The complex dynamics of wishful thinking: The critical positivity ratio

Nicholas J.L. Brown, Alan D. Sokal, Harris L. Friedman

    Research output: Contribution to journalArticlepeer-review


    We examine critically the claims made by Fredrickson and Losada (2005) concerning the construct known as the "positivity ratio." We find no theoretical or empirical justification for the use of differential equations drawn from fluid dynamics, a subfield of physics, to describe changes in human emotions over time; furthermore, we demonstrate that the purported application of these equations contains numerous fundamental conceptual and mathematical errors. The lack of relevance of these equations and their incorrect application lead us to conclude that Fredrickson and Losada's claim to have demonstrated the existence of a critical minimum positivity ratio of 2.9013 is entirely unfounded. More generally, we urge future researchers to exercise caution in the use of advanced mathematical tools, such as nonlinear dynamics, and in particular to verify that the elementary conditions for their valid application have been met.

    Original languageEnglish (US)
    Pages (from-to)801-813
    Number of pages13
    JournalAmerican Psychologist
    Issue number9
    StatePublished - Dec 2013


    • Broaden-and-build theory
    • Lorenz system
    • Nonlinear dynamics
    • Positive psychology
    • Positivity ratio

    ASJC Scopus subject areas

    • General Psychology


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