Here’s why memories come flooding back when you visit places from your past



A lifetime of memories… but not always readily accessible.
Modus Vivendi/Shutterstock

Adam Osth, University of Melbourne

We all know our memories get worse as time goes on – your recollection of what you did yesterday is probably a lot better than for the same day three years ago.

And yet we often have moments where old and seemingly forgotten memories pop back into mind. Perhaps you have visited your childhood home, walked into your old bedroom, and been hit with a wave of nostalgia. What triggers this rush of memories, and how can you suddenly remember things you may not have thought about for decades?

Researchers are realising that the context in which memories are created is crucially important in remembering them later. This idea is known as “contextual-binding theory”, and it boils down to three components: context learning, context change, and memory search.




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Studying for exams? Here’s how to make your memory work for you


Let’s start with learning. It is well established that learning in the brain happens by a process of association. If A and B occur together, they become associated. Contextual-binding theory goes a step further: A and B are associated not just with one other, but also with the context in which they occurred.

What is context? It’s not just your physical location – it’s a mental state that also comprises the thoughts, emotions, and other mental activity you’re experiencing at a given moment. Even as you read this page, changes in your thoughts and mental activity are causing your mental context to change.

As a consequence, each memory is associated with different states of context. However, some context states will be similar to each other – perhaps because they share the same location, or mood, or have some other factor in common.

This similarity between contexts is important when it comes to retrieving memories. Your brain’s memory search process is rather like a Google search, in that you’re more likely to find what you’re looking for if your search terms closely match the source content. During memory search, your current mental context is your set of search terms. In any given situation, your brain is rapidly rifling through your memories for ones that most closely resemble your current state of context.

Simple but deep

These mechanisms are simple, but the implications are profound. According to the theory, you’re most likely to remember memories from contexts that are similar to the context you’re in now. Because your mental context is always changing, your mental context will be most similar to recently experienced memories. This explains why it’s harder to remember older events.

But, of course, older memories aren’t permanently forgotten. If you can change your context to resemble those from seemingly long-forgotten memories, you should be able to remember them. This is why those old memories come flooding back when you step into your childhood bedroom or walk past your old school.

The happiest days of your life, right?
Giedre Vaitekuna/Shutterstock

Context-dependent memory was confirmed by an ingenious 1975 experiment in which divers memorised lists of words and were then tested both on land and underwater. On land, their recall was best for the words they had learned on land, whereas underwater they were better at remembering the word lists they learned underwater.

This phenomenon isn’t limited to physical locations. You may have noticed that when you’re sad about something, you tend to remember other sad events from your life. This is because your mood and emotions also comprise your mental context. Experiments have confirmed that memory is enhanced when your current mood matches the mood in which you learned the information.

More than a century’s worth of studies have confirmed we are also better at remembering things if we experience them at different times, rather than repeatedly in quick session. This is one of the main reasons why, when preparing for exams, a regular study routine is more effective than cramming.

According to the theory, rapidly repeated material is associated with a single state of context, whereas material repeated across different times and events is associated with several different states of context. This pays off later, when you’re sitting in the exam hall desperately trying to recall the chemical formula for potassium permanganate, because your current state of context will be more likely to match one of the many states of context in which you so diligently did your chemistry revision.




Read more:
How memories are formed and retrieved by the brain revealed in a new study


Context in the brain

Contextual-binding theory can potentially explain a host of other phenomena, such as the effects of brain damage on memory. People with damage to a region in the centre of the brain called the hippocampus are often unable to form new memories. We suspect this is where context-binding actually occurs, especially given that the hippocampus receives inputs from virtually all other brain regions, enabling associations between different sights, smells, physical sensations, and emotions.

A competing theory, known as systems consolidation theory, instead proposes that memories are initially stored in the hippocampus but are gradually transferred and strengthened in other brain regions over time.

This theory is supported by the fact that memory for new material is better when you rest after learning. Time spent resting may give the brain a chance to consolidate new memories.

