Threat detection: behavioral practices in animals and humans.

In contrast to a perceptible threat that releases freezing, fleeing and fighting, abstract potential threat elicits anxiety and vigilance. The prevalent view is that the larger the animal groups the lower the individual vigilance. Vigilance is a reflection of anxiety, and here we show that anxiety is contagious in grouped social animals. In humans, anxiety frequently results in rituals that confer a sense of controllability and thereby a means to cope with anxiety. Accordingly, in mental disorders with sustained anxiety, rituals predominate the behavior and consequently reduce functionality. Finally, the adaptive value of precautionary behavior, including rituals, lies in providing individuals with the opportunity to practice defensive means safely, and thus to prepare for the eventuality of real danger. Accordingly, the prevalence of anxiety in human and animal behavior accords with the "better safe than sorry" principle.