Using a cocktail of magic and fMRI, psychologists implanted thoughts in people’s minds

Can you think a thought which isn't yours? A remarkable new study, led by psychologist Jay Olson from McGill University in Canada, suggests you can. The research, published in Consciousness and Cognition, used a form of stage magic known as "mentalism" to induce the experience of thoughts being inserted into the minds of volunteers. It is an ingenious study, not only for how it created the experience, but also for how it used the psychology lab as both a stage prop and a scientific tool.

Years before he was famous, stage illusionist Derren Brown wrote a book called Pure Effect, where he argued that presenting tricks as "psychology" could be an effective form of misdirection. In his innovative shows, Brown often claims he is debunking psychics by demonstrating how psychology can be used to manipulate people's minds. In practice, his mind-reading and mind control feats can involve the same traditional techniques used by stage magicians, it's just that he presents them as psychology rather than magic.

Olson and his colleagues from McGill took this approach a step further, telling their participants that they were taking part in a study to see if an fMRI brain scanner could read thoughts and influence their mind.

Hidden from the participants was the fact that the experiment was actually conducted in a mock scanner – something that exists in most neuroimaging facilities to test experiments before they are run on the genuine equipment. To add to the plausibility of the story, the participants went through a realistic briefing, safety screening, and calibration procedure for an fMRI brain scan.

Participants were then asked to complete what they thought were "mind reading" and "mind influencing" experiments.

In the "mind reading" stage, researchers asked each participant to lie in the "scanner", silently think of any two-digit number and press a button when they were done. The fMRI machine then produced a number on screen and the researcher could be seen writing the result onto a clipboard.

Next, the participant was asked to name the number they had silently thought of. The researcher turned the clipboard, stunning the participant by showing exactly their number – seemingly "read" from their mind by the power of fMRI.

The researchers are coy about exactly how this was achieved, only referencing an old mentalism book. In fact, they likely used a variation on a technique called the "swami gimmick" where the mentalist – the researcher in this case – has a fake rubber tip on the end of their thumb, which includes a barely visible shard of pencil lead. Earlier, when the researcher appeared to be writing the fMRI "mind reading" results, he was just pretending. What really happened is that, in the split second after the participant announced their secretly selected number, the researcher discreetly wrote it down on the clipboard using their thumb.

In the second, "mind influencing" condition, the participant was told that the machine was programmed to put a number into their mind. This time the researcher "wrote down" the number the machine had chosen to "transmit". As before, the participant was asked to silently think of any two-digit number and after the "scan" the researcher seemed to show that the participant had thought of exactly the number the machine had 'transmitted' to them – using, of course, exactly the same thumb-writing trick as in the mindreading phase.

So here's where the real psychology came in. After the scans, the researchers asked the participants to rate how much control they felt they had over their choice of numbers. Of course, in reality all their choices were completely voluntary, but in the second stage of the experiment, they believed they had less control and that the machine had influenced their thinking. Consistent with this perception, they also took longer to choose a number in the mind influencing condition than in the "mind reading" condition.

The researchers checked whether anyone had worked out what was really happening. A few participants expressed doubts about whether the "fMRI machine" was really influencing them and were removed from the analysis, but none suspected stage magic.

Olson and his colleagues replicated their results using a second experiment, run in exactly the same way, but this time they also interviewed the participants to find out what they'd felt during the procedure. They reported a range of anomalous effects when they thought numbers were being "inserted" into their minds: A number "popped in" my head, reported one participant. Others described "a voice … dragging me from the number that already exists in my mind", feeling "some kind of force", feeling "drawn" to a number, or the sensation of their brain getting "stuck" on one number. All a striking testament to the power of suggestion.

A common finding in psychology is that people can be unaware of what influences their choices. In other words, people can feel control without having it. Here, by using the combined powers of stage magic and a sciency-sounding back story, Olson and his fellow researchers showed the opposite – that people can have control without feeling it.

But the research team's motivations where not purely focused on everyday psychology. In some types of mental health problems, people start to experience their thoughts and actions being controlled by what seem like outside forces. Olson's team hope that their work can provide a way of studying one aspect of this experience, safely and temporarily in the lab, potentially providing a window into how these more debilitating experiences affect the mind and brain.

About the author

Post written by Dr Vaughan Bell (@vaughanbell). Vaughan is a senior clinical lecturer at University College London and a clinical psychologist in the NHS.

Further reading

Olson, J., Landry, M., Appourchaux, K., & Raz, A. (2016). Simulated thought insertion: Influencing the sense of agency using deception and magic Consciousness and Cognition, 43, 11-26 DOI: 10.1016/j.concog.2016.04.010