All part of the process.
Fizkes/Shutterstock

However, contextual-binding theory can also potentially explain this benefit. Resting immediately after learning, as opposed to carrying on shovelling facts into your brain, means fewer memories share the same context, making them easier to distinguish when you revisit that context later.

This also explains why rest is also beneficial before learning, as well as after. And it underpins the tried and tested advice for hardworking students everywhere: don’t forget to get lots of sleep!The Conversation

Adam Osth, Senior Lecturer, University of Melbourne

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Comments


Due to the increased volume of spam posts and propaganda from other websites (including those of a ‘Christian’ nature who think it is acceptable practice to spam others) I am attempting to tighten up the protocols for comments on this Blog. I don’t want to stop comments altogether, but sadly, that may eventually happen. It seems there are some idiots (I am being kind) who want to continue to attempt to post their propaganda and nonsense on this Blog via the comments, even though they never get through the moderation process. I am fed up with having to work through all of this rubbish (and that is generally what it is). I understand there are some genuine people out there that will be inconvenienced by this ‘tightening’ up in the comments process here and I really didn’t want you to have to endure this moving forward. I am saddened that this has had to happen.

Limited Posts During Personal Maintenance Time (Annual Leave/Holidays)


It’s that time of year when I take some time off for a variety of reasons and tasks – in short, it’s annual leave time. Yes, some much appreciated time off work. Last year I attempted a holiday and nearly died – diseased kidneys, blood poisoning, and internal bleeding – all a result of a kidney stone. What followed was months of illness, as that experience proved a catalyst for an old illness to make a renewed appearance also (Chronic Fatigue Syndrome – CFS). Finally, in the last few weeks, I have been reasonably well and have been working at a frantic pace, trying to make up for lost time.

So now I hope to enjoy these next few weeks, do some traveling (including to the previous destination that I never arrived at due to falling ill on the way), get a bit of personal things done (yeah, including a host of medical stuff) and really, just to relax and have a break – an enjoyable break in fact.

So what does this mean for the Blogs? Well, I was going to continue to post in a haphazard manner over the next three weeks, but have since thought better of it and will not do so. So no new posts for the next three weeks – there may be some still to appear on one of the Blogs that I scheduled in advance, but you won’t hear much from me during this period. So enjoy the break from me, as I enjoy the break from everyday usual life.

No Posts This Week


I have been battling poor health now for months and I have reached the point of peak exhaustion (if that is a thing). I’ll be taking extended leave during May, along with a lengthy break from the Blogs, with the aim being that of taking the opportunity to recover and recharge the batteries. However, I also need an immediate break and so will not be posting to any of my Blogs this week. I have to try and get through work through April, in order to get through to May and my extended break. This may prove to be a very difficult task and even perhaps prove unattainable, yet that is the goal. Each day closer makes the remaining time that little bit easier to contend with. So, in short, there will be no posts for the remainder of this week and I will then start to bring the Blogs back ‘online’ again after that – at least until my extended break in May.

Silly Season Break


Just a quick post to let everyone know that this Blog will be on a break from now, over the silly season and should return early in the New Year. This isn’t so much because of Christmas and the New Year directly, but because my work schedule is so great and I won’t have the time to put in on the Blog during this period. I would have liked to keep up the posts, but it has become clear I just can’t keep it up at the moment – it is far too busy at work and with increasing staff shortages over the next couple of weeks, it will not get any easier.

Let me also take the opportunity to wish you all a happy and safe Christmas, and New Year period. Enjoy this time with family and friends.

More Time Away


I was posting a few Blogs and getting a few more ready when some bad news came through. Sadly I will be needing to take some more time away from the Blogs (immediately) – which is something completely unplanned and unexpected. This may be a lengthy break of two to three weeks. I’m afraid this is unavoidable and apologise for the time away from the Blog.

System Restored


I am very thankful. Having battled away for the past 48 hours trying to salvage files, I have now also been able to get into the system restore feature on my computer, attempt to restore the system and… it worked. Very thankful. It is working again.

I now need to bring the various Blogs back online and to start posting again.