Memory: Explanations for Forgetting

I’m assuming everyone reading this has forgotten something, at some point in their life.  If you haven’t, I’m impressed, and would like to ask you to tell me your secret in the comments, because I could really do with that kind of magic in my life.

We’ve got two different explanations for forgetting: interference and retrieval failure.  I’m sorry to tell you that interference is confusing as heck, and that’s why it’s the one we’re starting with.

There are two types of interference: proactive and retroactive.  Proactive interference is sort of like interference going forward, and it’s when past learning interferes with current attempts to learn something.  I imagine that this is sort of like the stories I’ve heard about when people start taking a science at A Level, and the first thing their teacher tells them is that everything they learned at GCSE is incorrect.  Underwood found that when participants in an experiment were given multiple word lists to memorise, they performed more highly on lists learned earlier than lists learned later.  Participants who had only learned one list had a recall of 70%, whilst those who had learned 10 lists had a recall of only 20%.  Kane and Engle found that participants with a greater working memory span were less effected by proactive interference than others, suggesting the role of individual differences in interference.

Retroactive interference is like interference going backwards.  It’s when current learning interferes with remembering past learning.  That probably best applies to when you have to put down something like your previous two addresses, and you can only remember your current address.  A researcher called Georg Muller was the first person to study retroactive interference.  He gave participants a list of nonsense words to remember and gave half of them an intervening task, then tested them again six minutes later.  Those who had been given an intervening task did poorly on the test compared to those who had not been given an intervening task.

McGeoch also found that if items being remembered were similar, participants were likely to find them difficult to remember.  For example, he carried out an experiment with three conditions.  In one condition, the participants were given a list of words and a list of their synonyms.  In the second, the second list was nonsense syllables.  In the third, the second list was numbers.  In the first condition, recall was 12%, in the second it was 26%, and in the third it was 37%.  This suggests that interference is stronger if items are similar.

Because similarity of items is required for interference to occur, some researchers have pointed out that interference really doesn’t happen very often.  As such, it isn’t considered to be a very important explanation for forgetting.  We still have to learn about it, though, so it sort of feels like examiners are taunting us a little bit with that one.

Baddeley and Hitch also tested a rugby team for examples of real-world effects of interference.  The length of the season was the same for all of them, but some had not played in all games due to illness or injury.  When asked to list teams they had played against, those who had played in the most games had poorer recall than those who had played in less games.  This demonstrates the effects of interference in everyday life.  We’ll do another fun Baddeley study when we get onto retrieval failure, too.  That one is up on my wall.

In spite of this real-world study, most research into interference has been quite artificial, and failed to replicate the way that interference works in real-life.  This means that it lacks ecological validity.  Others use the study by Baddeley and Hitch to counteract this, as it demonstrates a real-life effect of interference.  As with anything, there’s no right or wrong to this one – it’s up to you to develop your own opinions on it.  Additionally, Danaher studied the impact of advertising on interference and found that individuals exposed to advertisements for competing brands in a short time found both difficult to remember.  This is a problem for advertising companies, who invest a fair amount of money into adverts, only for people to get confused.

There’s also a point about accessibility versus availability.  I’m not going to talk about that as an evaluation point, because we are literally about to talk about it as a topic by itself.  The textbook I’m working from is really well-written, if you couldn’t already tell.

The proper term for accessibility and availability is called retrieval failure.  I’m sure you can already sort of imagine what this one is.  It’s sort of why you might walk into an important exam and find yourself staring helplessly at the wall.

Tulving and Thomson, because they hate us all, decided to name the main theory behind retrieval failure the ‘Encoding Specificity Principle’.  It’s okay – it’s not actually that complicated.  It just means that we find it easier to remember things if the cues present at learning are present at recall.  Tulving and Pearlstone carried out a study using fruits and word categories, but I actually think that this is best explained by using the Bahrick study we covered earlier.  Do you remember how free recall had a lower recall rate than photo recall?  The same applies in Tulving and Pearlstone’s study, where free recall had a recall rate of 40%, whilst cued recall had a rate of 60%.  Not all cues are related to the learning material – some can be things like environmental stimuli or emotional context.

This theory is a bit dangerous, though, because it’s circular.  A circular theory means that if someone remembers something, it works, and if someone doesn’t remember something… it still works.  This makes it impossible to test, and so it cannot be relied upon as a theory.

