Category: Memory

Neuroscientists reveal how the brain stores memories and information and which part of the brain stores memories.

Imagine you had a tiny device inside your brain that could ‘see’ the moment a new memory was formed.

What would it record?

Since the brain is made up of neurons linked together in a vast network, it seems reasonable to suppose that some part of that network would activate when you, say, saw your first child being born.

But how big a network?

Is that memory contained in a handful of neurons or is it distributed widely across the network?

Fascinating clues come from a study of nine patients who had had electrodes implanted in their brains to help monitor their seizures (Wixted et al., 2014).

These electrodes can monitor the activity of single neurons in the brain.

With their permission, neuroscientists took advantage of this window into the electrical activity of the brain to examine how memories are laid down and recalled.

How does the brain store memories?

For the test, participants simply learned a series of words, then were presented with another list which contained some words they’d learned along with some new ones.

They were asked to say which ones they’d seen before.

The results amazed the study’s first author John T. Wixted:

“Intuitively, one might expect to find that any neuron that responds to one item from the list would also respond to the other items from the list, but our results did not look anything like that.

The amazing thing about these counterintuitive findings is that they could not be more in line with what influential neurocomputational theorists long ago predicted must be true.”

Part of the brain where memories are stored

As expected, the memory was encoded in the hippocampus, an area of the brain that is vital for memory.

What they saw was that the memory for a single word was encoded across hundreds of thousands of neurons in a distributed network.

While this may sound like a lot, it’s actually only a small fraction: the number of neurons firing in response to a single word was about 2 percent of those in the hippocampus.

So, if you could look inside your own brain when a new memory is formed, what you’d see is that a relatively small network of neurons in the hippocampus jumps into action.

When you recall a memory, that same network leaps into action again.

The study’s authors explain:

“[This is]…a sparse distributed coding scheme in which each memory is coded by the activity of a small proportion of hippocampal neurons, and each neuron contributes to the representation of only a few memories.” (Wixted et al., 2014).

The most efficient way to store memories

Some have theorised that this is the most efficient way for the brain to work because:

• If memories were localised to individual neurons then they could easily be lost if those particular neurons died.
• If memories were too widely spread across the network, memories would be too easily overwritten or confused.

One of the study’s authors, Dr. Peter N. Steinmetz commented:

“To really understand how the brain represents memory, we must understand how memory is represented by the fundamental computational units of the brain — single neurons — and their networks.

“Knowing the mechanism of memory storage and retrieval is a critical step in understanding how to better treat the dementing illnesses affecting our growing elderly population.”

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Stress affects memory negatively through the action of cortisol, the stress hormone.

A link between the stress hormone cortisol and short-term memory problems has been found by research.

Although cortisol is a natural hormone that spikes when we are stressed to help us deal with challenging situations, over time its long-term effects may be detrimental to short-term memory.

This is the first study to link long-term exposure to cortisol with short-term memory problems.

The study, conducted by researchers at the University of Iowa and published in the Journal of Neuroscience, found that high levels of cortisol were associated with a loss of synapses in the prefrontal cortex, a structure that’s important for short-term memory (Anderson et al., 2014).

Study of how stress affects memory

The findings are based on a study of rats which were 21 months old — this meant their brains were roughly equivalent to that of a 65-year-old human.

In the study, rats’ corticosterone levels were measured.

They were then given a T-shaped maze to run through which required them to remember which direction the treats were.

Some of the rats forgot which direction to turn after a short delay — just as human short-term memory decays over a few minutes — but those with higher levels of corticosterone were more likely to forget.

Rats with low levels of corticosterone got the direction right 80% of the time, while those with high levels of corticosterone only got it right 58 percent of the time.

When their brains were examined, it turned out that the stressed and forgetful rats had 20 percent fewer synapses in their prefrontal cortex, suggesting this was the cause of the short-term memory loss.

When the older rats were compared with younger ones, the older ones with low levels of the stress hormone performed just as well as the younger ones.

The same could not be said of those with higher levels of the stress hormone.

This study may help to explain why some people’s memory declines so dramatically with age, while others remains relatively unaffected.

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Eyewitness to a crime remembered twice as many details using this technique that can jog your memory.

Closing your eyes really can help jog the memory, a study finds.

The results should be useful for helping eyewitnesses to crimes remember more details when questioned by police.

