My wife was recently telling some mutual friends an amusing anecdote about the time she was changing our then-baby son’s nappy in the toilet of a busy café, only for him to urinate all over the groin region of her trousers, meaning she had to return to the crowded eating area displaying a deeply suspicious stain. Big laughs all round.

It is a very amusing story, in fairness. There’s just one slight problem with it; it never happened. Not to her, at least. It happened to me. I pointed this out, and she was genuinely shocked, and baffled as to how one of my memories could end up in her head. I suggested that it may be because she has many memories of hearing me tell that story multiple times over the years, and also has many memories of changing that specific baby in public places, so it wouldn’t require much effort for her brain to merge the two and create something effectively new. A ‘false memory’, if you like.

You marry a neuroscientist, and this is the sort of thing that’ll happen.

But this is just one example of how flexible human memory is. And that’s when someone isn’t actively trying to distort your memories and understanding. Should we be worried? Are we all prone to, and riddled with, false memories? How much of what we think we remember genuinely happened?

To answer this, consider the following; the term false memories logically implies the existence of ‘true’ memories. Where false memories recall things that definitely didn’t happen, true memories would be reliable and accurate memories of things that did. A straightforward binary distinction. Sadly, the way our brain handles and stores memories is far more complex, and far less logical, than you would hope.

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"Sadly, the way our brain handles and stores memories is far more complex, and far less logical, than you would hope."

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Human memory is not like electronic data on a hard drive, or words chiselled onto stone tablets. Information is stored in the brain via the creation and activity of synapses; the connections between two separate neurons – i.e. brain cells. But cells are not static, they’re alive, and in a constant state of flux, a sort of quasi-stable equilibrium. They respond to stimulation and activity, and adapt accordingly. Because human memory is based on the activity of and between cells, it too becomes plastic and flexible. Partially this is due to the brain ‘recreating’ memories in our recall, building on the more basic information held in the synapses, like someone guessing a crossword answer from the clue and the few letters present. This process has numerous interesting consequences.

For instance, it’s common when telling a story about an amusing event that happened to you, to embellish and exaggerate elements of it for comic effect. That’s very good when regaling your friends at a social gathering, but doing so causes new memories of these embellishments, which are overlaid on top of the original memory.

Ideally it would mean you separately remember the bonus elements you added to the event next time you want to regale others about it, but the human brain is a thrifty organ and generally can’t afford to be so meticulous about how it stores information. It’s incredibly complex, but as a rule of thumb, important information is prioritised over unimportant, or less important sorts.

But what counts as ‘important’ in this context? This is governed by the deeper fundamental processes that we’ve evolved over millions of years, which don’t assign memories importance based on relevance or usefulness, but on how much sensation or emotional value they carry. Of a dull commute that follows the same route day in day out, all memories will blur into one. But did you crash your car on the way to work? That highly-charged, visceral memory will likely stay with you forever, for all that you’d rather it didn’t.

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"A true memory can become gradually more ‘false’ with each retelling, thanks to the way the brain stores our memories."

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Ergo, you recall a memory and tell people about it, and add some elements that make your friends laugh. This will make you happy, and thus your brain will add weight to your new plausible-but-fictitious elements. In this way, a true memory can become gradually more ‘false’ with each retelling, thanks to the way the brain stores our memories. Through the processes of empathy and theory of mind, we can imagine or perceive things from the perspectives of others. Thus, a memory of a story you particularly enjoy and relate to, or one that has many elements familiar to you, can eventually be remembered as if you were there. As my wife found out.

Of course, there’s more to it than this. Existing memories of true events aren’t just replaced by more pleasing memories of fictional things. You may remember doing better in a job interview than you actually did, but you won’t remember getting the job if you in fact didn’t. What’s tangible, what actually occurs, generally carries more weight than the abstract, the imaginary. No doubt we all had rather explicit fantasies about our crushes in our teenage years, but we seldom end up believing these fantasies actually happened. Gradually inflating and adjusting existing memories is one thing, but creating new ones wholesale is another. Our brains are, usually, very good at telling the difference between what happened and what didn’t.

How do they do this? Real events are experienced via our senses, and fictional events are not. So much of our brain, arguably the bulk of it, exists to process and deal with sensory information, the data relayed to us from the outside world via our vision, hearing, taste, smell and touch (and proprioception, thermoception and so on; there are actually far more than 5 senses, neuroscientifically speaking).

The memory processing areas, like the hippocampus in the temporal lobe, consolidate all the brain activity that makes up an experience or event and store it as a memory. If something is actually happening, the memory it creates is going to include far more sensory information than something we dreamed up or were told about second or third hand, and thus such a memory is prioritised. When this distinction between real and imagined breaks down, that’s when things like hallucinations, psychosis and schizophrenia occur.

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"And so it can occur, that fake news and the flexibility of the human brain and memory can coincide, to encourage people to believe things about the world that aren’t true, for the benefit of people who wish the world was other than it is."

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This is important, because our memories and experiences are utilised by our brains to form a mental model of how the world works. It’s reassuring to believe that we’re always completely objective and rational, but this is just a helpful delusion. It’s not that we can’t be totally rational and logical, it’s just we live in a non-stop, bafflingly-complex world, and 100% logical thinking and reasoning takes a lot of cognitive time and resources. It’s arguably the most complex thing our brains do, and complexity means delay, like asking for an elaborate cocktail at a bar rather than a standard pint; you’re going to be queuing a lot longer if you go for the former.

In evolutionary terms, delay and demand aren’t helpful, as decisions in the wild are often life-and-death ones. So in order to navigate the world around us quickly and efficiently, our brains develop these mental models of the world. It’s sort of a running-simulation that helps us rapidly determine the appropriate course of action in any likely situation.

