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“Like a harbor clotted with sunken vessels”: update

A few years ago I reported on this story:

In 2005, Michael Kosfeld, Markus Heinrichs, Paul Zak, Urs Fischbacher, and Ernst Fehr published a paper, “Oxytocin increases trust in humans.” According to Google, that paper has been cited 3389 times.

In 2015, Gideon Nave, Colin Camerer, and Michael McCullough published a paper, “Does Oxytocin Increase Trust in Humans? A Critical Review of Research,” where they reported:

Behavioral neuroscientists have shown that the neuropeptide oxytocin (OT) plays a key role in social attachment and affiliation in nonhuman mammals. Inspired by this initial research, many social scientists proceeded to examine the associations of OT with trust in humans over the past decade. . . . Unfortunately, the simplest promising finding associating intranasal OT with higher trust [that 2005 paper] has not replicated well. Moreover, the plasma OT evidence is flawed by how OT is measured in peripheral bodily fluids. Finally, in recent large-sample studies, researchers failed to find consistent associations of specific OT-related genetic polymorphisms and trust. We conclude that the cumulative evidence does not provide robust convergent evidence that human trust is reliably associated with OT (or caused by it). . . .

Nave et al. has been cited 101 times.

OK, fine. The paper’s only been out 3 years. Let’s look at recent citations, since 2017:

“Oxytocin increases trust in humans”: 377 citations
“Does Oxytocin Increase Trust in Humans? A Critical Review of Research”: 49 citations

OK, I’m not the world’s smoothest googler, so maybe I miscounted a bit. But the pattern is clear: New paper revises consensus, but, even now, old paper gets cited much more frequently.

What’s happened since then? Here’s a quick look at total citations:

The old paper with the false conclusions is increasing its lead! Since 2019, Google says “about 440” citations for the old paper, “about 64” for the new one. So the ratio is improving, but still.

I also came across this:

A registered replication study on oxytocin and trust

Carolyn H. Declerck, Christophe Boone, Loren Pauwels, Bodo Vogt & Ernst Fehr

In an influential paper, Kosfeld et al. (2005) showed that intranasal administration of oxytocin (OT) increases the transfers made by investors in the trust game—suggesting that OT increases trust in strangers. Subsequent studies investigating the role of OT in the trust game found inconclusive effects on the trusting behaviour of investors but these studies deviated from the Kosfeld et al. study in an important way—they did not implement minimal social contact (MSC) between the investors and the trustees in the trust game. Here, we performed a large double-blind and placebo-controlled replication study of the effects of OT on trusting behaviour that yields a power of more than 95% and implements an MSC condition as well as a no-social-contact (NoC) condition. We find no effect of OT on trusting behaviour in the MSC condition. Exploratory post hoc analyses suggest that OT may increase trust in individuals with a low disposition to trust in the NoC condition, but this finding requires confirmation in future research.

There’s nothing wrong with people publishing research that turns out to be mistaken. No problem at all. Sometimes you can’t know a path is a dead end until you walk down it.

The problem is not (necessarily) with the original study. The problem is with a scientific culture that doesn’t have a good way of letting go of these mistakes. Like a harbor clotted with sunken vessels.

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