Transcript Memory
MEMORY Unit 4 Psychology RAH INTRODUCTION Without memory, every moment would be a new experience. You would have no self-concept or personal identity, e.g. “Who am I?” Memory provides meaning to our lives by integrating the past, the present and enabling us to think about the future. Memory consists of a collection of complex interconnected systems, each of which serves a different purpose and operates in a very different way. We do not have a memory – we have different memory systems. INTRO CONT… Memory systems have some functions in common: Receive Process Store info for future use Human memory is not perfect. Perceptual systems are constantly bombarded with stimuli during our waking lives. The brain must select what information will be attended to, processed and stored in various memory systems. It must also decide what will be eliminated and therefore not stored in memory. This process is necessary or our systems would be overloaded. MEMORY AS AN INFORMATION PROCESSING SYSTEM Most psychologists view memory as an active information-processing system that receives, organises, stores and recovers information. Comparable to how a computer processes information. Like a computer, memory does not passively receive and store new information. Instead, it actively alters and organises incoming information so that it can be stored in a way that is relatively easily retrieved. Computers and human memory are also comparable because they each deal with information in a sequence involving three key processes: The encoding of information into a useable form Its storage or retention after being encoded Its retrieval or recovery when needed. ENCODING Information that is received and stored in memory must be converted from its raw sensory state to a form that the brain can process and use. New info must be placed or represented in some form (sound, visual etc) in the memory system. The entire process of CONVERTING information into a useable form or code that can be stored in memory is called encoding. STORAGE Next, info must be retained (kept) by the IPS. Storage is the retention of information over time. Human memory stores info in the brain. RETRIEVAL Lastly, info is retrieved and taken out of storage, when it is needed. Retrieval is the process of locating and recovering the stored information from memory so that we are consciously aware of it. Some info is easy to retrieve, e.g. birth date. Other info is harder to retrieve and we rely on cues to retrieve information that has been stored in memory. When human memory works effectively, encoding leads to storage and storage enables retrieval. ENCODING, STORAGE AND RETRIEVAL Incoming sensory information Encoding Storage Retrieval Information is converted for storage Information is retained in memory Information is recovered from memory when needed *If any one of these processes fail, information will not be remembered. MEASURES OF RETENTION How can you find out whether information has been retained in memory? Research findings suggest that the amount of information that will be retrieved from memory is, at least partly, dependent on the type of retrieval questions asked. 3 main kinds of measures used to determine how much information has been retained: recall, recognition and relearning. RECALL Recall involves being asked to reproduce information with the fewest possible cues to assist retrieval. Free recall is involved when participants are simply asked to remember as much information as they can, in no particular order. Serial recall is being ask to remember information in the order you learned it. During recall, you use a general cue to retrieve info, however, it does not always provide enough of a hint for you. Therefore, the more specific the cue, the more likely you are to locate and retrieve the relevant, correct information stored in you long term memory. Cued recall makes use of more specific cues to aid retrieval. RECOGNITION Recognition involves indentifying the correct information from among alternatives. We generally retrieve more information with this method, as we are provided with more cues or prompts. You can typically recognise more than you can recall. E.g. Multiple choice True/false A list of alternatives is provided. RELEARNING Relearning (method of savings), involves learning info again that has been previously learned and stored in long-term memory. If info is learned more quickly the 2nd time, it’s assumed that there must be some info retained from the 1st learning experience. Learning is considered the most sensitive of the 3 measures of retention. Relearning takes less time than it did originally to learn. It’s also called method of savings as it can be used to measure the amount of info ‘saved’ from previous learning. SAVINGS ARE CALCULATED BY: Savings = (no. of trials for original learning) – (no. of trials for relearning) (no. of trials for original learning) x 100 1 A savings score can also be calculated on the basis of the time taken to relearn information. (time for original learning) – (time for relearning) x 100 (time for original learning) 1 HERMAN EBBINGHAUS German psychologist, Ebbinghaus (1885) was the 1st researcher to scientifically study relearning. He memorised nonsense syllables such as jax, qir and kuv. These syllables are used in memory research instead of words so retention is not affected by the words having some sort of meaning with others words already in memory. Ebbinghaus found that even if he could not remember a single item from the original list, he could relearn the list much more quickly a 2nd time than he had learned it originally. He assumed that some info had been retained from the initial learning. Nonsense syllables consist of 2 consonants and 1 vowel in between. They are pronounceable, but have no meaning. RELATIVE SENSITIVITY OF MEASURES OF RETENTION The sensitivity of a measure of retention refers to its ability to assess the amount of info that has been stored in memory. Evidence indicates that: Recall is least sensitive Relearning most sensitive Recognition in between Read through experiment on page 335 of textbook. STAGES OF MEMORY The Information Processing Approach to memory has 2 key features: 1. that mental processes such as memory can be best understood by comparing them with the workings of a computer. 