[Music] welcome to psych boost this is the memory unit over the course of the next six videos we're going to look at two moles of memory we're going to explore different types of long-term memory find out reasons we forget and look at problems with eyewitness testimony and how police can improve eyewitness testimony now many of the topics in the memory unit come from an area of psychology called the cognitive approach and you might want to watch my videos on the cognitive approach either before or after these videos in this first video we're going to cover the multi-store model the stores it's made from the features of each of these stores and how information flows through it and of course some evaluations of the model psycboost.com over 170 videos to help you with your qualification and patreon supporters can access bonus resources tutorial videos and the discord channel features of the multi-store model created by researchers atkinson and schiffer in 1968 this is the multi-store model it's an information processor model it's linear meaning information is moved through in one direction and the stools are passive meaning they just hold on to information the stores are sensory register short-term memory and long-term memory i'm going to describe them in detail in a moment but before i start as we go through them keep in mind we need to remember three features of each of these stores their coding capacity and duration coding is a format the information is stored in so in a similar way that your phone's memory will store image and music files differently the brain is thought to have different ways of coding information capacity means how much can those stores hold and duration is how long the information can be held for okay so i've made those terms clear we can describe the model starting with sensory information if you consider the five main sensors the information they collect needs to be first detected by sensory neurons and then received by the brain the store that directly receives sensory information is called the sensory register now as the five sensors are coming from very different sensory organs we would say the coding is different for each sense impression we could give the names for each form of coding so iconic auditory haptic gusty and olfactory but in the exam we can just say the coding of the sensory register is modality specific it depends on the sense organ the capacity of sensory register is very large potentially unlimited it's hard to put an exact number on how big it is but think of it this way your brain needs to detect all the sensor information you receive in each moment all of that visual information coming into your eyes and all the sounds that you hear even all the touch sensations from all across your body the taste in your mouth and smells are detected by the sensory register now i'm not saying you're always consciously aware of those things but the brain is receiving those sense impressions constantly the sensory register has a very short duration again this varies between the different stores but we can use the figure of 250 milliseconds so a quarter of a second so the century register has a short duration before information is lost now of course as i said you're not consciously aware of that massive amount of information coming in for that we need to pay attention maybe to a particular sound or object in our vision so information moves from the century register to the next door short-term memory through attention any information that isn't paid attention to is lost we say short-term memory coding is acoustic so information in the form of sound and it feels like that if you need to remember a list you may repeat it over and over again in your head with an inner voice the capacity of short-term memory is seven items plus or minus two so some people have a slightly worse short-term memory and some people have a slightly better one the duration of short-term memory is between 18 and 30 seconds meaning information that isn't maintained by sub-vocal repetition is lost from short-term memory after that much times passed information can be passed to the final store by rehearsal now this can either be maintenance rehearsal which is keeping it in short-term memory by repeating it again and again and again in a rehearsal loop until it then passes into long-term memory or information can be passed to long-term memory in a process called elaborative rehearsal and this means by linking the new information to knowledge we already have in long-term memory information from short-term memory that isn't passed into long-term memory is of course lost and this could be due to displacement because of the small capacity new information comes in and displaces what used to be in short-term memory or it could be because of decay if the information is not rehearsed it simply disappears over time the coding in long-term memory then is semantic coding the memory is stored as part of a set of meaningful connections to other stored information so as an example we have a semantic connection between the word wave and the idea of a wave of water or waving your hand and recently you may have developed a semantic connection between the word wave and an increase in illness now i'm going to say both the capacity and duration of long-term memory is very large potentially unlimited and that's because we haven't found the limit the oldest people can still record facts on their childhood and we don't see a point in which brains get completely full up of information and can't fit more in but we do forget things so we could argue that information is lost but as we'll see in a future video maybe that information isn't truly lost maybe we just lose the ability to access it and could recall it if we had the right cue so that's the multi-store model we need to describe the model the process information passing through the model but also the coding capacity and duration of each store and here they all are in a table you may want to copy down both the model and this table down and make sure you can recall it from memory in the evaluations i want to cover the research that revealed all of these features of the multi-store model of memory and how we could evaluate that research research evidence for the multi-store model to start with just a simple piece of research by glasner in 1966 showing the primacy recency effect when participants were asked to recall a list of words participants tended to remember the first words in the list and the last words in the list but struggle to remember the middle words now this suggests that long-term and short-term memory are separate processes with the first words in the lists having moved into long-term memory and the last words in the list displacing the middle ones and taking their place in short-term memory the first feature of the stores that i'm going to evaluate is the capacity of the century register and this was a study by spirling what spieling did was he flashed a grid of 20 letters onto a screen for a 20th second and then got the participants to immediately call one row of letters now because it would take too long to say the middle row or the top row you use different tones for each run let's have a go so what were the letters i imagine that was a little too fast but spieling found that with some