Remembering and Forgetting: Why our Memories are Fallible.

 How Memories Are Stored

It was midnight when Bernice got off work. She was exhausted after a long and terrible day and just wanted to get home to a hot bath. She was driving down the street, flipping through radio stations when she pulled up to a stop sign and saw something weird. A shadowy figure ran up to an idling fruit truck, pushed the delivery man down, grabbed a crate of bananas, and ran off around the corner. Bernice was pretty shaken up, but she made sure the driver was okay, and then she called the police, describing the thief as a pale, lanky man wearing a dark jacket and a baseball cap. She gave the cops her information, and then she went home. A couple of days later, the police asked her to come down to the station to identify a potential thief, a guy who more or less matched her description and was found eating a banana early that morning, near the scene of the crime. 

Although the guy professed innocence, Bernice said it was him, and they locked him up. But at the trial, the defense called a memory expert to the stand, and soon after that, the suspect walked. Today's lesson may not make you an expert worthy of the witness stand, but by the time we're done, you'll understand a lot more about how we retrieve memories we think we've stored and why the accused banana thief was set free. We're all constantly retrieving memories throughout the day. You're remembering where you parked your car, or if you fed the cat or called your mom because it's a birthday. You'll remember from last week that while our implicit memories, like how to talk and ride a bike, are dealt with on a mostly automatic and non-conscious level, our explicit memories, the chronicles of our personal experiences and general knowledge, often require conscious effortful work. Her niece had to notice, encode, store, and later consciously retrieve details about the crime she witnessed. 

MEMORY RETRIEVAL CUES

What color was the guy's jacket? What did he look like? What did he steal? And where did he run? It takes a lot of work to retrieve memories from long-term storage, and the truth is, a lot can go wrong along the way. To understand all of the many fascinating ways you forget things, we need to talk more about how you remember them. Our memories are not like books in the library of your mind. You don't just pluck a neatly packaged memory right off the shelf about where you left your phone or the hair color of a fruit thief. Instead, your memories are more like the spider webs in the dank catacombs of your mind, a series of interconnected associations that link all sorts of diverse things as bits of information get stuck to other bits of information. 

Maybe Bernice remembers that the night of the crime was chilly with a full moon that Beyoncé was on the radio, and the fruit truck had plates from California, which is where her grandfather lives. All those bits of information in the web of memory, the weather, the song, the plates, can serve as retrieval cues. kind of like a trail of breadcrumbs leading back to a particular memory. The more retrieval cues you inadvertently or intentionally build along the way, the better you can backtrack and find the memory you're looking for. This way of activating associations non-consciously is called priming, sometimes called memoryless memory. It's how invisible memories that you didn't know you had can awaken old associations. Priming is often how you jog your memory. 

This kind of recall is sometimes referred to as context-dependent memory. Say you're reading in bed, and you want to underline a quote but you don't have a pen. Well, you get up and you go to the other room to find your special light-up Hello Kitty pen, but you get distracted and suddenly you find yourself in the kitchen. You're like, why? Why, mind? Why am I in the kitchen? What is here? Why am I... There was a re... And I don't know, but I'm here now, and... It's only when you retrace your steps and return to bed to the initial context where you read that quote and encoded that first thought of wanting that pen that the memory comes back. And then you're like, oh, I need to go get the pen. 

Huh. If some memories are context-dependent, others are state-dependent, and also mood-congruent. This just means that our states and our emotions can also serve as retrieval cues. If I had a throbbing headache and a super bad day, I'm more likely to start recalling bad memories, because I'm priming negative associations. But of course, if I'm relaxed and jolly, I'm prone to remember happy times and prolonging my good mood. Another funny memory retrieval quirk speaks not to our location or emotions, but to the order in which we receive new information. So, say you make a grocery list in the morning, but a few hours later, you're at the store, you realize you left it at home. You'd be more likely to recall the first items on the list, bananas and bread, and the last items, pickles and cheese, than anything in the middle. 

This is known as the serial position effect. This might be because the early words benefited from what's known as the primacy effect, and made it into your long-term memory because they were rehearsed more. Meanwhile, the last words lingered in the working memory, through the recency effect. But those poor middle words, they didn't benefit from either effect and therefore escaped your brain, which is why you now have no toilet paper, dog food, toothpaste, or cookies. Who forgets cookies? But even with all these tricks and associations, things still go wrong, memory can fail or become distorted, and of course we forget things. Forgetfulness can be as minor as those frustrating moments where you're like, ah, it's on the tip of my tongue, it's the guy, the guy's got a hair and a face, and like, 

shoulders, or as major as Clive Waring, whose neurological damage made it impossible for him to recall the past or create new memories. Of course, we all forget things, and typically we do it in one of three different ways. We fail to encode it, we fail to retrieve it, or we experience what psychologists call storage decay. Sometimes forgetting something just means it never really got through your encoding process in the first place. I mean, think of all the stuff that's going on around you at any given moment. We only actually notice a fraction of what we sense, and we can only consciously hold so many bits of information in our minds at any given time, so what we fail to notice, we tend to not encode, and thus don't remember. 

