March 2, 2006

Memory

• False memory: people remembering events or things that never actually took place.
• Memories don’t record things like a tape recorder.
• Memories aren’t designed to accurately store past events.
• Memory has very little to do with the past.
• It is actually designed to help you function in the present.
• Memory is designed for survival and reproduction.
• It wants to adaptively store past experiences.
• It alters events.
• The different structures of memory:
• From the earliest writings s of memory, it became clear that there must be at least 2 memory systems. It seemed clear that there is an immediate sort of memory; it allows you to function in the immediate environment.
• There must be a sort of longer term memory- it recalls things from the immediate memory at a later time.
• It allows you to carry on a conversation and allows you to pull out something form the particular event later on.
• Experimental demonstration that tried to demonstrate the differences in the 2 systems:
• 1. serial order test- giving subjects a long series of words or items that they have to try to remember. When they did this, their memory tends to be best for items at the beginning of the list and at the end of the list. Items at the beginning are called primacy or primacy effect. They are thought to be remembered best because you have the longest amount of time to recall them. This is for longer term memory. The last items are called the recency part of the effect or recency effect. This is the most recent items and if anything is in the immediate system it is these items. Subjects often give off the last items and then go back and give the first items from the longer term memory.
• There is also evidence from brain damaged subjects that further confirm the 2 systems.
• One of the most famous cases is a guy named H.M. He had severe epilepsy. His epileptic seizures were so bad that they had to do radical brain surgery on him to relieve it. In the course of doing this, a particular structure, the hippocampus, was removed, which is important for memory. A piece of the evidence that tells us about the hippocampus being important for memory is from H.M. The surgery left him with a severe memory deficit. He was no longer able to store any new long term memories. He recalled old memories from before his surgery but his ability to form memories was severely impaired as a result of the surgery. This showed that there must be 2 memory systems in order for them to be disconnected.
• In the late 1960’s or early 70’s, a couple of researcher named Atkinson and Shiffrin did their best to try to review and put together all of the research that had previously gone on. Their goal was to create a comprehensive model of how memory works. They concluded that memory is not a 2 system structure, but a 3 system structure. They created a 3 box model called boxes in the head. This was a model of memory. There is an immediate and longer term memory and also a sensory store or sensory register.
• Sensory register: an extremely brief from of memory that is associated with each of the senses. All of the senses have the capacity for sensory register. It can last for as second or half of a second after the signal has stopped. Sensory register of the eyes is iconic memory or iconic storage. It had the greatest amount of research.
• Cattel, Erdman, and Dodge: late 1800’s or early 1900’s- did a classic study that indicated that iconic memory had the capacity for 4 or 5 bits of information. Today we look back at their studies and refer to them as whole report studies because the subject had to look at an array of letters that were flashed quickly and the subject had to report as many as possible. The perfect subject would report the whole thing, hence the term whole report. The subject typically only reported 4 or 5 bits of information.
• 1960-George Sperling- looked at old studies and criticized them. He concluded that there was something flawed in their studies and that they had been underestimating how much iconic memory could actually hold. He said that when letters are flashed quickly the subject seemed to be reading off an image that isn’t there anymore. He said that the image was deteriorating and fading away. He said that were only reporting what they could before the image faded away. He devised a partial report. A matrix of letters is flashed at the subject: M Q D
                          L T R
                          Z X A
• He wanted them to be discreet, independent bits of information. It is flashed for a quarter of a second and immediately after a tone is flashed and played. It his either a high, medium, or low tone. The pitch of the tone indicates a row of the matrix that the subject is supposed to report. A high pitch indicates the top row, a medium pitch indicates the middle row, and a low pitch indicates the bottom row. The tone came up randomly. If the subject is able to report a row completely and they don’t know which row they are going to report, this shows that the 3 rows are available in their iconic memory. The entire matrix is present so there is at least 9 bits of information available to it. The subjects reported less and the capacity of iconic memory is more. All nine have to be available to report the 3 rows.
• He then added more letters to the rows, giving 12 to report. When he did this, their ability declined somewhat. He then concluded that the capacity of iconic memory is 9-12 bits of information. He then asked how long it will last. A delay was inserted between the matrix and the tone. When the image deteriorates, this shows how long it lasts. When you start to reach a quarter of a second, performance starts to decline. Dull images= shorter duration. Duration is 1/3 or ¼ of a second.
• Studies done after Sperling question his studies and said that he may have been too generous. They thought the duration was 1/10 of a second at the shortest end and ¼ of a second at the longest.
• The other sensory register studied was done of the ear, called the echoic memory. It does appear to be substantially longer in duration than iconic memory. It can go up to 4 seconds if the noise is loud.
• Representation or encoding of information: sensory register doesn’t like to goof around with information; it encodes information as it was experienced. It retains a raw sensory trace of that experience. It doesn’t try to transform or change it in any way. Information is presented exactly as it was presented.
• How the image is lost: image is lost due to time. As it goes through time, it decays. It goes away after a second or two. Atkinson tried to show why we needed this system. Every system does different things. They don’t duplicate each other in any way. They hold different amounts and lose it in different ways. They are very unique.
• Short term store: immediate memory system. It is also referred to as working memory. It allows you to function and operate in your natural environment. It allows you function on a day by basis.
• What is the capacity? It is supposedly spelled out in a clear way by George Miller in the later 1950’s. He wrote a famous article called “the magical #7”. He went back and reviewed of the data he could find about the immediate memory at looked at the way society presented information to people. He concluded that the immediate memory could hold 7+- chucks of information. He argued it seems like there are 7+- slots on immediate memory. Once slots are there, the capacity is achieved. Access is denied when filled up. TI is limited and once filled up, something has to give. Chunks of information: rather flexible and can change in terms of their density. Chunk: any meaningful unit of information. Any meaningful unit can be dense and large or small and dull.

