Models of memory

Models of memory

1. The Multi-Store Model of Memory (Atkinson and Shiffrin)

   • The multi-store model proposes that memory consists of three stores - the sensory register, the short term memory (STM) and long term memory (LTM) and is linked by processing.
   • It describes how information is transferred through the stores, to become a memory how it is remembered and how it is forgotten.
   • Process
     • 1. The information from our environment initially goes to our sensory register. If you pay attention to this information it will go to your short term memory. If not, it disappears through decay.
     • 2. If the information in our short term memory is rehearsed (processed further) then it can be transferred to the long term memory. Here it remains forever but can be difficult to retrieve (retrieval failure).
     • Decay: Information that is not rehearsed disappears as time passes.
     • Displacement: Information being held in the STM that has been pushed out (displaced) by other information
   • Strengths
     • Primary - recency effect suggests STM and LTM exist and are seperate
       • Murdock - Asked participants to read a lost list of words and recall them in order. He found the words near the beginning and the end of the list were recalled but relatively few in the middle.
         • Primary effect: The words at the beginning of the list were able to be recalled as they would have had more time to be rehearsed and therefore transfer into the LTM store.
         • Recency effect: The words at the end of the list would be able to be recalled as these would still be in the STM by the end of the experiment (if tested immediately after)
         • The words in the middle of the list, if not rehearsed, would be displaced by the new words at the end of the list.
     • Baddeley's research into acoustic and semantic coing suggest STM and LTM are separate as they use different coding
       • Baddeley - Participants were asked to recall a list of 5 words in a series from the following categories: acoustically similar/dissimilar and semantically similar/dissimilar. The LTM study extended the list to 20 words which they had to recall after an interval of 20 minutes. He found that similar sounding words are harder to recall than dissimilar words (STM). And, for the LTM test, words that mean the same are harder to recall than semantically dissimilar words.
         • Suggests that STM is acoustically coded and the LTM is semantically coded. Therefore, there must be separate stores which supports the multi-store model.
   • Weaknesses
     • Rehearsal is not always needed for information to be stored in the LTM
       • In real life people don't spend time rehearsing information, yet is still transfers to the long term memory. Rehearsal is not always needed for memories to be stored and some items can't be rehearsed ie. smells
     • Some argue the multi-store model is oversimplified.
       • It assumes there is only one LTM store and on STM store however there could be more than one. This has been proved by evidence from brain damaged patients suggesting there is more than one STM store.
       • One considers rehearsal as a factor affecting the storage of information and not any others ie. chunking.

2. The Working Memory Model (Baddeley and Hitch)

   • As the multi-store model was criticised for being too simple, Baddeley and Hitch designed a new model for the STM. It proposes that, rather than being a single store, it is an active processor that contains several different stores.
   • Central executive (CE)
     • The 'boss' control - Co-ordinates all activities of the three slave stores (decides which store the information should be sent to to be processed)
     • Also, controls attention and plays a major role in planning and synthesises information. It has a limited capacity so can only attend to a limited number of information at once.
     • Visual-spatial sketchpad
       • Processes visual and spatial information. Responsible for setting up and manipulating mental images.
       • Often called the 'inner eye'
     • Episodic buffer
       • Brings together material from the other slave stores into chunks/episodes, providing a bridge between the STM and LTM. Most important role - Recalling material from the LTM and intergrating it into STM when it is required (recall).
       • Modification to the model by Baddeley in 2000
     • Phonological loop
       • Processes information in terms of sound (acoustic). This includes both written and spoken material. It stores a number of speech-based sounds for a brief time.
       • Phonological loop (inner ear) - acoustically coded items stored briefly here
       • Articulatory control (inner voice) - allows sub-vocal repetition of items stored in the phonological loop.
   • Strengths
     • Dual task performance supports the idea of separate slave systems.
       • Baddeley et al - Showed that participants doing two visual tasks (ie. tracking a light and describing the letter 'F') than doing both a visual and verbal task (tracking a light and doing a verbal task simultaneously). The increased difficultly is due to both visual tasks competing for the same slave store (visual-spatial sketchpad) whereas the phonological loop processes verbal tasks so there's no competition.
         • Supports the separate existence of the visual-spatial sketchpad as there must be a separate slave system that processes visual information to sound information.
     • Clinical evidence suggests the idea of separate visual and acoustic stores.
       • Shallice and Warrington - Studied patient KF who had suffered brain damage. He had poor STM ability for verbal information but could process visual information, suggesting only his phonological loop was damaged.
   • Weaknesses
     • Dual task performance experiments lack mundame realism
       • The tasks the participants were asked to carry out using this technique (performing 2 simultaneously) are often ones not encountered much in everyday life (ie. describing the letter 'F'). This lacks ecological validity.
     • Central exectutive is difficult to quantify
       • Little research has been done to understand the central executive so it's the least understood. This means the working memory model hasn't been fully explained.

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