 Sixthly, research in experimental psychology suggests that fact-finders do not evaluate pieces of evidence one-by-one and in the unidirectional manner required under the mathematical model (Amaya 2015: 114–5). A holistic approach is taken instead where the discrete items of evidence are integrated into large cognitive structures (variously labelled as “mental models”, “stories”, “narratives” and “theories of the case”), and they are assessed globally against the legal definition of the crime or civil claim that is in dispute (Pennington and Hastie 1991, 1993; Pardo 2000). The reasoning does not progress linearly from evidence to a conclusion; it is bi-directional, going forward and backward: as the fact-finder’s consideration of the evidence inclines him towards a particular verdict, his leaning towards that conclusion will often produce a revision of his original perception and his assessment of the evidence (Simon 2004, 2011).