Four percent of Americans – roughly 12 million people – believe that “lizard people” secretly control the Earth. At least, that was the finding of an infamous 2013 public opinion survey.

Do so many people really believe such outlandish claims? Or do results like these partly reflect people giving silly answers or deliberately skewing surveys for fun?

US psychiatrist Alexander Scott believes the latter plays a significant role.

Using the survey as an example, he coined the term “the Lizardman constant” to describe the idea that a certain amount of noise and trolling will always exist in surveys about unusual beliefs.

As Scott warned: “Any possible source of noise – jokesters, cognitive biases, or deliberate misbehaviour – can easily overwhelm the signal.”

As researchers who study uncommon beliefs such as conspiracy theories, we wanted to investigate how this kind of cheeky trolling can muddy the waters.

Trolls and true believers

Building on earlier Australian research, we surveyed New Zealanders to test how common dishonest or joking responses were in conspiracy theory surveys.

We did this in two ways. First, we directly asked people a yes/no question at the end of the survey:

“Did you respond insincerely at any earlier point in this survey? In other words, did you give any responses that were actually just joking, trolling, or otherwise not indicating what you really think?”

Second, we included in the survey a........

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