Other influences on his drip technique include the Mexican muralists and Surrealist automatism. Intoxication generally excludes automatism, even when involuntary. The true defences include duress, automatism, intoxication, or necessity. Insanity, automatism, mistake and self defence operate as defences to any offence. A successful automatism defence negatives the "actus reus" element of a crime. In Canada, Marcelle Ferron was an exponent of automatism. Defences based in common law include automatism, and an honest and reasonable mistake of fact. S.C.R. 871 is a leading Supreme Court of Canada decision on the criminal automatism defence. Surautomatism is any theory or act of taking automatism to its most absurd limits. Because automatism is such a comprehensive defence, there are various exclusions to an automatism defence. There are several limitations to the defence of automatism in English law. He was instead required to rely on the defence of automatism. Automatism is a rarely used criminal defence. In "Attorney-General's Reference No 2 of 1992", this definition of legal automatism was confirmed. He suggested that the "tingling" sensation described by Titchener was an example of motor automatism.