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Am Psychol. 2013 Dec;68(9):801-13. doi: 10.1037/a0032850. Epub 2013 Jul 15.

The complex dynamics of wishful thinking: the critical positivity ratio.

Author information

Independent Practice.
Department of Physics, New York University.
Graduate College of Psychology and Humanistic Studies, Saybrook University.


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.

[Indexed for MEDLINE]

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