March 7, 2006

• Chunks vary in their density, according to Miller.
• A meaningful unit can be something as small as a single letter, a whole word, or an entire paragraph. If binded together in a meaningful way, it will be a meaningful unit.
• As familiarity with something increases, the binding is enhanced. As you come more of an expert of become more familiar you aren’t adding more slots, you’re increasing the density of the individual units you can fit into the slots of working memory.
• Experts vs. Novices:
• How is it that people become experts and what distinguishes them?
• Chase and Simon: famous for their studies looking at chess experts. What knowledge makes them an expert chess player? They looked at a number of factors and variables. They got a group of international grand master chess players together and they also got a group of early players together. They were compared on a number of variables such as- general memory capacity. Are the grand masters better than others because they have a better memory? This is false. Do they have better problem solving skills- this is also false.
• Their memory for chess arrangement of pieces- there was a random arrangement of chess pieces and they were allowed to look at the arrangement for 15 seconds and then were told to reconstruct the arrangement. Random arrangement showed no difference. Then they did a slightly different test. They took arrangement out of actual games. The arrangement represented something. It was meaningful for them. They were allowed to look for 15 seconds and asked to reconstruct. This measure revealed a big difference between novices and experts. Expert chess players were far more able to reconstruct meaningful arrangement of the chess pieces. A novice looks at the board and tends to look at it piece by piece. Each piece is something meaningful for them.
• The expert tended to look at larger pieces on the board. Sometimes the entire arrangement on the boards was something meaningful to them. They looked at larger arrangements, not at the individual pieces. The larger the units, and the larger the pattern, the more of an expert you are.
• Duration of working or short term memory: the duration depends on what your focus of attention is. Something can be kept alive in working memory as longs as you’re willing to dedicate resources to it. It will leave your memory when you start focusing on something else. It can be kept alive in your working memory by rehearsing it. It is usually there long enough to function with it. It can be varying durations.
• Brown-Peterson Technique: named for Brown and both of the Petersons. Their study: gave the subject 3 letters that aren’t supposed to be a work and they are supposed to remember these 3 letters. EX: T, K, B. Their working memory shouldn’t be strained. Immediately after they are given the letters, they are given the numbers 5, 6, 7 and they have to county backwards from the number by 3’s. This is supposed to prevent them from rehearsing the 3 letters. They would be tested on it later on. The studies varied. When around 20 seconds or so, the 3 letters are lost. This was how long the duration was without rehearsal. Other studies said it was around 30 seconds. So it was said that the duration is 20-30 seconds.
• Representation: STM likes to operate using verbal or acoustic codes. It is represented by some kind of verbal code that can be repeated or rehearsed.
• Conrad: confusing matrices. He studies STM and how it likes to represent or encode information. The subjects set in front of a computer screen and they look at individual letters. There are no sounds or words, just letters flashing at them. Subjects are asked to recall letters in the order in which they were presented. The subjects had to fill in all of the blanks, regardless if they remembered all letters or not. Nothing can be left blank. He was actually interested in their mistakes. When they guess, what kind of guess do they make? Somewhere in between the letters, the correct response is P. They can’t quite remember what’s there, so they guess. They guess something like F because it is visually similar to P. Maybe their mistakes are made by confusing visual features or images. Another possibility is they fill it in with something like G. G sounds like P. They have similar acoustics. This is what the subjects did. The subjects almost never used the F in place of P. They almost always used G because it sounds like it. All errors were acoustic errors. Memory is taken in with a verbal code which allows for repeating it in your head. Does this preference mean that it is what it is limited to? No, there is evidence that STM can represent information in other ways. It just prefers the acoustic codes because it’s the easiest way to rehearse. STM can use visual codes also.
• Loss: How do we lose information out of STM? The debate about loss in STM has 2 competing possibilities. One possibility is the idea of decay-information simply deteriorates over time. This happens in the sensory register. Does it also happen in STM? A second possibility is referred to as displacement- when new information comes in, if there isn’t an empty slot for the information to fill, something has to go. As new information comes in, old information is lost. Attention gets directed at different things. As attention gets refocused new cues are processed.
• Baddeley’s Model of Working Memory: a cognitive researcher- said that we have a number of subsystems. STS can be subdivided into different systems inside the box. All of them are contained there. He felt that you needed a separate system for something that allocates attention-the central executive- which has to make decisions of how resources are located.  2 systems are under it. The first system is the Visual Sketch Pad: it allows you to do the visual cues and the mental rotation tasks. The other subdivision is the auditory loop. It takes on information and creates a verbal code and allows you to repeat it over and over again. It allows you to do the complete set until you’re done functioning with it.

