Anger or wrath is an intense emotional response. It is a normal emotion that involves a strong uncomfortable and emotional response to a perceived provocation. Often it indicates when one's basic boundaries are violated. Some have a learned tendency to react to anger through retaliation. Anger may be utilized effectively by setting boundaries or escaping from dangerous situations. Some people describes anger as a normal emotion that involves a strong uncomfortable and emotional response to a perceived provocation. Anger may have physical correlates such as increased heart rate, blood pressure, and levels of adrenaline and noradrenaline. Some view anger as an emotion which triggers part of the fight or flight brain response. Anger becomes the predominant feeling behaviourally, cognitively, and physiologically when a person makes the conscious choice to take action to immediately stop the threatening behaviour of another outside force. The external expression of anger can be found in facial expressions, body language, physiological responses, and at times in public acts of aggression. While most of those who experience anger explain its arousal as a result of "what has happened to them," psychologists point out that an angry person can very well be mistaken because anger causes a loss in self-monitoring capacity and objective observability. Modern psychologists view anger as a primary, natural, and mature emotion experienced by virtually all humans at times, and as something that has functional value for survival. Anger can mobilize psychological resources for corrective action. Uncontrolled anger can, however, negatively affect personal or social well-being. The issue of dealing with anger has been written about since the times of the earliest philosophers, but modern psychologists, in contrast to earlier writers, have also pointed out the possible harmful effects of suppressing anger. Displays of anger can be used as a manipulation strategy for social influence.