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How collective memories can sometimes be inaccurate: Investigating the Mandela Effect

Updated: Jul 6

Can you tell which of these images is the correct depiction of the Monopoly man? 

the mandela effect

How confident are you? 

Hold on to that thought, we’ll come back to it in a moment.

The Mandela Effect (sometimes misspelled "mandella effect", "madela effect" or "mendela effect") is a phenomenon whereby large numbers of people appear to have the same memory that does not match reality. It’s name comes from an allegedly common false ‘memory’: that former South African President Nelson Mandela died in prison during the 1980s. In reality, he passed away in 2013, long after his release from prison and after serving as President of South Africa. The term ‘the Mandela Effect’ was coined by Fiona Broome, a self-identified "paranormal consultant," who reported that she, along with other people, appeared to share this incorrect “memory” of Mandela's death. She proposed a rather spooky explanation for the phenomenon, which we critically evaluate below.

So, is this effect real? If so, what causes it?

A recent study found evidence of a visual Mandela effect, reflecting apparent collective false memories of images. For example, consider the monopoly Mandela Effect, represented by Mr. Monopoly man shown above. The correct depiction is the left-most one: the Monopoly man never wore glasses or a monocle, but lots of people are confident that they remember him as he is depicted in the right-most image, wearing a monocle.

As part of our Transparent Replications project, which aims to run replications of published psychology papers from top journals shortly after they are published, we ran a replication of this study.

Is the Mandela Effect real? It absolutely is. When we re-ran the study from scratch on a new set of participants we found the same effects as the original paper. How was it shown that this effect exists, and why does it exist? In this article, we’re going to explain our replication study and think critically about some explanations for this strange phenomenon.

If you’re just interested in the discussion of what might cause the Mandela effect, feel free to skip ahead and read the sections titled “What Explains the Mandela Effect?” and “Applying Theory Selection Principles”.

Our Study of the Mandela Effect

In order to determine whether an image counts as an instance of the Visual Mandela Effect, researchers Prasad and Bainbridge have proposed the following criteria:

(a) People often mistake the fake version of the image for the real one (low accuracy in identifying the correct image).

(b) There's a specific, common mistake people make with the image (like thinking the Monopoly man has a monocle).

(c) Many people make the same mistake.

(d) Even if people say the correct image looks familiar, they still often get it wrong.

(e) People are very confident in their wrong answers.

Our study followed the design of the original study that we were seeking to replicate, with some minor differences in order to improve statistical analysis (these are discussed in the full report, which you can read here), and we got the same results. Here’s how it worked.

We rebuilt the original study using our study creation platform GuidedTrack. Then we recruited 393 participants using, each of whom was shown images of 40 popular logos or characters, one at a time. For each of the 40 logos or characters, participants saw three different versions. One of these versions was the original, while the other two versions had subtle differences, such as a missing feature, an added feature, or a change in color.

Here is an example:

the mandela effect

Participants were asked to select which of these three versions was the correct version and then rate:

  • how confident they felt in their choice, 

  • how familiar they were with the image, and 

  • how many times they had seen the image before.

In the case of the Tom (from Tom & Jerry) image above, the right-hand image is the correct one. Did you get it right? How confident were you?

If the participants, as a group, chose one particular incorrect version of an image statistically significantly more often than they chose the correct version of an image (which we determined using a χ2 goodness-of-fit test), that was considered evidence of criteria (a), (b), and (c) being satisfied.

This chart shows the ratios of responses by participants:

the mandela effect study

For 8 of the 40 images, the Manipulation 1 version was chosen statistically significantly more often than the Correct version, and there were no images for which the Manipulation 2 version was chosen more often than the Correct version.

To test criteria (d) and (e), we (following the original study authors) conducted permutation tests (for details of what these involved, see the full study report). 

Our findings replicated the findings of the original study: we found that 8 images qualified as cases of the Visual Mandela Effect. Those 8 images were the monopoly man and Tom (from Tom & Jerry), which we have already seen above, and the following 6  - can you tell which are the correct versions?

the mandela effect exercise

the mandela effect exercise

Go to the end of this article to find out!