Bernice noticed a dark jacket, Beyonce, and bananas, but she didn't encode much about the driver or the color of the thief's shoes. Then again, even memories that have been encoded are still vulnerable to storage decay, or natural forgetting over time. Interestingly, even though we can forget things pretty quickly, the amount of data that we forget can actually level off after a while. This means that Bernice would have forgotten about half of what she first noticed at the crime scene a couple days later. But what she still remembered, she'd likely hang on to, because the rate at which we forget tends to plateau. A lot of times, forgetting doesn't mean our memory just fades to black. it means we can't call it up on demand because of retrieval failure. 

How Information is Forgettten

We all know the common tip-of-the-tongue phenomenon, where you feel like you know the name of that weird-looking, hard-backed animal that rolls up into a ball. It's kind of cute and weird, and I think it gets leprosy or something, but what is it? That's where retrieval cues can come in handy. If I say to you, it starts with the letter A, suddenly, armadillo! Sometimes these retrieval problems stem from interference from other memories getting in the way. Essentially, cluttering the brain. Sometimes old stuff that you've learned keeps you from recalling new stuff, like if you change one of your passwords but keep recalling an old one every time you want to log in. That's called proactive, or forward-acting interference. The flip side of that is retroactive, or backward-acting interference, which happens when new learning gets in the way of recalling old information. 

Like if you start studying Spanish, it may interfere with the French that you've already learned. There's a lot of reconstruction and inferring involved when you try to flesh out a memory, and every time you replay it in your mind or relate it to a friend, it changes. Just a little. So, in a way, we're all sort of perpetually rewriting our pasts. While this is an inevitable part of human nature, it can prove dangerous at times. Misleading information can get incorporated into a memory and twist the truth, and yes, there's an effect for this. It's called the misinformation effect. American psychologist and memory expert Elizabeth Loftus has spent decades showing how eyewitnesses inadvertently tweak and reconstruct their memories after accidents or crimes. In one experiment, two groups watched a film of a car accident. 

Those asked how fast the cars were going when they smashed into each other estimated much higher speeds than those who were asked about the cars hitting each other. Smash is the leading word that essentially altered the witnesses' memories, so much so that a week later when both groups were asked if they saw any broken glass, those who heard the word smash were twice as likely to report seeing bits of glass when, in fact, the original film didn't show any. In Bernice's case, chances are her memory of the robbery would be altered if the prosecution said the thief assaulted rather than pushed the driver. This sort of interfering or misleading information may also manifest itself as source misattribution, like when you forget or misrecall the source of a memory. 

ISSUES WITH EYEWITNESS ACCOUNT

In the case of Bernice, when she saw the suspect in the courtroom, she thought she recognized him from the night of the crime when in reality, He just served a coffee earlier that day. But her memory of the event had probably already been tweaked several times before she even made it into the courtroom. Like, she relived the tale multiple times in her own mind in which she told other people about it, and every time she introduced errors, filled in memory gaps with reasonable guesses. Not only that, but we know Bernice was already tired and stressed when she witnessed the event, and we know our emotions can influence whether we remember or whether we forget. Because memory is both a reconstruction and a reproduction of past events, 

We can't ever really be sure if a memory is real just because it feels real. Elizabeth Loftus knows this. She's frequently called in to testify against the accuracy of eyewitnesses. In fact, of all the U.S. prisoners who have been exonerated based on DNA evidence presented by the Innocence Project, a nonprofit legal group, 75% of them were convicted by mistaken eyewitnesses. That is a lot of innocent people. Bernice meant well, of course. She's an honest lady. But all those factors, the emotion, the retelling, the suggestions of outside sources, combined with the darkness, the quick glimpse, the passing of time, and maybe even Beyonce, ended up leading to a mistake in the thief's identification. Turns out, that human memory is actually a very fragile thing. 

We're all largely the product of the stories that we tell ourselves. If you haven't forgotten already, today, You learned about how our memories are stored in webs of association, aided by retrieval cues and priming and influenced by context and mood. You also learned how we forget information, how our memories are susceptible to interference and misinformation, and why eyewitnesses are often not as reliable as you might think.