What can a fifty year old mathematical mishap teach us about science?

What is it about?

Scientists prominently argue that the COVID-19 pandemic stems not least from people’s inability to understand exponential growth. They increasingly cite evidence from a classic psychological experiment published some 45 years prior to the first case of COVID-19. Despite—or precisely because of—becoming such a canonical study (more often cited than read), its critical design flaws went completely unnoticed. They are discussed here as a cautionary tale against uncritically enshrining unsound research in the “lore” of a field of research. In hindsight, this is a unique case study of researchers falling prey to just the cognitive bias they set out to study—undermining an experiment’s methodology while, ironically, still supporting its conclusion.

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Photo by Mihály Köles on Unsplash

Photo by Mihály Köles on Unsplash

Why is it important?

Understanding how humans process time series data is more pressing now than ever amid a progressing pandemic. Current research draws on some fifty years of empirical evidence on laypeople’s (in-)ability to extrapolate exponential growth. Yet even canonized evidence ought not to be trusted blindly. As a case in point, I review a seminal study that is still highly (even increasingly) cited, although seriously flawed. This case serves as both a reminder of how readily even experienced, well-meaning researchers underestimate exponential dynamics, and an admonition for subsequent researchers to critically read and evaluate the research they cite in order to catch and correct errors quickly rather than carry them forward over decades.