man holds a smelly fish

Do fishy smells turn us into skeptics?

“Something smells fishy” is a widely accepted metaphor, with variants of it appearing in more than 20 languages worldwide. New research suggests this metaphor actually describes a tendency people have to be suspicious when they smell spoiling fish—an evolved mechanism that helped humans survive for centuries.

While this tendency to be suspicious can have drawbacks by undermining trust in others, researchers say the effect also can support reason and judgment.

“If I’m distrustful, then I’m thinking, ‘Something’s wrong here.’ And then I have to think more critically and figure out what is wrong,” says Norbert Schwarz, the study’s lead author and director of the USC Dornsife Center for Mind and Society.

Schwarz and researchers David Lee and Eunjung Kim from the University of Michigan conducted reasoning experiments to test their suspicion. They asked 31 students to complete a questionnaire in a booth that the researchers had sprayed with fish oil. Separately, 30 other students completed their questionnaires in a booth that didn’t smell fishy.

Among the various questions was a red herring that scientists call the Moses Illusion: “How many animals of each kind did Moses take on the Ark?”

Repeated tests have shown people fail to notice that the Moses Illusion contains misinformation, even if during an experiment, they are forewarned of a potential distortion. Participants consistently answer “two” to this question, even when they know that Noah, not Moses, built the Ark and ferried pairs of animals to safety.

In this latest study, a spritz of fish oil in one booth appears to have prompted many participants to look beyond the illusion and recognize the misinformation.

In the fishy booth, 13 of 31 students (42 percent) detected something amiss with the Moses question. These skeptics responded that they “can’t say” how many animals Moses had taken.

By contrast, their peers in the non-fishy booth were more trusting: Only five of those 30 students—17 percent—noticed the distortion.

Schwarz says he hopes to further explore the “something smells fishy” metaphor and its influence on reasoning.

The smells that trigger suspicion vary from country to country, although in all cases it is generated by rotting food or organic matter, Schwarz says. However, in some countries, the smell of suspicion is not the smell of fish, but could be, for example, a rotten potato.

“We are looking at collaborating with researchers in other countries to learn more about the role of sensory experience in critical thinking,” he adds.

The study was published this month in the Journal of Experimental Social Psychology.

Source: USC