Photo: Thomas Lefebvre / Unsplash
Many people believe at least one conspiracy theory. And that is not necessarily a bad thing - conspiracies do happen.
To take just one example, the CIA really did engage in illegal experiments in the 1950s to identify drugs and procedures that might produce confessions from captured spies.
However, many conspiracy theories are not supported by evidence, yet still attract believers.
For example, in a previous study, we found about 7 percent of New Zealanders and Australians agreed with the theory that visible trails behind aircraft are "chemtrails" of chemical agents sprayed as part of a secret government program. That is despite the theory being roundly rejected by the scientific community.
The fact that conspiracy theories attract believers despite a lack of credible evidence remains a puzzle for researchers in psychology and other academic disciplines.
Indeed, there has been a great deal of research on conspiracy theories published in the past few years. We now know more about how many people believe them, as well as the psychological and political factors that correlate with that belief.
But we know much less about how often people change their minds. Do they do so frequently, or do they to stick tenaciously to their beliefs, regardless of what evidence they come across?
From 9/11 to Covid
We set out to answer this question using a longitudinal survey. We recruited 498 Australians and New Zealanders (using the Prolific website, which recruits people to take part in paid research).
Each month from March to September 2021, we presented our sample group with a survey, including ten conspiracy theories, and asked them how much they agreed with each one.
All of these theories related to claims about events that are either ongoing, or occurred this millennium: the September 11 attacks, the rollout of 5G telecommunications technology, and Covid-19, among others.
While there were definitely some believers in our sample, most participants disagreed with each of the theories.
The most popular theory was that "pharmaceutical companies ('Big Pharma') have suppressed a cure for cancer to protect their profits". Some 18 percent of the sample group agreed when first asked.
The least popular was the theory that "Covid-19 'vaccines' contain microchips to monitor and control people". Only 2 percent agreed.
Conspiracy beliefs probably are not increasing
Despite contemporary concerns about a "pandemic of misinformation" or "infodemic", we found no evidence that individual beliefs in conspiracy theories increased on average over time.
This was despite our data collection happening during the tumultuous second year of the Covid-19 pandemic. Lockdowns were still happening occasionally in both Australia and New Zealand, and anti-government sentiment was building.
While we only tracked participants for six months, other studies over much longer time frames have also found little evidence that beliefs in conspiracy theories are increasing over time.
Finally, we found that beliefs (or non-beliefs) in conspiracy theories were stable - but not completely fixed. For any given theory, the vast majority of participants were "consistent sceptics" - not agreeing with the theory at any point.
There were also some "consistent believers" who agreed at every point in the survey they responded to. For most theories, this was the second-largest group.
Yet for every conspiracy theory, there was also a small proportion of converts. They disagreed with the theory at the start of the study, but agreed with it by the end. There was also a small proportion of "apostates" who agreed with the theory at the start, but disagreed by the end.
Nevertheless, the percentages of converts and apostates tended to balance each other pretty closely, leaving the percentage of believers fairly stable over time.
Inside the 'rabbit hole'
This relative stability is interesting, because one criticism of conspiracy theories is that they may not be "falsifiable": what seems like evidence against a conspiracy theory can just be written off by believers as part of the cover up.
Yet people clearly do sometimes decide to reject conspiracy theories they previously believed.
Our findings bring into question the popular notion of the "rabbit hole" - that people rapidly develop beliefs in a succession of conspiracy theories, much as Alice tumbles down into Wonderland in Lewis Carroll's famous story.
While it is possible this does happen for a small number of people, our results suggest it is not a typical experience.
For most, the journey into conspiracy theory belief might involve a more gradual slope - a bit like a real rabbit burrow, from which one can also emerge.
* Matt Williams is a senior lecturer of psychology at Massey University, John Kerr is a senior research fellow at Otago University and Mathew Marques is a senior lecturer in social psychology at La Trobe University
This story was originally published by The Conversation.