The study, published in the journal Legal and Criminological Psychology, had participants watching an electrician entering a property, doing some work and stealing various items (Nash et al., 2015).

Afterwards, some were asked questions with their eyes open and others with their eyes closed.

The psychologists were also interested to see if building rapport before asking the questions made any difference.

Memory jogged

The results revealed that closing the eyes gave the biggest boost to recall, but establishing some rapport before questioning was also beneficial.

People who had their eyes open and did not have some rapport with questioner only got 41 percent of the questions right.

People with their eyes closed and who had some rapport got 75 percent of the questions right.

Dr Robert Nash, who led the study, said:

“It is clear from our research that closing the eyes and building rapport help with witness recall.

Although closing your eyes to remember seems to work whether or not rapport has been built beforehand, our results show that building rapport makes witnesses more at ease with closing their eyes.

That in itself is vital if we are to encourage witnesses to use this helpful technique during interviews.”

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Improve your memory, concentration, power and retention by using these 14 science-backed techniques to increase cognitive function.

Many of the usual methods for how to improve memory are well-known, such as using imagery, chunking and the forbidding sounding ‘brain training’.

The problem with most of these methods is they involve a fair amount of mental effort.

So, here are 14 mostly easy ways to improve memory that are backed up by psychological research, many requiring relatively little effort.

Few of these methods for how to improve memory require you to train hard, spend any money or take illegal drugs.

All free, all pretty easy, all natural!

1. A good mood improves memory

Something as simple as getting a bag of candy is enough to improve memory and concentration, research finds.

In fact, anything that quickly puts you in a good mood can improve memory and decision-making.

Professor Ellen Peters, who co-authored the study, said:

“There has been lots of research showing that younger adults are more creative and cognitively flexible when they are in a good mood.

But because of the cognitive declines that come with aging, we weren’t sure that a good mood would be able to help older adults.

So these results are good news.”

2. 40 seconds rehearsal boosts memory

Rehearsing a memory for just 40 seconds could be the key to permanent recall, a study finds.

When rehearsing a memory, the same area of the brain is activated as when laying it down, psychologists found.

Dr Chris Bird, who led the research, said:

“We know that recent memories are susceptible to being lost until a period of consolidation has elapsed.

In this study we have shown that a brief period of rehearsal has a huge effect on our ability to remember complex, lifelike events over periods of 1-2 weeks.

3. Associations improve memory

‘Reminders by association’ are a great tool to help improve memory for something in the future, research demonstrates.

Here are a few examples of ‘reminders by association’:

• A picture of your family by your desk reminds you to call them and tell them you will be late home.
• A piece of litter on the floor reminds you to put the bins out.

Little environmental cues like this were enough to double the number of people who remembered to perform some future action.

4. The aroma of rosemary improves memory

The aroma of rosemary essential oil can improve memory, concentration and the ability to remember future events, research finds.

For the study 66 people took various memory tests either in a room that was scented with rosemary or without.

Those breathing the scent of rosemary performed better.

5. How to improve memory: write about your problems

To do complex tasks we rely on our ‘working memory’.

This is our ability to shuttle information in and out of consciousness and manipulate it.

A more efficient working memory contributes to better learning, planning, reasoning and concentration.

One way to improve working memory capacity indirectly is through expressive writing.

You sit down for 20 minutes a few times a month and write about something traumatic that has happened to you.

Yogo and Fujihara (2008) found that it improved working memory after 5 weeks.

Psychologists aren’t exactly sure why this works, but it does have a measurable effect.

6. Vegetables linked to better memory

Eating vegetables — but not fruit — helps improve memory, research finds.

The study of 3,718 people over 65 living in Chicago asked how often people ate particular foods and administered cognitive tests.

Professor Martha Clare Morris, who led the study, explained the results:

“Compared to people who consumed less than one serving of vegetables a day, people who ate at least 2.8 servings of vegetables a day saw their rate of cognitive change slow by roughly 40 percent.

This decrease is equivalent to about 5 years of younger age.”

Green leafy vegetables showed the strongest association with an improved memory — they are also likely to help concentration.

Older people in the study got the greatest benefit from eating more vegetables.

7. Natural scenes improve memory

Nature has a magical effect on us.

It’s something we’ve always known, but psychologists are only just getting around to measuring it.

One of nature’s beneficial effects an easy way for how to improve memory and concentration.

In one study people who walked around an arboretum did 20 percent better on a memory test than those who went for a walk around busy streets.

