateral sclerosis. Labile affect may also be indicative of attention-deficit hyperactivity disorder (ADHD) in adults.