Ethel Abernathy (female researcher!  Rejoice!) studied context-dependent forgetting.  She tested a group of students each week and found that those tested in the same room as they were taught in performed better than those who were tested in a different room to the one they were taught in.  The same went for instructors, too – if students had the same instructor testing them as the one teaching them, they usually performed better than if the instructor was different to the one teaching them.  The other study on context-dependent forgetting is by Godden and Baddeley – and I quite like this one.  They got a group of scuba divers, and tested their memory under four combinations of on land and in water.  Those who had learnt on land performed better if they were tested on land than if they were tested in water, and those who had learnt in water performed better if they were tested in water than on land.  Jury is still out on how they were able to communicate underwater.  I don’t know much about water.

The other type of forgetting is state-dependent forgetting.  It was tested by Goodwin, and it is wild.  Goodwin got a group of male participants and asked them to learn a list of words when they were either drunk or sober.  Those who had learned drunk performed better when tested drunk, and those who had learned sober performed better when tested sober.  One can reasonably assume that those who were sober throughout had the best performances, but if anyone wants to buy me a drink to test that out, I will not complain.

Obviously, there’s a lot of research here, and that’s a really good thing.

Real-world applications of retrieval cues might help you in your exams.  You might not be able to revise in the examination room, but research by Smith has found that imagining the room is actually just as effective as being in it.  This is called mental reinstatement, and we’ll go over it when we cover the cognitive interview.  That being said, when you’re learning, you’re making a lot of complex associations, and a context-based cue isn’t always going to cut it.  This is called the outshining hypothesis: if a better cue is available, it’ll lead to better remembering.

I’ll point out at the bottom here, to bring both theories together, that cued recall reduces the effects of interference.  This suggests that retrieval failure is a more important theory of forgetting than interference, but be careful with those kinds of statements, because we’ve already discussed the fact that retrieval failure can’t actually be tested because it is circular.

That’s that for explanations for forgetting – the next thing we’ll talk about is the accuracy of eyewitness testimony – but I’d like to drop an email to my psychology teacher about exam technique first.


Memory: Long- and Short-Term Memory

Welcome to Memory, six days before Paper One.  If you can hear vaguely anxious noises, they’re coming from me.  Although, thankfully, I’m a bit better at Memory than I am at Social Influence, so with any luck, this won’t take too long.

The first things we’re going to talk about are Long- and Short-Term Memory, what they are, and how they work.  I mean, the whole topic is about those things, but this is your starter building block, where we’ll start to implement an understanding of it, and that sort of thing.

The first thing you need to know is that there are three key points to either side of memory: capacity, duration, and coding.  You really need to know these to understand everything else, so try to get the figures to stick in your mind as best you can.

Let’s talk about capacity first.  Capacity refers to how much information the brain can remember.  It can be pretty difficult to remember a lot of stuff at once – I’m sure everyone’s been in a situation where you’ve just woken up or just come home and a parent, roommate, sibling or spouse immediately bombards you with information of chores you need to do, and it’s just noise – you can’t take any of it in.  Capacity is the reason for this.  Your Short-Term Memory can only hold five to nine items at a time (seven is the key number here – we even refer to it in Memory as ‘Miller’s Magic Number’).  Any more than that, and the human brain can’t process the information.  We assess the short-term memory using something called a digit-span test, which I’m sure you’ll be able to find with ease on the internet.  This is, however, in contrast to the Long-Term Memory, which most psychologists believe can store information for an infinite amount of time.

Cowan, contesting Miller’s magic number, reviewed a number of studies on the short-term memory and found that the capacity of the short-term memory may be even more limited.  Cowan’s estimate was that it was more accurate to around four chunks.  A study by Vogel on visual, as opposed to verbal stimuli, found that the number was indeed closer to four chunks.  Simon also found that the size of the chunk matters, as an eight word phrase is much harder to remember than a single number.

I’m going to cease evaluating here, very briefly, to explain what a ‘chunk’ is.  The textbook doesn’t really go into it, but mercifully, I have a very good teacher who recognised this and explained it to us.  A chunk is essentially the same thing as an item; chunking is a technique we use to help us remember things, according to a three hour lecture on Lynda dot com.  This makes a lot of sense – when you have to remember a phone number, do you try and remember the whole 11 numbers, or do you break it down into three or four parts?  Most people would answer that by saying that they break it down into three or four parts.  For example, my chunking method for phone numbers is 5 numbers, then 3, then 3.  That is chunking, put simply.

The other criticism of testing capacity comes from Jacobs, who points out that there are individual differences in the duration of memory.  Eight year olds, for example, had an average capacity of 6.6 items, whereas 19 year olds had a mean average capacity of 8.6 digits.  There are a couple of theories about why this is: one suggests that people’s brain capacity increases with age, whilst another suggests that as we get older, we develop strategies to help us retain information – like chunking, which we’ve covered just above, there.

