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Probabilistic Contextuality in Physics and Human Behavior

Ehtibar Dzhafarov ( Purdue University )
I will present an abstract theory of contextuality in arbitrary systems of measurements. My colleagues and I call the theory Contextuality-by-Default (CbD). It is essentially about how the identity of the measurements of a given set of “properties” changes in different contexts (measurement conditions). The identity of a measurement is understood in the sense of a logically consistent (and empirically unfalsifiable) version of Kolmogorov’s probability theory involving stochastically unrelated random variables. CbD allows for what we call inconsistent connectedness, involving experimental errors and interactions (“signaling”) that may cause the measurements of one and the same property in different contexts to have different distributions. CbD translates into a criterion of (necessary and sufficient conditions for) contextuality in a broad class of systems, including the intensively studied in quantum physics Klyachko-Can-Binicioğlu-Shumvosky-type, EPR-Bell-type, and Leggett-Garg-type systems as special cases. Using this criterion one can establish contextuality in real quantum physics experiments with inconsistent connectedness. By contrast, a wide variety of behavioral data (in the areas of psychophysics of matching, visual illusions, conceptual comprehension, and polls of public opinion) exhibit no contextuality and can be explained by “signaling” alone. Time permitting, I will discuss serious methodological problems in dealing with social data, due to the fact that contextuality can be obtained trivially by averaging over sufficiently diverse patterns of noncontextual responses.


Dzhafarov, E.N., & Kujala, J.V. (in press). Conversations on contextuality. In E.N. Dzhafarov et al. (Eds). Contextuality from Quantum Physics to Psychology. World Scientific Press. (available as arXiv:1508.00862.)

Dzhafarov, E.N., Kujala, J.V., Larsson, J.-Å., & Cervantes, V.H. (in press). Contextuality-by-Default: A brief overview of ideas, concepts, and terminology. Lecture Notes in Computer Science. (available as arXiv:1504.00530.)


Dzhafarov, E.N., & Kujala, J.V., & Larsson, J.-Å. (2015). Contextuality in three types of quantum-mechanical systems. Foundations of Physics 7, 762-782.

Dzhafarov, E.N., Zhang, R., & Kujala, J.V. (in press). Is there contextuality in behavioral and social systems? Philosophical Transactions of the Royal Society A. (available as arXiv:1504.07422.)



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