 According to popular neuropsychological accounts, delusions are the result of an unusual perceptual experience (Maher 1974); an unusual experience accompanied by reasoning biases (Garety and Freeman 1999; Garety et al. 2001; McKay 2012); a breakdown of certain aspects of perception and cognition including a deficit in hypothesis or belief evaluation (Langdon and Coltheart 2000, Coltheart et al. 2010); or a failure of predictive coding (Fletcher and Frith 2009; Corlett et al. 2010). 