In fact you don’t even need to leave the house.

Although the effects aren’t as powerful, you can just look at pictures of nature and that also has a beneficial effect (I describe this study in detail here).

8. Say words aloud to improve memory

This is surely the easiest of all method for how to improve memory: if you want to remember something in particular from a load of other things, just say it out loud.

A study (described here) found memory improvements of 10 percent for words said out loud, or even just mouthed: a relatively small gain, but at a tiny cost.

9. Drink hot chocolate

Two cups of hot chocolate a day could help keep the brain healthy, a study finds.

The research involved 60 people whose average age was 73.

They were given tests of memory, concentration, thinking skills and the blood flow in their brains was measured.

People who had impaired blood flow in the brain improved after drinking the flavanol-rich cocoa.

10. Meditation improves memory and concentration

Meditation has been consistently found to improve cognitive functioning, including memory.

But meditation takes time doesn’t it?

Long, hard hours of practice?

Well, maybe not.

In one recent study, participants who meditated for 4 sessions of only 20 minutes, once a day, were able to improve memory, concentration and brain function (the study is described here, also see my beginner’s guide to mindfulness meditation).

11. Exercise improves memory

Long-term memory is improved by exercise four hours after learning, a study finds.

Exercising directly after learning, though, does not improve memory at all.

In addition, brain scans revealed that exercise lead to more precise representations of memories in the hippocampus.

The scientists are not sure yet why exercise after learning improves memory.

However, they write:

“Considering that the exercise intervention took place after learning, delayed exercise most likely affected memory retention through an impact on memory consolidation.”

12. Predict your memory performance

Simply asking ourselves whether or not we’ll remember something is an unusual method for how to improve memory.

This works for both recalling things that have happened in the past and trying to remember to do things in the future.

When Meier et al., (2011) tested people’s prospective memory (remembering to do something in the future), they found that trying to predict performance improves memory.

On some tasks people’s performance increased by almost 50 percent.

13. Use your body to improve memory encoding

We don’t just think with our minds, we also use our bodies.

For example, research has shown that we understand language better if it’s accompanied by gestures.

We can also use gestures to encode memories.

Researchers trying to teach Japanese verbs to English speakers found that gesturing while learning helped improve memory (Kelly et al., 2009).

Participants who used hand gestures which suggested the word were able to recall almost twice as many Japanese words a week later.

14. Use your body to improve memory recall

Since our bodies are important in encoding a memory, they can also help improve memory recall.

Psychologists have found that we recall past episodes better when we are in the same mood or our body is in the same position (Dijkstra et al., 2007).

This works to a remarkably abstract degree.

In one study by Cassasanto and Dijkstra (2010), participants were better able to retrieve positive memories when they moved marbles upwards and negative memories when they moved marbles downwards.

This seems to be because we associate up with happy and down with sad.

Exercise and memory training

If all these methods seem a bit lazy, then you can always put in a bit more effort.

Probably the best way of improving your overall cognitive health is exercise.

Studies regularly find that increasing aerobic fitness is particularly good for executive function and working memory (check out this previous article on which cognitive enhancers work).

Conversely, stay in bed all the time and your working memory gets worse (Lipnicki et al., 2009).

Take your memory training to the limit and an incredible study by Ericsson et al. (1980) shows what can be achieved.

Our typical short-term memory span is about 7 things.

In other words we can hold around seven things in mind at the same time.

These researchers, though, increased one person’s memory span to 79 digits after 230 hours of practice, mostly using mnemonic systems.

Shows what you can do if you put in the hours.

That said, I’ll be sticking to a nice walk around the park.

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The misinformation effect in psychology refers to memories being changed after the event — as demonstrated by Loftus and Palmer (1974).

The misinformation effect in psychology is the tendency for people’s recall to get less accurate when they are given more information afterwards.

in other words, someone’s memories can be altered after the event by things that other people say or do.

This is particularly important in areas like eyewitness testimony, which could determine criminal guilt.

Imagine a witness is asked misleading questions which cause their memories of the event to be warped — someone’s life could hang in the balance.

The misinformation effect occurs because of two of the sins of memory: misattribution and suggestibility.

Real life example of a personal memory

The misinformation effect is also important in more mundane circumstances, such as people’s personal histories.

For example, I have a memory from when I was three years old of playing in a sandpit.

I don’t remember much else about it other than this sandpit was outside the building in which I lived.