March 9, 2006
 

• The transfer of information from STS to LTS: there are 2 processes or types of rehearsal that can lead to the transfer of information from ST to LT.
• The 1st type of rehearsal is maintenance rehearsal: not directly designed as a method of transfer from ST ot LT. IT will do it, but it’s a side effect. It is designed to maintain information in STS. It keeps the information alive for an extended period, and then it goes in to LTS. Its repetition of information, by doing this, is kept alive in STS. Its extended stay jams in LTS. For some kinds of information, it may be the only thing you can do.
• The more elegant and effective type of rehearsal is elaborative rehearsal. It is the process of taking information that is currently in STS and semantically (meaningfully) associating it with information already in LTS.
• The transfer always involves the 2 types of rehearsal.
• Capacity of LTS: unknown. The capacity may be unlimited- there is no evidence that you can’t keep putting new things into LTS.
• Duration of LTS: varies. LTS by definition is holding things for an extended period of time that is measured in hours, days, months, years and maybe decades or a lifetime. It depends on the nature of information and assumes that the brain is healthy. Some of the best studies looking at very LTM looked at retrieval of information after very many decades. They took someone who is older (50’-70’s) and asked them about childhood or high school days. They had a way of verifying this information by going through a yearbook. They were asked to write down the names of people from their graduating high school class-they may be able to remember 20 names. If you showed them their yearbook and if they haven’t been studying it and the names are block and all they see is faces- typically, the names will come rushing back to them. This indicates that very old memories are often still there and are accessible but as time passes, the kinds of cues necessary to extract information becomes more elaborate. They need more support of cuing from the environment. The studies are at least 50 years old. As information sets in LTM and is unused, the amount of cues needed increases.
• Representation: information is represented semantically (meaningfully). It always wants the interpretation of something. If you want to remember things, you have to extract meanings out of things and ask yourself their importance and pay attention to them. Then it is put in a form that LTS can use.
• “Loss”: controversial issued- it is the source of discussion among memory researchers. There are 2 competing hypotheses. One hypothesis is the idea of decay: information deteriorates over time. It will deteriorate if you don’t use it that much. The other hypothesis is retrieval failure: something is still there, but you fail to retrieve it. Usually there’s retrieval failure because some other bit of information is blocking access from what you’re tying to get to.
• The most well known study was done in the 20’s by Jenkins and Dallenback: there were 2 groups of subjects- both groups were required to learn a list of words. The difference was that one group it to learn the words immediately before going to bed. Over the course of the night, at 2 hour intervals, the experimenter wakes them up to test their memory on the words. The 2nd group of subjects is going to learn the same group of words but is going to lean them the 1st thing in the morning. They can leave and continue on their daily business but they have to come back every 2 hours. The argument was that if decay is the primary reason memory is lost through LTS then we ought to see equal performance out of the 2 groups because they are tested on the same time schedule.
• Interference or intervention: argued that there is a big difference between the day and night group. It causes trouble with the access to the words because they used different cues. The night time crew- showed a significant difference.
• Results of the study: there are significant results between the groups. The night time is always better. Some kind of retrieval failure was always found in the studies and their studies showed the same results.
• 2 types of interference: 1. retroactive interference: when newer information blocks access to older information, the time passing is: Time 1-one bit of information. Time 2- More information. Recall time- trying to remember A and B blocks access to it. What’s learned later blocks access to something learned earlier. EX: trying to remember the name of your 2nd grade teacher. When you’re trying to get to the name, the names of other teachers are blocking access to it. Something that is related to the target bit of information is what is blocking to information from being accessible. The closer the relationship, the more likely the interference effects. LTM is organized by meaning and is not randomly organized.
• Proactive interference is the second type of interference. It is when the older learning blocks access to newer learning. Time 1: A. Time 2: B. You are tying to remember B, but it’s the older thing, A, blocking access to it. EX: calling your new boyfriend by your old boyfriend’s name.
• Both types of interference can operate at the same time. You can get the whammy from either and this is the main sources of forgetting things.