An infinite long-term memory is really nifty.  It doesn’t quite account for the fact that most of us don’t have any memories preceding our third year of life, but theories surrounding that are still very much foetal, and we don’t cover them in A Level Psychology.  If you’re interested, though, popular opinion amongst researchers is split between the lack of memory being due to trauma and the lack of memory being due to underdevelopment of the brain.

After capacity, we move onto duration.  Duration means how long things can stay in the brain for, and it has been tested in various ways.  For the short-term memory, a pair of researchers called Peterson and Peterson (married, not siblings), gave participants a consonant syllable (e.g. FRB) and a three-digit number to memorise.  They were asked to recall the consonant syllable after a retention interval of 3, 6, 9, 12, 15 or 18 seconds.  The reason for the three-digit number was to prevent participants from rehearsing the information, as this would allow it to pass into the long-term memory, therefore reducing the internal validity of the study.  The end result was that participants were 90% correct after 3 seconds, 20% correct after 9 seconds, and only 2% correct after 18 seconds.  As a result of this, it is generally believed that the duration of the short-term memory is less than 18 seconds, which – to me, at least – makes a lot of sense.  There are criticisms of this, however, which we’ll talk about shortly.

Peterson and Peterson’s study on the Short-Term Memory’s duration has also been criticised.  One popular criticism is that it’s an artificial way of testing Short-Term Memory, as memorising a random string of letters and numbers isn’t true to the things we have to remember in everyday life.  However, the study has been defended by some, who rightly point out that there are situations in which we do have to recall strings of numbers and letters.  Such examples would be car license plates or phone numbers.  More people still point out that these things have some meaning attributed to them – it’s really up to you, as someone studying the subject, to decide which side of the debate you’re on.

Furthermore, whilst the use of numbers prevented rehearsal of the letters, and therefore a transfer into the long-term memory, its effectiveness in improving internal validity has been questioned.  This is because there’s also a phenomenon called displacement in memory.  This means that a short-term memory is replaced with something else that an individual is trying to remember – such as a string of three numbers.  Reitman used auditory tones to test the short-term memory, and found that participants could remember up to 96 seconds worth of information.  This suggests that duration in Peterson and Peterson’s study may be due to displacement, rather than decay, as originally thought.

The duration of the LTM is supposedly unlimited, however, a study by Bahrick – intentionally or otherwise – calls this into question.  Bahrick tested 400 participants between the ages of 17 and 74 on their memory of their classmates under two different conditions.  One condition was photo recall, in which the participant was shown a photo of classmates and asked to name them.  The other condition was free recall, in which the participant was asked to name as many classmates as possible from memory.  Photo recall showed 90% accuracy after 15 years and 70% accuracy after 48 years.  Free recall showed 60% accuracy after 15 years and 30% accuracy after 48 years.  Both conditions suggest some kind of decay occurs during memory.  The other explanation is that cues, rather than the memories themselves, decay – which we’ll come onto in a couple of days’ time.

Finally, we have coding.  Coding is how things are remembered – or encoded, if we’re going to be technical – and we probably should be technical, as this part of psychology is quite scientific.  There are two main types of coding: acoustic and semantic.  Acoustic means sound-based – think acoustic guitar, or the acoustics in a concert hall.  Semantic means meaning-based – there’s nothing in particular that we can link this to, but it might help you to remember that there are three main facets of language, and semantics is one of them, because it refers to what the words mean.

Baddeley found that a list of words that are acoustically similar but semantically different (cat, cap, can, cad, cab, etc.) were easily confused in the short-term memory, but not the long-term memory, suggesting that short-term memories are encoded acoustically.  This makes quite a lot of sense to me, as someone who had to try and remember the words in the short term to transfer them over here (spoiler alert: they’re in a different order to the one they appear in in the textbook – this will not matter in an exam).  On the flipside, he found that semantically similar words (great, large, big, wide, tall, etc.) were confused in the long-term memory, but not the short-term memory, suggesting that the long-term memory codes things semantically.

However, Baddeley also tested LTM by waiting 20 minutes.  I’m sure that you’re already wondering whether 20 minutes can really be considered long-term memory – it isn’t short-term memory, but it’s also not really long-term memory either.  This is the conclusion that most researchers have come to, too.

Although the STM seems to rely on acoustic coding, it is thought that there is also a visual element to coding.  Brandimote showed participants an image and prevented any verbal rehearsal.  The result was that participants found a way to code the image visually, rather than verbally.

The same applies to the LTM.  Frost found evidence of visual coding taking place in the LTM, whilst Nelson and Rothbart found evidence for acoustic coding occurring in the LTM.  This suggests that coding depends on circumstance as well as the type of memory.


And that’s the different types of memory.  Next, we get to talk about the Multi-Store Memory Model, otherwise known as my favourite.

