We tend to think of our memories as impressions of the past that remain fully intact, preserved somewhere inside our brains. In fact, we construct and reconstruct our memories every time we attempt to recall them. Memory Lane introduces readers to the cutting-edge science of human memory, revealing how our recollections of the past are constantly adapting and changing, and why a faulty memory isnât always a bad thing.
Whatâs the main idea that you want to get across with this book?
Our goals for Memory Lane were twofold. First, we wanted to talk about the fragility of memory, and the fact that we often have unrealistic expectations of what our memories can (or should) do. In the book, we describe how our memories can be distorted by new information as well as by our pre-existing beliefs and prejudices, and we consider some of the implications of this in legal and personal settings. Second, we wanted to counter this impression of âdoom and gloomâ by explaining why our memories evolved this way. We give lots of examples of how our âflawedâ memories help us survive and thrive.
One surprising idea in your book is that forgetting can actually be a good thing. Why is that?
Most of us tend to think of forgetting as a bad thing that interferes with our daily activities. We might even see it as a sign that there is something wrong with our memories. Forgetting can often be frustrating, such as when we canât bring someoneâs name to mind or donât remember to go to the post office, but itâs also a really important part of our memory systems. Forgetting allows our memories to be more efficient, by filtering out all the mundane details of our lives and allowing us to remember the most important parts. Just as a computer algorithm might compress a photograph by recognising that all the blue pixels that make up the sky are the same as each other, we can recognise the commonalties among our day-to-day experiences. For example, you probably eat more or less the same thing for breakfast every day. It would be a very inefficient use of resources for you to store a high definition memory of every single breakfast you have ever eaten, including the precise shade and crunch of every cornflake, temperature of the milk, your exact hunger levels etc. Instead, your memory will typically extract the gist of these events (âI usually eat cornflakes for breakfastâ) and use that as a template for storing future similar memories. This might mean that you forget some of the details, but it leaves you with the mental bandwidth to focus on more important things.
Is it true that forgetting can actually make us happier?
In Jane Austenâs Pride and Prejudice, Elizabeth Bennetâs sister Jane is shocked that Lizzy intends to marry Mr Darcy when she has always disliked him. Tongue firmly in cheek, Lizzy tells Jane that âin such cases as these, a good memory is unpardonable.â Lizzy is joking, but in fact there is plenty of evidence that a selective memory is good for our mental health and our relationships. We often think that having a perfect memory would be a real advantage in our lives, but in fact people who do have exceptionally good memories for their lives â those with the rare condition of âhighly superior autobiographical memoryâ or âhyperthymesiaâ â often report struggling to get over events from their past. For most of us, time is a great healer, but for those with HSAM every teenage heartbreak remains just as vivid after many years as it was the day it happened. It is the ability to let past hurts, embarrassments and disappointments fade with time that allows us to move on with our lives and protect our mental wellbeing.
You use the metaphor of a Lego tower to describe memory. Can you explain that?
The Lego tower metaphor is used to demonstrate the fact that human memory is reconstructive. What that means is that when we remember something, we arenât really retrieving that memory fully-formed from some storage archive in the brain; instead, we are reconstructing the memory, piece by piece. The key idea here is that memory is an active process: we arenât passively accessing our memories, we are actively creating them. We tend to use mental âblueprintsâ of past experiences to help us construct memories of a given event. Sometimes this can mean that our memories will be biased by those previous experiences, and shaped by our preconceptions, beliefs and prejudices. We will also tend to construct our memories in such a way that they reflect well on us - for example, we tend to remember that we have been kinder and more generous in the past than we really were!
One very common consequence of the reconstructive nature of memory is our tendency to incorporate new information into memories of past events. You can think of this as like someone handing you a new brick that wasnât in your original Lego tower, but that gets added in when you rebuild the tower and retrieve the memory. We see this very clearly in the case of eyewitnesses, who frequently come to misremember details of a crime they witnessed when someone else (such as a police officer, a lawyer in court, or another witness) describes or alludes to a detail that wasnât present in the original scene. In this way, people can come to remember that a traffic light was red instead of green, that a thief had long hair instead of short or that actions happened in a different order to what was originally witnessed.