practice the participants were very accurate now i'm going to argue that short-term memory only has a capacity of between five and nine items to be able to accurately recall a full row sensory memory would have to hold on to all 20 letters in that moment now this suggests that sensory memory has a much larger capacity than short-term memory and we're only considering here visual or iconic sensory memory moving on from sensory memory this is a study that demonstrates the coding both of long-term and short-term memory it's a little complicated but stay with me because we're going to be able to evaluate the coding in both long-term and short-term memory with just this one study badly gave his participants wordless to recall these word lists were either acoustically similar acoustically dissimilar semantically similar or semantically dissimilar now badly had as participants i recall immediately test in short-term memory or after 20 minutes testing long-term memory and the results showed the worst recall in the immediate recall condition was for the acoustically similar words now badly argued that this showed short-term memory is coded acoustically the acoustic similarity of the words course and confusion now students often struggle with the conclusion of their study and it's a little counterintuitive to say because short-term memory is coded acoustically words are acoustically similar are harder to recall well to help you try and remember i'll give you a metaphor of a filing cabinet if it's coded or organized alphabetically then if we have a bunch of files that are stored across the filing system when we want to retrieve one it's easy but if all the files are similar it could be more difficult to go in and get the file that we want now let me be clear i'm not saying that we all have individual files to store our memories it's just to help you remember that if a storage system is organized or coded in a certain way if all the items are similar it could be more difficult to recall those individual items moving on to the capacity of short-term memory we have very old research by jacobs that showed when asked to recall lists of numbers people could recall around nine when tested with letters around seven was the average now there was a bit of a range in what could be recalled some people are a little better some a little worse so what we can say is the capacity of short-term memory is seven items plus or minus two now this research really showed that the capacity of short-term memory is small however miller points out that we can increase the capacity of short-term memory by chunking this is making small sets or groups of items effectively reducing the number of items overall and finally for short-term memory we've got duration to test this peterson and peterson asked participants to recall trigrams now these are sets of free letters that don't have a meaning so hfd or tku and peterson and peterson used an interference task to stop participants just using maintenance rehearsal so repeating the trigram to keep it in their head and this was by asking the participants to count backwards it was found in this study that the duration of short-term memory was between 18 and 30 seconds moving on to long-term memory we can use the same body study again and we find that recall after 20 minutes so when testing long-term memory was worse for the list of semantically similar words this semantic similarity is causing confusion suggesting that long-term memory is coded semantically now capacity and duration is potentially unlimited and there's no real way to test that but we can look at two studies that at least show the capacity and duration of long-term memory is very large firstly a researcher called wagner who created a diary over the course of six years and in that time made more than 2 400 entries when tests on events there was a 75 recall after one year 45 after five years since making the entries now this suggests a capacity of long-term memory is very large barracks showed old photographs of school friends to participants between the ages of 17 and 74. after 15 years recall was 90 and even after 48 years the recall was 80 and this does suggest that the duration of long-term memory is very large potentially unlimited additional evaluations of the multi-store model before we finish we could be expected to evaluate research on the multi-store model of memory and we want to be able to give overall evaluations of the multi-store model itself and we've got a few options now one of the most obvious evaluations is much of the research that i've outlined seems like a very artificial way of testing memory it's not really like how we use memory in our day-to-day life now there are a few aspects of this the lab environment itself is unusual not really reflecting the places that we recall like school and work if we can't apply the findings to those environments we would say the findings lack ecological validity the tasks the participants are asked to complete are often not like the tasks that people do in day-to-day life so we can say the tasks lack mundane realism what i've done here is question the external validity of this research suggesting we may not be able to apply what we found about memory under experimental conditions in situations outside of the experiment but in defense of psychologists experiments have to be designed to make measurements possible it may be the only way of scientifically testing the limits of memory this is because we're not able to directly observe memory psychologists have to make inferences these are educated guesses about the underlying model based on the behavior observed in an experiment now this is a problem because those inferences could be wrong it could be a completely different process that produces the same observed behavior an interesting point about the large capacity and short duration of the century register it's supported by evolutionary theory in the wild we'll need quick reactions for survival taking in as much information as possible but only keeping and processing the important information holding onto and then processing too much information would slow down reaction speed making your lunch and a criticism of the multi-store model is it's a little simplistic it suggests short-term memory and long-term memory are unitary and passive stores meaning they're just one thing and they're just holding on to information but from research we're going to see in future videos they're clearly multiple types of long-term memory and short-term memory isn't unitary it has a number of components that are active they work in information together passing and then processing information between them and even some basic assumptions of the multi-store model lack face validity we clearly have long-term memories that are of taste and smells and the capacity of short-term memory isn't fixed it changes over a lifetime and with practice have a go at this real exam question on the multi-stop model if you're a psych boost patron at the neuron level and above you can access the tutorial on psycboost.com and in it i'll talk you through a model answer to this question general tips so don't forget to subscribe so you don't miss the videos released right up to your exams and i'll see you in the next cycles video types of long-term memory you