2. that memory processes can be explained in terms of info progressing through a series of separate stages, one step at a time, but not necessarily in one directions. The information processing model of memory proposed by Richard Atkinson & Richard Shiffrin (1968), sometimes called the modal model or the stage model for memory, provides a broad framework that is useful in explaining the basic workings of memory. THE ATKINSON-SHIFFRIN MODEL Describes human memory as consisting of 3 distinguishable kinds of memory. Each 1 representing a stage through which info passes in a sequential way. When info is received from the environment, it passes from sensory memory to short-term memory and then to long-term memory. Info may also pass back from long-term memory to short-term memroy. Each stage differs in terms of its function, its capacity and its duration. SENSORY MEMORY All information, whether you pay attention to it or not, is temporarily held in sensory memory. Sensory memory is the entry point for new information into the memory system. Info is not encoded SM has the capacity to store all sensory experiences (briefly) & therefore it is assumed to be unlimited in capacity. Stores sensory impressions long enough so that they over lap. Thus world is perceived as continuous. We attend to and select the info to be transferred to short term memory (STM). If sensory info is not attended to and nor further processing (encoding) occurs, it fades & cannot be transferred to STM. ICONIC MEMORY Incoming sensory info is stored in separate subsystems called sensory registers. Iconic memory is the name given to visual sensory memory, or the memory of visual sensory info. Each new image is registered in iconic memory before the previous image fades, hence you are able to ‘see’ the entire image. Close your eyes for one minute. Near the end of the minute, hold your hand about 25 centimetres in front of your eyes. Then open you eyes and rapidly close them again. What do you see? GEORGE SPERLING (1960) Demonstrated existence of a sensory register for visual sensory information. He used a tachistoscope to present participants with sets of 12 letters arranged in a pattern and participants had to write down as many as they could recall. Most could recall only 4 or 5. In such short exposure only , reporting all letters was impossible. Participants reported they remembered seeing the letters, but by the time they had to write them, they had faded from memory. So to test that all letter remained in iconic memory, he conducted a further experiment in which he sounded a tone just after a pattern of letters. Each tone had to do with a row & participants were able to better recall the letters. Results indicate that an image of all the letters had been momentarily stored in the iconic memory after pattern left the screen. ECHOIC MEMORY Echoic memory is the name given to auditory sensory memory, because sounds linger like an echo. Processes all kinds of sounds. It stores sounds in their original sensory form. The main difference between iconic & echoic memory seems to be the length of time it takes info to fade. Echoic stores for typically 3-4 seconds and iconic for 0.3 seconds (approx.) Echoic memory stores the tail-end of the question temporarily while earlier parts of the message are being processed. This is important for understanding speech. Auditory info must be stored long enough for all the sounds involved to be received. SENSORY MEMORY CONCLUSION SM can store virtually all the info provided by our sensory receptors, yet, this info fades rapidly. It happens so quickly that that we are rarely aware of our capability for storing sensory info. SM may act as a filter to keep out irrelevant and unimportant info and prevent it from cluttering the sensory stores. When you attend to info in sensory memory, it is transferred to short-term memory. Only the info selected for transfer to short-term memory receives further processing and has a chance of being stored permanently. Info that is not attended to in SM is lost very quickly. SHORT-TERM MEMORY STM is a memory system with a limited storage capacity in which info is stored for a relatively short period of time (but longer than sensory memory). The info is an encoding(representation). Items in STM can be retained for the 1st few seconds. After approx 12 seconds, recall starts to decline and by about 18 seconds almost all of the info disappears entirely if it is not renewed in some way. Generally, most info is lost from STM after 20 seconds. Info can be reviewed and this retained in STM for longer periods of time through use or by consciously repeating it. STM temporarily holds all the info you are consciously thinking about at any moment of time. STM AS WORKING MEMORY Also known as working memory. Working memory is an active part of memory where info you are consciously aware of is actively ‘worked on’, thought about and processed. It works on info from sensory memory and long term memory (LTM). Imagining, problem solving, analysing, reasoning, comprehending and planning all involve working memory. When you mentally add the numbers 17+5+12, the info is temporarily held in working memory while it is being used or worked on. Thus working memory provides a temporary storage facility and ‘mental workspace’ for info currently being used in some conscious, cognitive activity. Once info has been used, it is either further