Psychological torture, mental torture or emotional torture is a type of torture that relies primarily on psychological effects and only secondarily on any physical harm inflicted. Although not all psychological torture involves the use of physical violence, there is a continuum between psychological torture and physical torture. The two are often used in conjunction with one another and often overlap in practice, with the fear and pain induced by physical torture often resulting in long-term psychological effects and many forms of psychological torture involving some form of pain or coercion.

The Convention against Torture and Other Cruel, Inhuman or Degrading Treatment or Punishment (commonly known as the United Nations Convention against Torture) is an international human rights treaty, under the review of the United Nations, that aims to prevent torture and other acts of cruel, inhuman, or degrading treatment or punishment around the world. The Convention requires states to take effective measures to prevent torture in any state under their jurisdiction and forbids states to transport people to any country where there is a reason to believe torture could occur.

The text of the Convention was adopted by the United Nations General Assembly on 10 December 1984 and following ratification by the 20th state party, it came into force on 26 June 1987. 26 June is now recognized as the International Day in Support of Victims of Torture, in honor of the Convention. As of May 2015, the Convention has 158 state parties.

The Convention gave for the first time in history a definition of psychological torture:

Torture is any act by which severe pain or suffering, whether physical or mental, is intentionally inflicted on a person for such purposes as obtaining from him or a third person information or a confession, punishing him for an act he or a third person has committed or is suspected of having committed, or intimidating or coercing him or a third person, or for any reason based on discrimination of any kind, when such pain or suffering is inflicted by or at the instigation of or with the consent or acquiescence of a public official or other person acting in an official capacity.

The Optional Protocol to such Convention (OPCAT, 2006) is an important addition to the United Nations Convention. The Committee Against Torture (CAT) is a body of independent experts that monitors implementation of the Convention by State parties. All-State parties are obliged under the Convention to submit regular reports to the CAT on how the rights are being implemented. Upon ratifying the Convention, States must submit a report within one year, after which they are obliged to report every four years. The Committee examines each report and addresses its concerns and recommendations to the State party in the form of "concluding observations". Under certain circumstances, the CAT may consider complaints or communications from individuals claiming that their rights under the Convention have been violated. The CAT usually meets in May and November each year in Geneva.

A contemporary definition of psychological torture are those processes that "involve attacking or manipulating the inputs and processes of the conscious mind that allow the person to stay oriented in the surrounding world, retain control and have the adequate conditions to judge, understand and freely make decisions which are the essential constitutive ingredients of an unharmed self". The Torturing Environment Scale is the first scale to measure Torturing Environments based on this model.

Many forms of psychological torture methods attempt to destroy the subject's normal self-image by removing them from any kind of control over their environment, isolation, monopolising of perception, impression of almightiness, creating a state of learned helplessness, psychological regression and depersonalization. Other techniques include humiliation, forced nudity and head shaving, exhausting by sleep deprivation, hooding and other forms of sensory deprivation.