memory

• the multistore model of memory (MSM)


  Atkinson & Shiffrin’s (1968, 1971) multi-store model describes how

  information flows through the memory system. The model suggests that memory is made up of three stores linked by processing.

  
• the multi-store model is a structural model proposed by Atkinson and shiffron 1968 which suggests we have 3 separate stores in memory. these stores differ in terms of coding (the way the info is represented), duration (how long the info lasts) and capacity (how much can be fitted in at one time. it is an example of an information processing model because it suggests that info flows through this sequence of stages
• the first stage is registering new information in sensory memory. there is a different store for each sense eg the iconic memory for vision and echoic memory for sounds. this lasts a very short time - no longer than a few seconds. as a consequnce a lot of info is lost before its transferred to the next stage, the short term memory. this holds approximately 7+-2 chunks of info - these are bits of info such as related words or catagories of images.
• the amount which can be fitted into this store can be increased by chunking (eg storing related items as a single unit). items in this store last about 18 seconds unless they are rehearsed. this is a process of sub-vocal verbal repetition (eg it is auditory) and this is how information in this store is represented as a sound-based code. this process allows us to retain info for longer and is also responsible for transferring info to the third store, the long term memory. this stores huge amounts of info for a very long time, using a meaning-based semantic code.
• Memory is the ability of the mind to retain information.   the multi-store model (MSM), which breaks memory down into 3 components:

  • Sensory register
  • Short-term memory
  • Long-term memory

  Atkinson and Shiffrin (1968) devised the multi-store model (MSM) of memory. It is a cognitive approach that explains memory as information passing through a series of 3 storage systems: the sensory register, then short-term memory, and then long-term memory.
• Each of these storage systems has different features in terms of: coding, capacity, duration
• The first system of the MSM is the sensory register. It basically contains the immediate data that comes from the senses.

  • Information enters the sensory register coded in a raw and unfiltered format via sense organs such as the eyes and ears. This information is processed by dedicated stores – for example, visual information goes to the iconic store, whereas auditory information goes to the echoic store.
  • There is a lot of constantly changing information that passes through these stores, and so the sensory register has a very large capacity.
• • However, most information that passes the sensory register is very quickly forgotten, and so its duration is very short. Different sensory stores have different storage duration – for example, the iconic store retains visual data for around 500 milliseconds, whereas the auditory store can retain sounds for up to 2 seconds.
• If the individual pays attention to the information coming in via the sensory register, that information is passed on to the next storage system of the MSM – short-term memory – where it may be retained for longer.
• The second system of the MSM is short-term memory. It basically contains all the information that an individual is currently thinking about.

  • Select information is passed on from the sensory register in the same raw format. This information is then coded into a format that is more digestible for short-term memory. For example, the words ‘ice cream’ could be coded visually (e.g. imagining a picture of ice cream), acoustically (e.g. repeating the words ‘ice cream’), or semantically (e.g. thinking about the meaning of the words ‘ice cream’ as a sweet and cold dessert).
• • Research suggests short-term memory has a capacity for between 5 and 9 (7 ± 2) items. For example, Jacobs (1887) tested participants’ ability to remember strings of letters and numbers. On average, the participants could remember 7 letters before reaching capacity and 9 numbers. However, capacity can be increased by ‘chunking’ items into semantically similar groups.
• • For example, the alphanumeric sequence 193913CIAAQA contains 12 individual items (too many for short-term memory), but these items can be split into 4 chunks (e.g. 1939 = start of World War 2, 13 = unlucky, CIA = Central Intelligence Agency, AQA = the exam board) that are easier to retain. The duration of short-term memory is about 30 seconds. This can be extended, though, via rehearsal (i.e. repetition). For example, you might retain a shopping list in your short-term memory by repeating the various items out loud or in your mind.
• Extended rehearsal can transfer information from short-term memory to the next storage system of the MSM: long-term memory.
• Long-term memory lasts anywhere from more than 30 seconds to an entire lifetime. There are several different types of long-term memory (see below), but all long-term memories will have originally passed through both the sensory register and short-term memory.
• • Like short-term memory, long-term memory can be coded in many ways: visually, acoustically, olfactorily (smell), semantically, and so on.
  • Research suggests the capacity of long-term memory is very large, and no studies have been able to determine a limit to the number of long-term memories that can be stored. Although memories are often forgotten, this isn’t because the person has ran out of space for memories but is instead due to deterioration or interference.
• • The duration of long-term memory depends on how it is coded and what kind of memory it is (e.g. skills typically have longer duration than facts) but potentially lasts for a lifetime. For example, Bahrick et al (1975) found participants who were shown photos of ex-schoolfriends 48 years after leaving school could still remember 70% of the faces and 80% of the names.
• Once a long-term memory is stored, it can be retrieved and temporarily transferred to short term memory and manipulated (this retrieval process may also improve the duration of the memory). An example of retrieval would be remembering a pleasant experience from your childhood and thinking about how you felt that day.
• working memory model 


  The working memory model (WMM) was developed by Baddeley and Hitch (1974) and builds on the multi-store model – in particular, the MSM’s model of short-term memory. Rather than replacing the MSM, the WMM is better understood as a more detailed description of the MSM’s short-term memory component.
• Whereas the MSM describes short-term memory as a single store, the WMM divides short-term memory into 4 separate components: the central executive, phonological loop, visuo-spatial sketchpad, and the episodic buffer. These components serve different functions and hold different types of information, which are actively worked upon as the individual thinks.
• WMM

