Memory

• Duration of SR is very brief: less than half a second.
• Capacity of SR is high (e.g. over one hundred million cells in one eye each storing data).
• Coding of SR depends on the sense- visual, auditory, etc.
• Little of what goes into the SR passes further into the memory system- needs attention to be paid to it.
• STM is a limited capacity and duration store.
• Duration of STM: about 18 to 30 seconds unless the information is rehearsed.
• Capacity of STM: between 5 to 9 items before some forgetting occurs.
• Coding of STM: acoustic.
• LTM is a permanent memory store.
• When we want to recall materials stored in LTM it has to be transferred back to STM by a process called retrieval.
• Duration of LTM: potentially up to a lifetime.
• Capacity of LTM: potentially unlimited.
• Coding of LTM: tends to be in term of meaning, e.g. semantic.
• Strength of MSM: supported by research showing STM and LTM are different:

  • Baddeley found we tend to mix up words that sound similar when using our STM but we mix up words that have similar meanings when we use our LTM.
  • Shows that coding in STM is acoustic, and in LTM it is semantic.
  • Supports the MSM's view that these two memory stores are separate and different.
• Limitation of the MSM: evidence suggests there is more than one type of STM:

  • Shallice & Warrington studied KF, a patient with amnesia. His STM for digits was poor when they read them out loud to him but his recall was much better when he read the digits himself.
  • MSM states there is only one type of STM but KF study suggests there must be one short-term store to process visual information and another to process auditory information.
  • Working memory model is a better explanation for this finding because it includes separate stores.
• Limitation of the MSM: it only explains one type of rehearsal:

  • Craik and Watkins argued there are 2 types of rehearsal- maintenance and elaborative. Maintenance is the one described in the MSM.
  • Elaborative rehearsal needed for long-term storage. This occurs when you link information to your existing knowledge, or process it.
  • Very serious limitation of the MSM because it is another finding that cannot be explained by this model.
• Limitation of the MSM: research studies supporting the MSM use artificial materials:

  • Researchers often asked participants to recall digits, letters and sometimes words. Peterson and Peterson even used consonant syllables that lack meaning.
  • In everyday life, we form memories related to all sorts of useful things- peoples faces, their names, facts, places etc.
  • Suggests the MSM lacks external validity. Research finding may reflect how memory works with meaningless material in lab testing, but does not reflect how memory mainly works in everyday life.
• Limitation of the MSM: oversimplifies LTM:

  • Lot of research evidence that LTM not a unitary store.
  • We have three different LTM stores (procedural, semantic and episodic)
  • Limited because it does not reflect these different types of LTM.
• episodic memory (LTM store)

  • stores events (episodes) from our lives
  • they are time stamped- you remember when they happened
  • involve several elements- people, places, objects and behaviours woven into one memory
  • you have to make a conscious effort to recall them
• semantic memory (LTM store)

  • stores our general knowledge of the world
  • semantic memories are not time-stamped, we do not remember when we first learned this knowledge
  • semantic knowledge less personal and more about the knowledge we all share
• procedural memory (LTM store)

  • stores memories for actions and skills (e.g. driving a car)
  • recall occurs without awareness or effort
  • we may find these hard to explain (not declarative) because we recall these memories without conscious awareness
• strength of episodic memory: it is supported by case study evidence

  • clinical studies of amnesia (HM and Clive Wearing) showed both had difficulty recalling events that had happened to them in their pasts
  • but their semantic memories were relatively unaffected (e.g. HM did not recall stroking a dog half an hour earlier, but he did not need the concept of 'dog' explaining to him)
  • this supports the view that there are different memory stores in LTM because one store can be damaged but the others left unaffected
• strength of different LTM stores: brain scan studies show that there are different LTM stores

  • tulving et al. had participants perform various memory tasks while their brains were scanned with a PET scanner
  • episodic and semantic memories were in the prefrontal cortex; semantic in left side and episodic in right prefrontal cortex
  • this shows a physical reality in the brain to the different types of LTM, confirmed in many research studies, supporting its validity
• strength of different LTM stores: identifying different LTM stores has real-life applications