In the book you give lots of examples of really flawed memories, including people misidentifying the perpetrators of crimes or even remembering entire events that never happened. Why did our memories evolve this way?
It can be hard to understand why our memories would have evolved to be so flawed. Surely, if memory is good for anything it should be to provide an accurate record of our lives? Itâs helpful to think here about what memory is for. From an evolutionary perspective, traits that survive natural selection do so because they offer some benefit to survival or reproduction. We donât need our memories to provide a verbatim record of every conversation we have ever had; instead, we need them to inform us about survival-relevant situations, giving us information as to whether a particular person is trustworthy or is likely to harm us, whether a food is safe to eat, or whether a potential course of action ended well for us in the past.
The reconstructive nature of memory supports us in making these decisions, and most of the time it does just what we need it to do. We already know that we can bring detailed recollections of past events into our mindsâ eye, filling in the blanks in our memories with information from similar past events. A closely related function is the ability to vividly imagine hypothetical situations, that range from the drably mundane (âwill I make my train if I leave just after 5pm?â) to the brilliantly fantastical (âwhat would a world where everyone can fly be like?â) This capacity to imagine is central to our ability to reconstruct memories and âfill in the gapsâ with what likely happened. This is mostly a very helpful process, allowing to us to maintain a coherent sense of ourselves and the narrative of our lives. Sometimes though, this ability can lead us astray and cause us to construct memories of events that didnât happen at all.
How does technology interact with our memory?
This is a great question! We are often asked whether our memories are being âdestroyedâ by technology in some way. The answer to that is ânoâ â but technology does interact with our memories in lots of interesting ways, many of which arenât specific to technology at all. For example, there is good evidence that when you take a photo, your memory of the event is less detailed than if you had not taken the photo. Similarly, when people use SatNav tools to navigate around a city, they end up with less accurate memories of the route they took. This is a process called âcognitive offloadingâ, where we essentially hand off the job of remembering some details to a technological agent (in this case, the camera or the SatNav) instead of committing those details to memory ourselves. This is totally normal, and is in fact the same process as jotting down a phone number on a piece of paper so you donât have to remember it yourself. Itâs just taking advantage of the tools available to us so we can use our cognitive resources more efficiently. However, there are some things to be aware of when we rely on technology to take the place of our memories. In the book, we talk about the use of body-worn cameras by police officers as an example of this. These cameras can be a really useful tool for supplementing the deficits of human memory, but we need to be very careful about how and when their evidence is used. The camera sees both more than a human observer (because it might capture details we miss) but also less, as the camera cannot capture details the observer sees in their peripheral vision or when they turn their heads. Viewing this footage can change an officerâs memory of how they felt and what they saw in the moment, with potential consequences in legal settings.
How did you find the process of writing a popular science book?
Maybe this is unusual for authors to say, but we found the process surprisingly easy and very enjoyable! We work together a lot and have done for many years. Having an established, trusted partnership is invaluable when it comes to writing a book. We were also writing about a topic squarely within our expertise, a topic we research and teach about in our day jobs as Associate Professors, so the writing process was particularly smooth. We wrote the whole book in less than six months and are really happy with how it turned out.
What final message would you like readers to take from this book?
Be kind to yourself and to others. Give yourself some grace for your memory lapses â after all, youâre only human! At the same time, extend that same courtesy to others, and recognise that our memories are constantly changing and updating to reflect our experiences. At the end of the day, itâs important to remember that we are actively writing the book of our lives, not just passively reading it!
About the Authors
Ciara Greene is associate professor in the School of Psychology at University College Dublin, where she leads the Attention and Memory Laboratory. Gillian Murphy is associate professor in the School of Applied Psychology at University College Cork and a funded investigator at Lero, the Science Foundation Ireland Research Centre for Software.