For years I used to think this was my earliest memory, now I’m not so sure and here’s why.

Misinformation effect example

The work of Elizabeth Loftus, a renowned expert on human memory, has been extremely influential in this area as one of her early studies demonstrates.

Like some of the best experiments, although Loftus and Palmer’s (1974) study on the misinformation effect was quite simple, its implications were profound.

In the first of two experiments, 45 participants watched a film of a car accident.

Nine of these were then asked this specific question: “About how fast were the cars going when they hit each other?”.

The other four groups of nine were asked an almost identical question but with one important difference.

Instead of the word hit, the words ‘smashed’, ‘collided’, ‘bumped’, and ‘contacted’ were used.

The wording of question changed the answer

The participants who were asked the question using the word ‘smashed’ as opposed to ‘contacted’, estimated the cars were travelling, on average, almost 10mph faster.

The other words were fanned out in between.

So, what is this telling us?

Probably, that because people are not good at gauging the speed of a car, the cue comes from the experimenter.

If the experimenter asks the question using the word ‘smashed’, the participant assumes it was going faster than if they say ‘contacted’.

The misinformation effect after one week

It’s in the follow-up study that things get interesting.

The same experiment was repeated roughly as before, but with 150 participants.

This time, however, participants filled out a questionnaire about the crash and were then asked to return in a week.

As before, the question about the speed of the crash was varied between groups.

Some read ‘hit’, some ‘smashed’ and so on.

One week later participants returned and were asked to fill out a questionnaire about the accident in which was hidden a crucial question: “Did you see any broken glass?”.

As broken glass is indicative of a more serious accident, so greater speed, Loftus and Palmer expected the group in which the word ‘smashed’ had been used would be more likely to indicate there was broken glass.

This was exactly what they found.

What causes the misinformation effect

There are a number of different theories as to why the misinformation effect occurs.

• Misleading information may simply overwrite the original memory.
• The misleading information may be blended with the original memory to create a hybrid.
• The misinformation may simply be used to fill in the gap if there is no memory of the occurrence.
• The misinformation effect may be partly a recency effect: in other words because the information was inserted into memory more recently, it is easier to recall.

Factors influencing the misinformation effect

Several factors can influence the misinformation effect, which include:

• Personality: introverts may be particularly susceptible to the misinformation effect.
• Age: young children are also particularly susceptible to the misinformation effect.
• News reports: when people read news reports they naturally incorporate these into their memories of events they may or may not have witnessed.
• Discussing events with other witnesses: as people who have witnessed an even discuss it with each other, their memories can become distorted in this way.
• Time: when the misinformation is provided recently it tends to supersede older memories.
• Repeated exposure: The more times people are exposed to a piece of misinformation, the greater the misinformation effect.

Memories are malleable

Reporting their experiment Loftus and Palmer adopt a cautious tone as befits a journal article.

For them it is a replication of a fact already known.

That the phrasing of a question about an event can affect our memory for that event.

For me, although the experiment is deceptively simple, it goes to the heart of how memories are constructed.

It makes me wonder if that childhood sandpit in my mind’s eye is really something I can remember.

What about your childhood memories?

What about your memory for last week?

To what extent are things you remember happening a week ago affected by intervening events and people?

The beauty of Loftus and Palmer’s experiment is it shows how important other people can be in shaping our own memories.

Whether or not my memory is real or a construction isn’t so important in the context of that sandpit, but what if I’m an eyewitness to a serious crime, called to testify in court?

What if an adult ‘recovers’ a memory of being abused by their parents as a child?

The answers to these questions have vital impacts on the lives of all those involved.

Loftus’ later work has taken in both of these highly controversial questions, and more.

Still, my thoughts often return to this original study in more mundane, personal terms.

Do I really remember that sandpit?

I can see myself sitting there, playing, looking up past the building, into the sky.

If that memory is false, can I ever really remember anything true at all?

How to avoid the misinformation effect

A number of strategies have been suggested to fight the misinformation effect:

• Use questions: the misinformation effect can be combatted by asking questions and avoiding declarative statements.
• Corrections and warnings: the misinformation effect can be fought be reminders that misinformation may be included in information being presented.
• Self-awareness: being self-aware and having more confidence in one’s memory can combat the misinformation effect.

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The commitment and self-consistency bias refers to the idea that people assume less change in their attitudes and beliefs than really occurs.

