False confessions can result in heavy legal penalties, including imprisonment and the death penalty. So why do people confess to crimes they did not commit? Extensive research and systematic analysis of real-life cases since the early 1980s, which have shown that false confessions are much more common than previously thought, has provided some answers to this question. First, false confessions are typically caused by a combination of factors rather than a single cause. Second, there are different psychological types of false confession, originally referred to by Kassin and Wrightsman as voluntary, coerced internalised and coerced compliant confessions. Attention deficit hyperactivity disorder is a relevant risk factor to all three psychological types of false confession.