- Created by: BreeFRANCiiS
- Created on: 30-03-17 20:07
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.
- Words listed had no personal significance.
Capacity of Memory
- Jacobs (digit span): 9.3 digits, 7.3 letters.
Span of memory and chuncking
- Miller: 7 +/- 2 span, putting items together extends STM capacity.
- Could be extraneous variables such as distractions.
Not so many chuncks
- Cowan: estimated STM as about 4 chuncks.
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).
- Peterson and Peterson may be displacement not decay.
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.
- Artifical material.
- There is more than one LTM.
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.
- Problems with clinical evidence.
- Three types of LTM or two?
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.
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.
- Time between learning.
- Interference effects may be overcome using cues.
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.
- Problems with the encoding specificity principle.
- Real life application.
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.
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.
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.