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.


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