processed and moved to LTM or discarded. ALLAN BADDELEY (1999) Proposed that working memory consists of 3 subsystems: 1. verbal info 2. visual info 3. a ‘central executive’ that does the work of processing info in the other 2 sub-systems. Verbal working memory (or phonological loop) stores a limited number of sounds for short period of time. Visual working memory (or visuospatial sketchpad) temporarily stores visual and spatial info, such as location. The central executive integrates info from the verbal and visual storage systems, as well as info retrieved from LTM. It’s also responsible for suppressing irrelevant info from our conscious thinking. The central executive plans & coordinates, but most psychologists believe it does not store info. ALLAN BADDELEY’S (1999) MODEL OF WORKING MEMORY Sensory Memory Working memory (STM) Phonological Loop Visuo-spatial sketch pad Central Executive Long Term Memory DURATION OF STM Info can be kept in STM for longer than the usual maximum of about 18-20 seconds by maintenance rehearsal. Psychologists Margaret & Lloyd Peterson (1959) conducted an experiment where participants were given trigrams to memorise. Participants where then given an interference task to prevent rehearsal of the trigrams. Following a time interval that varied from 3-18 seconds, a light was used as a signal for participants to recall the trigrams. The longer the interval, the less likely a participant was to accurately recall a trigram. CAPACITY OF STM STM is very limited in storage capacity. George Miller (1956) researched that STM has a capacity of holding between 5 & 9 units of info at any one time (published ‘The magical number 7, plus or minus 2’). Estimates are obtained by asking research participants to memorise simple lists of data of different lengths. The length of the list that the participants can recall half the time is considered to represent the capacity of STM. When STM is ‘full’, new items can only be added by pushing old items outs. Space in STM is also filled when we think and when information is temporarily brought from LTM into working memory to be used or updated. CAPACITY OF STM: DECAY & DISPLACEMENT Info stored in STM is lost primarily through decay & displacement. Decay of info (not being used) in STM occurs when you forget what you want to say in a conversation while you wait for the other person to finish speaking. Displacement of info (being pushed out) from STM was demonstrated in research in which participants called directory assistance for a long-distance telephone number. They showed poorer recall of the number if the person providing the info said ‘have a nice day’ after giving the number. Complete activities on page 347. ACTIVITY Read the sequence of letters below: D N V R C E W V DC S V Now close your eyes and try to repeat the letters aloud in the same order. Unless you have an exceptional STM, you probably could not repeat the whole sequence correctly. Now try this sequence of letters: NSW VCR VCE DVD Is it easier to remember than the first sequence? The increased ability to recall the second sequence demonstrates chunking. CHUNKING INFORMATION Chunking is the grouping or ‘packing’ of separate bits of info into a larger single unit or ‘chunk’ of info. Chunking can increase the amount of info held in STM. STM is a working memory system with limited capacity and duration in which info is lost rapidly unless rehearsed. The capacity of STM is about 7 chunks of info, but this amount can be increased by increasing the amount of info in each chunk. However, not matter how good a job we do of chunking and rehearsing, info must be transferred to LTM for more permanent storage. Thus, STM is used to work on new info or info retrieved from LTM, to select & process ongoing info & to store memories for a short duration. EFFECTS OF REHEARSAL Info can be kept in STM for longer than the usual maximum of about 20 seconds if it is rehearsed in some way. In the study of memory, rehearsal is the process of actively manipulating info so that it can be retained in memory. There are 2 main types of rehearsal – maintenance rehearsal and elaborative rehearsal. MAINTENANCE REHEARSAL Involves repeating the info being remembered over and over again to retain it in STM. It can be verbal (words) and non-verbal (visual). When it’s verbal, maintenance rehearsal can occur vocally or subvocally. Maintenance rehearsal does not always lead to long-term retention. Nonetheless, maintenance rehearsal is an important technique for coping with the limited during of STM. One drawback however is that when info is continually renewed in STM through rehearsal processes, the amount of new info that can enter is restricted because of the limited storage capacity of STM. ELABORATIVE REHEARSAL While maintenance rehearsal is an effective strategy for retaining information in STM, it does not assist in encoding info for transfer to LTM. Elaborative rehearsal is the process of linking new info in a meaningful way with info already stored in memory or with other new info, to aid in its storage and retrieval from LTM. Elaborative rehearsal is a more active process than maintenance rehearsal. It is also more effective than maintenance rehearsal for remembering info because it helps to ensure that info is encoded well. When we relate new info to personal experiences and our personal situation, encoding is enhanced and therefore we are more likely to remember it. This is called the self-reference effect. CONSOLIDATION THEORY Proposes that physical changes to the neurons in the brain occur when something new is being learned, and immediately following learning. These neuronal changes occur for a period of time after learning takes place, as the new info consolidates in memory. Also proposes that if memory is disrupted during the consolidation phase, info may be lost & not processed into LTM.