  • psychologists can target certain kinds of memory in order to improve people's lives
  • belleville et al. found that episodic memories can be improved in older people with mild cognitive impairments. training led to improvements (compared to control group)
  • this highlights the benefit of distinguishing between different types of LTM- it allows specific treatments to be developed
• limitation of the types of LTM: there are problems with clinical evidence

  • evidence is often based on clinical cases (e.g. HM and clive wearing) about what happens when memory is damaged
  • there is a serious lack of control of different variables in these studies (e.g. cannot control the precise location of the brain damage or personality variables)
  • so it is difficult to generalise from these case studies to determine the exact nature of LTM
• limitation of tulving's approach (types of LTM): there may only be two types of LTM

  • cohen and squire argued that episodic and semantic memories are stores together in one LTM store called declarative memory (memories that can be consciously recalled)
  • cohen and squire agree that procedural memory is a distinctly different kind of memory to semantic/episodic, and call it non-declarative
  • it is important to get the distinction between semantic and episodic memories right because the way we define them influences how memory studies are conducted
• the working memory model (WMM) was theorised by baddeley and hitch
• WMM is a model of STM

  • an explanation of how STM is organised and how it functions
  • for example, WMM is concerned with the part of the mind that is active when working on an arithmetic problem or playing chess or comprehending language, etc
• central executive (CE) allocates slave systems

  • essentially an attentional process which monitors incoming data and allocates slave systems to tasks
  • it has a very limited storage capacity
• phonological loop (PL) consists of two components

  • PL deals with auditory information and preserves the order in which the information arrives. it is subdivided into:
  • phonological store: stores the words you hear
  • articulatory process: allows maintenance rehearsal
• visuo-spatial sketchpad (VSS)

  • stores visual and/or spatial information when required, e.g. recalling how many windows your house has
  • logie subdivided the VSS into:
  • visual cache: stores visual data
  • inner scribe: records arrangement of objects in the visual field
• episodic buffer (EB)

  • a temporary store for information
  • integrates visual, spatial, and verbal information from other stores
  • maintains sense of time sequencing- recording events (episodes) that are happening
  • links to LTM
• strength of the WMM: the case of KF supports different STM stores

  • shallice and warrington carried out a case study of patient KF who had brain damage. he had poor STM ability for verbal information but could process visual information normally
  • so his phonological loop had been damaged but other areas of memory were intact. this suggests there are separate visual and acoustic stores
  • however, evidence from brain-damaged patients may be unreliable because it concerns unique cases of patients who have had traumatic experiences
• strength of the WMM: dual task performance studies support the VSS

  • baddeley et al. found participants had more difficulty doing two visual tasks (tracking a light and describing the letter F) than doing a visual and verbal task at the same time
  • the greater difficulty is because both visual tasks compete for the same resources. when doing a verbal and visual task simultaneously, there is no competition
  • therefore dual task performance activity provides evidence for the existence of the visuo-spatial sketchpad. the MSM cant explain this
• limitation of the WMM: lack of clarity over the central executive

  • cognitive psychologists suggest that the CE is unsatisfactory and doesn't really explain anything
  • the CE should be more than just being simply 'attention'. some psychologists believe it may consist of separate components
  • this means that the WMM hasn't been fully explained
• strength of the WMM: word length effect supports the phonological loop

  • baddeley et al. found people have more difficulty remembering a list of long words than short words. this is the word length effect
  • this is because there is limited space for rehearsal in the articulatory process (probably about two seconds)
  • word length effect disappears is a person is given a repetitive task typing up the articulatory process, demonstrating the process at work
• strength of the WMM: support from brain scanning studies

  • braver et al.'s participants did tasks involving the CE while they were having a brain scan. activity seen in an area known as the prefrontal cortex
  • activity in this area increased as the task became harder. this makes sense in terms of the WMM: as demands on the CE increase, it has to work harder to fulfil its function
  • so this study provides evidence that the CE may have a physical reality in the brain
• interference is when two pieces of information are in conflict
• interference theory states that forgetting occurs in LTM because we can't get access to memories even though they are available
• proactive interference- old interferes with new

  • occurs when an older memory disrupts a newer one