What explains the Mandela Effect?

Some people entertain quite fantastical explanations for the effect. For instance, the self-identified ‘paranormal consultant’ who coined the term ‘Mandela Effect’ says (taken from her website):

"At first, I thought the only Mandela Effect was the curious coincidence of others recalling what they’d believed was Nelson Mandela’s funeral, but in the 1980s or 1990s...

Once more stories and alternate memories started flooding in, I started leaning in the direction of parallel realities. That fits with some of my ghost research, and what other, similar investigators have encountered, but aren’t always willing to speak about. Not in public, anyway."

This appears to be an allusion to the theory that there is a universe in which Nelson Mandela died in prison, and that we, somehow, have memories from that alternate universe - perhaps because we have somehow crossed over from that one into this one, where he survived and became President of South Africa. 

A popular theory among some people who like to discuss the Mandela Effect (but not a popular theory among scientists) even goes so far as to suggest that the mechanism for this changing of realities is the Large Hadron Collider (particle accelerator) at CERN in Switzerland. On this view, when the large hadron collider is turned on, we jump from one universe or timeline into another and our reality changes.

We think the following explanation is much better.

Our brains use our existing knowledge and expectations to interpret new experiences and encode memories. This can lead to memories being unintentionally altered or distorted to fit our pre-existing beliefs and assumptions about how things are supposed to be.

A key factor in this is that memory is not a perfect recording device. When you remember something, you are not simply retrieving a recording that was stored in your brain; you are reconstructing the event based on prior experiences in a way that is subject to a variety of errors.

One such influence comes from schemas and stereotypes. We have mental templates (schemas) about common objects, situations, and stereotypes that can shape what details get noticed, encoded, and remembered versus which ones get ignored or distorted.

So, you might think that the monopoly man once had a monocle (a common example of the Visual Mandela Effect) because the schema or stereotype of a wealthy man from that era whose attire displays his wealth includes a monocle, and your brain draws on that knowledge when it reconstructs your memory of the monopoly man. This would also explain why people have the same false memory of the monopoly man (and other instances of the Mandela Effect): because we all grow up learning many of the same stereotypes and schemas from our culture(s).

In addition, memories (especially older ones) are highly malleable and can be reshaped by misleading information provided after the fact, leading to the creation of inaccurate or false memories. Plenty of experiments have demonstrated this fact. A classic is Loftus and Palmer (1974), which showed that the wording of a question can distort eyewitness memory. Participants watched a video of a car accident and were asked "About how fast were the cars going when they smashed/collided/bumped/hit into each other?" Those who heard the word "smashed" estimated higher speeds than those who heard "bumped" and were more likely to falsely remember broken glass in the video a week later. (If you want to see how your memory fares with tests like this, try our Is Your Memory Like A Photograph? test!)

One more factor potentially at work with the Mandela effect is compression. If you go to a doctor’s office and then later try to recall what it looked like, you might recall the windows had curtains, but not recall what sort, so your brain quickly guesses with typical sorts of curtains. That is, our brains quickly (and without us realizing) fill in unremembered details with what’s typical based on experience. If the curtains were actually unusual, this could make your memory inaccurate. 

To see a thorough comparison of these two explanations, using philosophical principles of theory selection, see this follow-up article we've written. It shows, in detail, precisely why we think the psychological explanation is better than the parallel worlds one, and offers a handy set of criteria for comparing almost any types of theories to each other.

Before you leave, don't forget to check the right answers (below) to the Mandella effect quiz we gave you earlier.

Finally, if you’d like to explore your own memory in more detail, we have a free, interactive tool that will help you discover whether you retain a faithful representation of the events you witness with two quick memory tests:


Correct responses to the Visual Mandela Effect prompts

the mandela effect exercise results

1 Comment

Jun 20

the TRUMP or MAGA effect

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