title: New fundamental evidence of non-classical structure in the combination of natural concepts.
abstract: We recently performed cognitive experiments on conjunctions and negations of two concepts with the aim of investigating the combination problem of concepts. Our experiments confirmed the deviations (conceptual vagueness, underextension, overextension etc.) from the rules of classical (fuzzy) logic and probability theory observed by several scholars in concept theory, while our data were successfully modelled in a quantum-theoretic framework developed by ourselves. In this paper, we isolate a new, very stable and systematic pattern of violation of classicality that occurs in concept combinations. In addition, the strength and regularity of this non-classical effect leads us to believe that it occurs at a more fundamental level than the deviations observed up to now. It is our opinion that we have identified a deep non-classical mechanism determining not only how concepts are combined but, rather, how they are formed. We show that this effect can be faithfully modelled in a two-sector Fock space structure, and that it can be exactly explained by assuming that human thought is the superposition of two processes, a 'logical reasoning', guided by 'logic', and a 'conceptual reasoning', guided by 'emergence', and that the latter generally prevails over the former. All these findings provide new fundamental support to our quantum-theoretic approach to human cognition.
authors.affiliation: Center Leo Apostel (CLEA), Vrije Universiteit Brussel (VUB), Krijgskundestraat 33, Brussels 1160, Belgium.
authors.forename: D
authors.initials: D
authors.lastname: Aerts
authors.affiliation: School of Management and IQSCS, University of Leicester, University Road, Leicester LE1 7RH, UK ss831@le.ac.uk.
authors.forename: S
authors.initials: S
authors.lastname: Sozzo
authors.affiliation: Department of Mathematics, University of British Columbia, Kelowna, Canada V1V 1V7.
authors.forename: T
authors.initials: T
authors.lastname: Veloz
mesh_terms: D003071:Cognition / Q000502:physiology*; D003198:Computer Simulation; D003210:Concept Formation / Q000502:physiology; D017143:Fuzzy Logic; D006801:Humans; D008959:Models, Neurological; D015233:Models, Statistical; D011789:Quantum Theory; D013850:Thinking
keywords: cognition; concept formation; concept theory; quantum modelling