Coding of Memory

Acoustic coding - the sound of a stimulus.

Semantic coding - the meaning of the stimulus.

Research on coding


  • Acoustic coding in STM, semantic coding in LTM.


Artifical stimuli

  • Words listed had no personal significance.
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Capacity of Memory

Digit span

  • Jacobs (digit span): 9.3 digits, 7.3 letters.

Span of memory and chuncking

  • Miller: 7 +/- 2 span, putting items together extends STM capacity.


Lacking validity

  • Could be extraneous variables such as distractions.

Not so many chuncks

  • Cowan: estimated STM as about 4 chuncks.
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Duration of Memory

Short Term Memory (STM)

  • Peterson and Peterson: up to 18 seconds without rehearsal.

Long Term Memory (LTM)

  • Bahrick et al. (yearbooks): recognition of face 90% after 15 years, recall 60%. Recognition dropped to 70% ater 48 years.


Meaningless stumuli - Used consonant syllables.

Higher external validity - Meaningful real life memories, showed greater recall that LTM studies with meaningless materials (Shepards).

Evaluation extra

  • Peterson and Peterson may be displacement not decay.
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The Multi-Store Model of Memory

Sensory Register - Iconic and echoic stores with very brief duration, high-capacity. Transfer by attension.

STM - Limited capacity and duration stored. Mainly acoustic coding. Transfers to LTM by rehearsal.

LTM - Unlimited capacity and duration, permanent store. Mainly semantic. Created through maintenance rehearsal.


Supporting research evidence - Studies into coding, capacity and duration demonstrate differences between STM and LTM.

There is more than one type of STM - Studies of amnesia (e.g. KF) show different STMs for visual and auditory material.

There is more than one type of rehearsal - Elaborative rehearsal necessary for transfer to LTM, no maintenance rehearsal.

Evaluation extra

  • Artifical material.
  • There is more than one LTM.
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Types of Long Term Memory

Episodic memory - memory for events in our lives.

Semantic memory - memory for knowledge of the world, like a dictionary. Includes languages.

Procedural memory - memory for automatic and often skilled behaviour.


Clinical evidence - Clive Wearing and HM had damaged episodic memories but semantic ad procedural memories fine.

Neuroimagging evidence - Episodic and procedural memorie realled from different parts of the prefrontal cortex.

Real-life application - Training progamme for aults with mild cognitive impairments.

Evaluation extra

  • Problems with clinical evidence.
  • Three types of LTM or two?
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The Working Memory Model

Central executive (CE) - Co-ordinates slave systems and allocates resources, very limited storage.

Phonological loop (PL) - Auditory information - phonoogical store andarticulatory process (maintenance rehearsal).

Visuo-spatial sketchpad (VSS) - Visual information - visual cache (store) and inner scribe (spartial arrangement).

Episodic buffer (EB) - Intergrates processing of slave systems and records the order of events. Linked to LTM.


Clinical evidence - KF had poor auditory memory but good visual memory. Damaged PL bus VSS fine.

Dual task performance - Difficult to do two visual tasks at same time, but one visual and one verbal is OK (Baddeley et al.).

Lack of clarity over the CE - Not yet fully explained, probably has different components.

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Explanation for forgetting: Interference

Types of Interference

  • Proactive - old memories disrupt new ones.
  • Retroactive - new memories disrupt old ones.

Effects of similarity - McGeorch and McDonald: similar words created more interference.


Evidence from lab studies - Well-controlled studies show intereference effects.

Artifical materials - Lists of words are not like everyday memory, may overemphasise intereference as an explanation.

Real life studies - Baddeley and Hitch (rugby players) supported intereference.

Evaluation extra

  • Time between learning.
  • Interference effects may be overcome using cues.
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Explanation for forgetting: Retrieval Failure

Encoding specificity principle - Tulving: cues most effective if present at coding and at retrival.

Context-dependent forgetting - Godden and Baddeley (deep sea divers): recall better when external contexts matched.

State-dependent forgetting - Carter and Cassaday (anti-histamine): recall better when internal states are matched.


Supporting evidence - Wide range of support: Eysenck claims retrival failure is most important reason for LTM forgetting.

Questioning context effects - No forgetting unless contexts are very different, e.g. on land versus underwater (Baddeley).

Recall versus recognition - Absence of cues affects recall but not recognition.

Evaluation extra

  • Problems with the encoding specificity principle.
  • Real life application.
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Factors Affecting EWT: Misleading Information

Leading questions - Loftus and Palmer (car speed): estimates affected by leading questions (smashed versus contacted).

Why do leading questions affect EWT? - Response bias - no change to money. Substitution explanation supported by Loftus and Palmer and report of presence of glass.

Post-event discussion (PED) - Discussions with other contaminates eyewitnesses' memories. Gabbert et al. demonstrated effect, calling it memory conformity - information and normative social influence involved.


Useful real-life applications - Could help prevent miscarriabges of justice and change police interviewing.

Tasks are artifical - Watching film clips ignores the stress and anxiety associated with a real accident or crime.

Individual differences - Older people amy be less accurate because of own-age bias.

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Factors Affecting EWT: Anxiety

Anxiety has a negatice effect on recall - Johnson and Scott (weapon focus): high-anxiety knife condition led to less good recall. Tunnel theory of memory.

Anxiety has a positive effect on recall - Yuille and Cutshall (shooting): high anxiety associated with better recall when witnessing real crime.

Explaining the contradictory findings - Yerkes-Dodson law suggests both low and high anxiety lead to poor recall (Deffenbacher).


Weapon focus effect may not be relevant - Pickel (raw chicken) showed that it may be a surprise and therefore tell us nothing about effects of anxiety.

Field studies sometimes lack control - Researchers can't control what happens to witnesses between the crime and the interview.

There are ethical issues - Creating anxiety in lab studies may cause psychological harm.

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Cognitive Interview (CI)

  • Report everything - Include even unimportant details.
  • Reinstate the context - Picture the scene and recall how you felt. Context-dependent forgetting.
  • Reverse the order - Recall from the end and work backwards. Disrupt expectations.
  • Change perspective - Put yourself in the shoes of someone else present. Disrupt schema.
  • The enhanced cognitive interview (ECI) - Adds social dynamices , e.g. establishing eye contact.


CI is time-consuming - Takes longer and needs special training.

Some elements may be more valuable than others - Report everything and Reinstate the context used together produced best recall.

Support for the effectiveness of ECI - ECI consistently produces more accurate recall than standard interview.

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