back in the 19th century psychologist Hermann ebbinghaus proposed Decay Theory this simply stated that all that was needed for you and I to forget was the passage of time forgetting happened just by default the memory Fades away but is this really enough to explain why we forget hey everyone welcome back to Bear to mind in this video we're exploring why we forget things from our long-term memory and whilst memories certainly do fade away as time goes on there are many other explanations for why we forget we're going to explore two of them starting in this video with the idea of interference foreign often when we learn and encode information into our memory a certain amount of time goes by before we try to recall that information during that passage of time we're not simply sat there doing nothing we're most likely engaged in some other tasks in the life of a student you've probably just finished one class and then you're straight off to another class in another subject well what if these tasks interfere with your earlier Memories the main idea behind the interference explanation is that we tend to forget when two memories get confused with or become mixed up with each other other information in our memory interferes with these memories the more similar information is the more it's thought to lead to interference the first type of interference is known as pro-active interference this is when all or existing memories in our long-term memory affect new memories in other words interference goes forwards the second type of interference is known as retroactive interference this is when new memories from new learning affect old or existing memories in other words interference calls backwards a simple way to remember these two types of interference is to think that proactive interference p is where past memories interfere with the new learning and then retroactive interference R is where recent learning interferes with the old information for example when I park my car at work I tend to park in the same space or part of the car park each day but one day I arrive at work and all the spaces in that part of the car park are taken so I have to park further away and use a new space however at the end of the day when I go to look for my car I cannot find it and the thought even flashes through my mind that someone's stolen it but no have just forgotten where I parked it is this an example of Proactive or retroactive interference the this is an example of proactive interference the old information from the past where I normally parked my car has interfered with my new information of where I parked my car that day I'll put a few more examples on the screen for you to practice you can pause the video and see if you can identify whether they are examples of pro or retroactive interference [Music] all right let's consider some of the research into interference firstly there is laboratory research by mcgow and McDonald in 1931. participants were given 10 words to learn and practice remembering the list until they could recall them with 100 accuracy they then learned a new list notice that this is testing retroactive interference they wanted to see if the more recent information the new list would interfere with the first old list there were six groups in the study Each of which had a different list to learn the lists varied in terms of how similar it was to the original list Group 1 had synonyms these are words with the same meanings as the original list group 2 had antonyms these are words with the opposite meanings as the original list group three these were words unrelated to the original ones group four they simply had consonant syllables group five they had a three digit number list and group six they were given no new list at all they just got to rest they were the control condition here's what they found when participants were asked to recall the original tem words recall was the worst or we could say forgetting occurred the most when the new list was similar to the the original old list of words the synonyms cause the most confusion this study nicely demonstrates how interference can cause forgetting and particularly so the more similar the material is however one of the criticisms of such research is the use of artificial tasks to study memory this is often the case with laboratory research where they have high control of their variables however you can see that most of the second tasks each of the groups carried out are artificial and not typical of everyday memory use for example how often do we try to learn a list of words that all have the same meaning or a list of three digit numbers also for interference to occur two memories have to be fairly similar in order to interfere with each other this may happen occasionally in everyday life for example if you were to revise similar subjects closing time but this doesn't really happen that often as a result the interference explanation of forgetting is sometimes questioned when it's based on Research that lacks ecological validity let's now move from a laboratory-based experiment to a real life study badly and hitch decided to conduct Research into forgetting with rugby players they wanted to find out if interference could better explain forgetting than simply the passage of time so they asked rugby players to try to recall the names of all the other Rugby teams they'd played so far during the season the same amount of time had passed for all the rugby players but they hadn't all played the same number of games because of injuries what they found was that the amount of time the had passed was not a key factor in their ability to recall they didn't have trouble recalling the matches they played at the beginning of the Season what actually influenced their memory was how many games they'd played between their last game and all the other games for example if between their last game and the team they played five weeks ago there were four other teams that played it was a lot harder for them to accurately recall than the rugby players who hadn't played for five weeks due to injury this study shows that interference can explain forgetting in at least some real world situations which adds credibility to the theory however one limitation of the interference explanation is that it can be overcome by using cues research by tolving and soccer in 1971 gave participants five lists of 24 words that were made up of categories however the participants were not told explicitly that they were in categories as they were mixed up for example they will be given words like this Can you spot the categories in those lists the researchers assumed that it would be obvious to the participants they found that for the first list recall was around 70 accurate but recall of this first list got worse after each new additional list of 24 words they were given to learn presumably this was because of interference however the researchers then did something rather clever they gave the participants a cued recall test they gave the participants the categories for the word lists that they had not given them at the start what difference did this make memory recall improved back up to 70 again this shows that interference causes a temporary loss of accessibility to memories that are still in long-term memory but this can be overcome with the use of cues in fact for more on the importance of cues with forgetting check out this next video on retrieval failure which has some real practical advice to help with your studying and revision I hope you found this video helpful we'll see you in the next one