The consistency bias, also known as the commitment bias, is believing one’s past and present attitudes are similar.

In other words, the consistency bias means we tend to think our attitudes and beliefs have changed less than they really have.

However, in reality, our attitudes, beliefs and behaviours change more than we guess.

Examples of the commitment and consistency bias

What were your political views a decade ago?

How good was your relationship last year?

Studies show we often assume things haven’t changed, when in fact they have.

New experiences don’t fall on a blank slate; we don’t merely record the things we see around us ‘as they are’ (if such a thing exists).

Everything we do, have done to us, think or experience, is affected by past thoughts and things that have already happened to us.

As a result we can’t help but put our own personal spin on our memories.

The self-consistency bias is a sin of memory

It’s this ‘spin’ that is the sixth of Daniel L. Schacter’s seven sins of memory: bias (Schacter, 1999).

The consistency bias is one of the most fascinating biases acting on our memories.

The finding is not that dissimilar to cognitive dissonance, that we will often reconstruct the past to make it more compatible with our current worldview.

Studies have shown the bias operating in both our personal relationships and our political attitudes.

Political self-consistency bias

Is it possible that we might re-write our attitudinal autobiographies so they fit more closely with our current position?

Do we effectively lead ourselves to believe that what we think today about, say, our country’s foreign policy, is what we’ve always thought?

How have your politics changed over the last decade?

Chances are that you underestimate how much your attitudes have evolved.

So says a study into people’s political beliefs carried out by Greg Markus from the University of Michigan (Markus, 1986).

Markus used data collected about political opinions from two generations, at two points in time, once in 1973 and then again in 1982.

Eight-hundred and ninety-eight parents, along with 1,135 of their offspring provided data on their attitudes towards issues like gender equality, rights of the accused and the legalisation of marijuana.

The results showed that overall, as is often noted, both parents and their children became more conservative as they got older.

But all the fun started when people were asked to think back to the beliefs they had reported almost ten years ago.

On average, only about a third of people correctly recalled their political positions from 1973, nine years later.

The same proportion of people recalled their position incorrectly by 3 or more points on a 7 point scale.

The rest were somewhere in between.

So people weren’t that good.

But maybe this isn’t surprising: people often have considerable difficulty dredging up their current political beliefs, let along those from 9 years ago.

But if people had just forgotten their previous beliefs, then it seems unlikely that their guesses should be systematic in any way, and yet they were.

Much more often than not, people guessed their remembered attitudes as closer to their current attitudes.

Effectively, people who supported the legalisation of marijuana in 1973, but had actually changed their minds by 1982, were then more likely to say their attitude in 1973 was more anti-legalisation than it actually had been.

This might help explain why people think their politics hasn’t changed much over the years, when in fact the exact reverse is often true.

Markus also found that one exception to the consistency bias was when people’s political opinions were more available to memory, e.g. when their feelings were strong on a particular issue.

Then those opinions were more likely to be correctly recalled.

This consistency bias isn’t just seen for political beliefs, though, it can also strike closer to home.

Commitment bias in relationships

Elaine Scharfe and Kim Bartholomew from Trent University and Simon Fraser University used a similar approach to the political study, but this time focussing on people’s romantic relationships (Scharfe & Bartholomew, 1998).

They asked people to rate the stability of their relationships at two points, 8 months apart.

Then, at the second time-point they were also asked to rate how they remembered their relationships 8 months ago.

Compared to the political study, people did better with their romantic partners.

The majority of people were reasonably accurate at remembering the state of their relationships from 8 months ago.

This might be expected because of the shorter gap in time and because of the more personal nature of the questions.

Despite this, those who were relatively inaccurate still displayed a consistency bias.

This meant that, for example, if their relationships had improved in the intervening 8 months then they tended to assume it had always been that way.

It’s interesting that although the consistency bias is weaker here, it’s not gone altogether.

The change bias

While the consistency bias is important, sometimes our memory biases work in the exact opposite direction, and we assume more change has occurred than really has, especially if that’s what we’re expecting.

A common example is when we’re trying to learn a new skill.

If we put loads of effort in to learning that new skill, we often think our improvement is much greater than it really is.

Michael Conway and Michael Ross at the University of Waterloo in Canada examined just this phenomenon in research into people’s study skills (Conway & Ross, 1984).

Their study relied on the fact that so-called ‘study skills’ courses seem to have little impact on people’s academic achievement.