Memory: The Working Memory Model

Another day, another post.  Actually, I might schedule this post for tomorrow.  I think it makes more sense to have both models on both days.  So, uh… three posts in a day!  Wow!

The Working Memory Model is supposedly a new and improved Multi-Store Memory Model, but the two are completely different.  For one, there are more parts in the Working Memory Model.  Here’s a list of them:  Central Executive, Episodic Buffer, Visuo-Spatial Sketchpad, Phonological Loop, and Long-Term Memory.  The Visuo-Spatial Sketchpad also contains a visual cache and an inner scribe, whilst the phonological loop contains a phonological store and an articulatory process.  Lots of parts, lots of words.  Don’t worry – I’m about to go through them.  All will be fine.

Let’s start at the beginning (a very good place to start).  The Central Executive is kind of like the big boss of the Working Memory Model.  It’s mostly involved with decision-making and critical thinking.  It makes sure that the entire system carries on running smoothly, and takes over when something goes wrong.  Sometimes, it’s analogised as being like the Fat Controller in Thomas the Tank Engine, if that helps you at all with remembering it.

This being said, the definition we’ve been given of the Central Executive system is vague – like the Episodic Buffer below, nobody is quite sure exactly what it does.  Furthermore, critics believe that there must be more than one branch of the Central Executive system – one brain-damaged patient, EVR, had good reasoning skills but poor decision-making skills, which suggests that the Central Executive as a whole could not have been damaged, or both would be affected.  Essentially, the Central Executive system is too vague in its current form.

Next, you have the Episodic Buffer.  The Episodic Buffer was actually added later in response to criticisms, and it’s supposed to act as a point of transmission between the Long-Term Memory and the Central Executive Memory.  You’ll notice that this explanation is very short; that’s because nobody really knows what the episodic buffer is, or what it does.  That’s one of the main criticisms of the Working Memory Model.

Branching off from the Central Executive, you have the Visuo-Spatial Sketchpad and the Phonological Loop.  I’ll start with the Visuo-Spatial Sketchpad.  The Visuo-Spatial Sketchpad is the part of the memory concerned with visual information: it helps us to remember what things look like – their properties, such as colour – and also where they are in relation to each other.  Those things are actually covered by different areas of the Visuo-Spatial Sketchpad.  The visual cache is what stores the properties of individual objects – that’s things like shapes and colours – the basic information about individual pieces of information.  The inner scribe is what stores information about where different objects are in relation to each other – or, in shorter terms, spatial information about objects.

A patient called LH was better with spatial information than visual properties, which supports the idea that there are two branches of the Visuo-Spatial Sketchpad.

The Phonological Loop helps us deal with sound; that includes isolated sounds as well as verbal information.  It also helps to preserve the order of information, which means that information doesn’t get jumbled up in the brain.  Like the Visuo-Spatial Sketchpad, it’s split into two different parts: the phonological store and the articulatory process.  The phonological store holds information you hear directly – a little bit like the inner ear, but inside the brain.  The articulatory process processes information that you don’t hear directly, like words you read in your head.

A patient called KF is thought to have had damage to the Phonological Loop, as his short-term forgetting of verbal information was much greater than his forgetting of visual information.  However, he could recognise meaningful sounds, like a telephone ringing, but struggled with verbal material.  SC is also thought to have had damage to the phonological loop, as his learning abilities were generally good with the exception of him being unable to learn word pairs.

There are issues with using brain-damaged patients as a support, however, as most brain-damaged patients have also undergone some amount of trauma.  This means that the effects of brain damage are not isolated to physical damage to the brain, but also the psychological damage of undergoing trauma.

The Visuo-Spatial Sketchpad and Phonological Loop don’t have any direct connection to the Long-Term Memory.  Instead, all information passes back to the Central Executive, which filters through it, then transfers the information to the Long-Term Memory itself.

Some of our evidence for the Working Memory Model comes from dual task performance.  Dual task performance is based on the idea that if one part of the brain is performing a task, it won’t be able to perform a second task, but another part of the brain will be able to perform a task.  That isn’t worded very well, but if you’re listening to music and drawing, the drawing is concerned with the Visuo-Spatial Sketchpad and the music is concerned with the Phonological Loop, so you can do both.  This was demonstrated by Baddeley and Hitch, who used processes involving the Central Executive and the Articulatory Process, which had involvement from the Central Executive in one condition, to examine the effects of dual task performance.  The tasks were both quicker if the second task did not also involve the Central Executive.

That’s the Working Memory Model!  Next up, we’ll be going through the types of long-term memory.  I like that one – it means I get to crack out the analogies and anecdotes!