For instance, when you go to a new restaurant, you don’t need to have it explained that you sit down and order food and pay for it later, because the nature of restaurants is already part of your mental model. If you walk down the high street and someone walks past in their underwear, you experience surprise, because your mental model suggests this shouldn’t happen. But if you’re at the beach at the height of summer, you’re not surprised, because this is consistent with your mental model. All our memories and experiences contribute to maintaining this mental model, and it allows us to interact with our environment, without having to figure it out from scratch each time.

But there’s a catch; the human brain is extremely complex now, and is capable of a lot more than that of any other creature. It holds beliefs, fantasies, attitudes, and biases, which all feed into the mental model of the world, often via the effect they have on our memories.

For instance, we’re a very social species; we value the approval of others, and empathise with them strongly. We want to be liked and to feel good about ourselves. Numerous studies have shown that humans (with the exception of those experiencing cognitive or mood disorders) default to interpretations of events which construct the best representation of ourselves to the wider world. We’re egotistical by nature, essentially. This has many advantages; it motivates us, it stops us feeling worthless, it gives life more meaning.

However, this doesn’t mean that the egocentric interpretations of events are correct. Egocentrism infuses our memory systems. We might recall memories in a way that favours our sense of self-worth, and this interpretation inspires more positive emotional reactions in our underlying mental processes, so gains more weight and becomes the ‘dominant’ memory. Similarly, things we don’t like or that cause us discomfort are assigned a negative value. Jobs we don’t enjoy doing, people we don’t understand or like, even races and cultures that confuse and unsettle us; thanks to the negative emotions these things inspire in us our memory of them is tainted. Some evidence even suggests that a negative emotional association can affect our very perception. Heights do appear higher if you’re afraid of them, tiny spiders are perceived as tarantula-sized killers by an arachnophobe.

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"Some evidence even suggests that a negative emotional association can affect our perception. Heights do appear higher if you’re afraid of them, tiny spiders are perceived as tarantula-sized killers by an arachnophobe."

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There are many more biases and inaccurate interpretations that carry emotional weight and thus influence and distort our memories, as well as the mental model derived from those memories. This distortion, combined with the flexible, adaptable, biological nature of our memories, where recall of real events can be tweaked or adjusted in response to later experiences, means the gap between what we remember and what actually happened grows ever wider.

Not only our memories are influenced, our response to new events also changes. Events that challenge our mental model of the world can feel ‘wrong’, can cause uncertainty, and therefore be met with resistance by the brain; if you aren’t certain what’s going to happen, something dangerous that you are unprepared for could happen. This triggers the brains threat-detection systems to varying degrees, leading to stress and anxiety.

This is where ‘fake news’ can come in, and why it’s so powerful. Both the existence of fake news, where people who have existing suspicions and beliefs are told what they think is actually true (reinforcing their mental model of the world), and the accusation of fake news, where facts and claims that people don’t like are devalued and dismissed (again reinforcing their mental model of the world) stimulate people in just the right way to make them reject what’s real in favour of what they choose to be real. This influences our perception, our memory, and our very understanding of the world around us. It’s a lot harder to avoid than you might think.

It is important, though, to not get fake news and false memories too mixed up. One does not equal the other. You can witness some fake news, and have a real memory of doing so. The news was fake, your memory is not. I watched a lot of Star Trek as a child, but I don’t remember ever being a member of Starfleet.

However, they aren’t wholly separate either. The very first research into false memories was done by Professor Elizabeth Loftus (arguably the biggest name in the field), investigating supposedly “repressed” memories of sexual abuse dredged up in therapy sessions, where later analysis strongly suggests the horrifying events never happened, and were implanted (hopefully by accident) by a therapist using dubious approaches and leading questions. If they expect to find memories of abuse, they often use approaches that end up actually creating them. This is, to put it mildly, bad.

And this points to another link between false memories and fake news: the effect of authority, or apparent legitimacy. Humans are a very social species, but also a very hierarchical one; our awareness of our standing in society, and who’s above or below us, is deeply embedded in the brain. This has many consequences, one of which is that we tend to believe those we look up to, respect, or just consider credible, often more than we do our own observations. A vulnerable patient will often trust a therapist implicitly, young children regularly take their understanding from what their parents tell them, solicitors in the stressful environment of a courtroom can be very intimidating for a witness and police offers invoke an instant obedience in many. In all of these cases it has been shown that when the authority figure asks leading questions, or makes observations that challenge what the person originally believed happened, an individuals memory is effectively distorted. Misinformation (Fake news by another name) can lead to false memories, if the source is deemed trustworthy.

And so it is with newspapers and other media platforms. Many people still believe that if something is printed or broadcast then it must have legitimacy, for all that’s increasingly not the case these days. We build our understanding of the world we cannot directly observe from reports and news. We expect these things to be accurate and honest. But all too frequently, that trust is not validated. Media outlets increasingly tell potential viewers and readers what they think they want to hear, or what the editor or owner thinks they should hear, and this will alter their understanding of the wider world. If you’re already suspicious of Muslims, and you live in Birmingham, and you’re told by your favoured paper that there are ‘no go’ Muslim areas of Birmingham, you may well remember encountering such a place on your travels. Despite never having done so.

And so it can occur, that fake news and the flexibility of the human brain and memory can coincide, to encourage people to believe things about the world that aren’t true, for the benefit of people who wish the world was other than it is.

Of course, it need not always be so malicious. Sometimes it’s just a matter of someone you trust more than yourself telling you things that you don’t recall but that are consistent with what you think or suspect. The brain is constantly filling in the gaps in our perception and understanding of the world. It should be no surprise to know that it does this with memory too.

Dean Burnett's second book, The Happy Brain (Faber and Faber) is released on May 3rd 2018.