In their experiment all the participants were first asked to evaluate their own study skills, then one group took a study skills course while the other group was assigned to a waitlist.

After three weeks both groups were asked to evaluate their study skills before the course.

The group who had taken the course were more likely to evaluate themselves as worse before the course, while the waitlist control group showed no systematic biases.

Sure enough at the end of term, the study skills group did no better than the control group in the exam.

Despite this, when the study skills groups were asked about their performance 6 months later, they thought they had done better than they had.

Again, no systematic biases were seen in the control group.

Although this effect is often referred to as a change bias, it’s really just another form of consistency bias.

People are again extrapolating backwards using the changes they think ought to have (or not) occurred over that period.

It just so happens that instead of assuming their political beliefs or relationship will be the same, this time they’re assuming their study skills must have been worse before they started the course.

Once again, people are fighting for consistency.

One bias among many

The consistency bias is only one of the many types of biases that our memories demonstrate.

Here are a few more examples:

• Beneffectance: we tend to believe the past glories were the result of our actions, while past disgraces were someone else’s fault.
• Reminiscence bump: the fascinating finding that we remember more events from our adolescence and early adulthood than from other periods of our lives.
• Hindsight bias: that we tend to think that we could easily have predicted past events when in fact we can’t.
• Rose-tinted specs: remember how wonderful things were in the olden days? It wasn’t that good, trust me, nostalgia isn’t what it used to be.

And this is just a few of them, a full list would probably need several books.

Why memory biases are useful

Like the other so-called ‘sins’ of memory, the biases displayed by memory are often by-products of their central purpose.

Building up cognitive maps of what we expect from the world helps us navigate through it successfully.

If you’ve found from past experience that going to a bar and knocking people’s drinks out of their hands tends to correlate with visits to the emergency room, you can learn something.

The fact that these ‘maps’ also impinge on our recollections of past events is a small price to pay for the advantages we gain.

Some memory biases might even be directly useful to us.

To take the two examples discussed here, believing that we are more consistent than we really are in our political beliefs and our relationship choices might help to boost confidence in ourselves.

Similarly, believing that putting in effort leads to improved performance helps motivate us to put in effort next time as well.

Factors such as these may all contribute towards our overall satisfaction with life.

So, maybe while we should be suspicious of our biases, we should ultimately be thankful for our inconsistencies.

→ This post is part of a series on the seven sins of memory:

1. Short-Term Memory vs. Long-Term Memory: Definition And Examples
2. Absent-Mindedness: 2 Factors That Cause Forgetfulness
3. Tip-of-the-Tongue Phenomenon Or Lethologica
4. Misattribution: How Memories are Distorted and Invented
5. Suggestibility: How Memory Is Biased By Suggestions
   • False Memory: Dramatic Examples Of Fake Memories
6. Commitment and Consistency Bias: How It Warps Memory
7. Long-Term Memory: When Persistence Is A Curse

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Suggestibility of memory in psychology is a major contributor to wrongful convictions, through biased eyewitness testimony.

Suggestibility in psychology refers to the tendency to fill in gaps in memory with information from others that may well be incorrect.

When people are experiencing intense emotions, they show more suggestibility.

In addition, some people display more suggestibility than others, such as those with low self-esteem or who are less assertive.

Suggestibility involves false memory

Suggestibility, one of Daniel Schacter’s sins of memory, is a close cousin of misattribution.

Like misattribution, suggestibility involves the creation of a false memory.

But, while a misattribution is of our own making, a suggestion comes from someone else who is, whether intentionally or not, influencing us.

Human suggestibility has many implications, but some of its most devastating consequences have been played out in the criminal justice system.

Criminal justice systems around the world have treated human memory with undeserved reverence for a long time, while ignoring our inherent suggestibility.

Dubious eyewitness testimony has frequently secured convictions for the most serious of crimes.

Even more incredibly for students of scientific psychology, repressed memories rising to the surface decades after the original event have been accepted by courts as the basis to lock a man away for the rest of his life.

Given the right circumstances people will finger the wrong suspect in a line-up, manufacture false memories and even change their beliefs after having their dreams interpreted.

Example of suggestibility in eyewitness testimony

Faulty eyewitness testimony is one of the leading causes of wrongful convictions in the US.

On the basis of mounting evidence, psychologists have argued that a major contributing factor to these wrongful convictions is suggestibility (Schacter, 1999).