  
• The central executive is the component that filters and co-ordinates the various components of working memory. It process sensory information coded in all forms (auditory, visual, etc.) and directs this information to three slave systems: the phonological loop, the visuo-spatial sketchpad, and the episodic buffer. The central executive also receives information from these slave systems once it has been processed by them.
• The central executive has a fairly limited capacity. For example, Baddeley (1996) observed that participants struggled to perform two tasks (e.g. generating lists of random numbers and switching between pressing letters and numbers on a keyboard) simultaneously, and suggested this was because both tasks were competing for central executive resources.
• So, part of the role of the central executive is to co-ordinate its limited capacity. For example, the central executive may direct information required for driving to the visuo-spatial sketchpad, and information required for talking would be directed to the phonological loop – allowing a person to drive and talk simultaneously. The central executive is also responsible for switching attention to specific information sources that require attention.
• The phonological loop is the system that deals with information coded in auditory format. It has two sub-systems:

  • Phonological store: A short-term store that briefly retains words and the order they appeared in (sometimes called the inner ear)
  • Articulatory loop: Repeats (rehearses) words to keep them within the phonological loop (sometimes called the inner voice)

  Research suggests the capacity of the phonological loop is limited to how long words are rather than how many words there are. For example, one long word is more difficult to store in the phonological loop than three short words.
• The visuo-spatial sketchpad is the mind’s inner eye – it stores visual and spatial information. Information within the visuo-spatial sketchpad is coded as mental pictures.
• The episodic buffer is a temporary store for information coded in all forms.

  The original WMM did not include the episodic buffer. But because the central executive has no storage capacity, and the phonological loop and visuo-spatial sketchpad are only able to store and process specific types of information, the introduction of the episodic buffer in 2000 explains how people can combine and store general information from the various components of short- and long-term memory.
• For example, the working memory of a story will likely contain visual, semantic, and chronological information (i.e. the order of events). These different types of information would be combined in the episodic buffer to form a coherent story in short-term memory.
• The multi-store model of long-term memory (LTM) explains it as one single store. However, this is overly simplistic, as research suggests there are many different types of long-term memory.

  The main distinction is between explicit and implicit long-term memory. Explicit LTM is conscious and easy to put into words – for example remembering your first day at school (episodic), or a fact such as “Paris is the capital of France” (semantic). In contrast, implicit LTM is more subconscious and includes skills and abilities such as knowing how to ride a bike (procedural).
• long term memory

  
• episodic

  Episodic long-term memory covers the story of our lives – things like memories of specific events and the order they occurred in. For example, remembering your first day at school, or a holiday you went on a few years back, or some embarrassing memory of falling over are all examples of episodic long-term memory. It includes context, details of what happened, and the emotions felt.

  Strong emotions cause episodic memories to be coded more strongly. Similarly, if episodic memories are highly processed (for example by rehearsal/repetition) they will be coded more strongly.
• semantic


  Semantic long-term memory covers meaning, understanding, and general knowledge. Examples of semantic memory would be facts like “the Battle of Hastings was in 1066” and general understanding of concepts like dogs as 4-legged mammals that run around and bark.
• Procedural long-term memory covers how to do things – actions, skills, abilities, etc. For example, remembering how to juggle, ride a bicycle, or drive a car. We begin forming procedural memories from a young age – things like knowing how to walk and talk are learned and then stored as procedural memory.
• Although procedural memories are easy to act out, they are difficult/impossible to consciously explain in words. So, unlike semantic and episodic LTM, procedural memory is implicit. The fact that procedural memories do not require conscious thought means they can be recalled while simultaneously performing other cognitive activities – for example, trying to remember what the tallest mountain is (semantic, explicit) while walking along the road (procedural, implicit).
• explanations of forgetting


  Forgetting is the inability to remember memories. Although there are many explanations of forgetting, the A level psychology syllabus lists two specifically: Interference and retrieval failure due to absence of cues
• The first explanation of forgetting is interference. Interference is when existing information stored in memory disrupts recall, and can be either proactive or retroactive:
• proactive interference


  Proactive interference is when older information interferes with your ability to remember something newer. For example, you’re trying to remember the new login password you set but you keep thinking of your previous one.
• retroactive interference 


  Retroactive interference is the reverse of proactive interference: It’s when newer information gets disrupted by older information. For example, you’re trying to remember your home address from 10 years ago but you keep thinking of your home address from 2 years ago.
• The second explanation of forgetting is an absence of cues. This happens when information is stored in long-term memory but can’t be accessed because there is nothing to trigger the memory. Tulving and Thomson (1973) suggest that forgetting is more likely to occur when the context in which the memory is recalled is different from the context in which the memory was coded.
• Context-dependent failure


  Context-dependent failure is when the external environment does not provide the cues necessary to recall a memory. For example, you might be perfectly able to remember your bank card pin code when you have to type it in an ATM, but struggle to remember it when walking along a beach.
• state-dependent failure 


  State-dependent failure is when the internal environment during recall is different from the internal environment when the memory was coded. An example of a differing internal environment would be being sober vs. on drugs. For example, Darley et al (1973) observed that participants who forgot where they hid money while high on cannabis were more likely to remember where they hid that money once they got high again compared to when they were sober.