Dramatic evidence for how easily eyewitnesses are swayed through suggestibility comes from a study carried out by Gary Wells and Amy Bradfield at Iowa State University (Wells & Bradfield, 1998).

Like many of the best studies it is deceptively simple, but its implications for the criminal justice system are profound.

Spot the gunman

Participants were asked to watch 8 seconds of grainy security camera footage showing a man walking into a store.

The footage was slowed down so that participants could get as much information as possible.

The quality of the video, however, was not that good.

After watching the video, participants were told that the man is a murderer.

Just after the footage cuts away, the man shot and killed the store’s security guard.

This information is not misleading – the CCTV footage is real – as is the subsequent murder of the security guard.

Participants were then told that their job is to identify the killer from a five-person photospread.

This photospread was identical to the one used in the real case except – and here’s the twist – the real gunman has been removed.

Having been told, though, that the gunman is in the photospread, all the participants identify one of the men.

This is where the experimenters got clever.

They then introduced three different experimental manipulations:

• One group of participants were given no feedback on their choice of suspect.
• The second were told they had made the wrong choice from the photospread and that the answer was one of the other men.
• The third group, though, were congratulated: “Good, you identified the actual suspect.” Although, of course, they hadn’t – no one had.

After this, participants were asked about many aspects of their identification including how certain they were, how good their view of the gunman was and their ability to make out the details of his face.

That’s him, I’m sure!

The results showed that simply congratulating participants on choosing the right suspect had a huge effect on their reports when compared to those told nothing and those told they were wrong.

Those given positive feedback were suddenly much more sure they were right, thought the identification was easier, had a better view, thought their judgement was more trustworthy and would be more willing to testify.

Those given positive feedback even placed more confidence in their own ability to identify the gunman.

Remember that everyone is providing these reports based on exactly the same piece of store camera footage.

Also, remember that everyone is wrong because the real gunman has been removed from the photospread!

Confidence boosted through suggestibility

The surprising thing about this experiment is what a massive effect a simple statement had on such a wide variety of factors.

Giving positive (although incorrect) feedback to participants catapulted their confidence in their identifications much higher than they would have been otherwise.

On a 7-point scale only 15 percent of the eyewitnesses who were given negative feedback rated their confidence in their identification at either a 6 or a 7.

Compare this with the eyewitnesses given positive feedback – 50 percent rated their confidence at either a 6 or a 7.

Participants given positive feedback even thought the security camera footage was clearer.

47 percent rated it at a 6 or 7 out of 7, compared with none of the eyewitnesses given negative feedback.

In a second part of the study, the authors wanted to see whether people have any idea that the feedback they receive affects their confidence in identifying the gunman.

Despite the fact that it did have a substantial measurable effect, people denied the feedback had any influence whatsoever.

Feedback to eyewitnesses is still routine

Given the huge effect that feedback can have on confidence, given human suggestibility, clearly eyewitnesses should not be told whether they have identified the suspect or not.

Wells and Bradfield (1998) point out that even when witnesses are not given verbal feedback, it is virtually impossible for police officers to avoid information leaking out through body language.

The solution suggested by Wells and Bradfield (1998) is that those administering the photospreads to eyewitnesses should be blind to the real suspect.

A statement should then be taken before eyewitnesses discover whether they have picked the suspect, and their judgement is affected.

Although they may subsequently inflate their claim, at least this can be compared with their original statement.

Incredibly, ten years later, it is still routine practice in the US and UK for many police forces to provide positive feedback to witnesses.

This is perhaps unsurprising given the police’s interest in securing convictions.

Positive feedback will almost certainly bolster witnesses’ confidence because of their suggestibility, thereby improving the impression they make in court.

Moves to reform police procedures in the US have foundered despite the repeated confirmation of this study’s findings.

Similar moves are afoot in the UK, but changes have only so far been made in some police forces.

→ This post is part of a series on the seven sins of memory:

1. Short-Term Memory vs. Long-Term Memory: Definition And Examples
2. Absent-Mindedness: 2 Factors That Cause Forgetfulness
3. Tip-of-the-Tongue Phenomenon Or Lethologica
4. Misattribution: How Memories are Distorted and Invented
5. Suggestibility: How Memory Is Biased By Suggestions
   • False Memory: Dramatic Examples Of Fake Memories
6. Commitment and Consistency Bias: How It Warps Memory
7. Long-Term Memory: When Persistence Is A Curse

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