STM- Limited duration, memories dissapear unless rehearsed. Peterson/Peterson 1959 with 24 students, consonant syllable and count backwards for different lenghs of time.
Findings-Participants remembered 90% with 3 second interval, and 2% with 18 second interval. Suggests STM duration is maximum 20 seconds (when rehearsal is prevented).
LTM- Potentially unlimited duration. Bahrick et al 1975 asked people 48 years on to identify faces from their high school year book, 70% accuracy. Free recall 60%15 years-->30% 49 years.
-Marsh et al 1997 suggested duration of STM=2 seconds.
-Nairne et al 1999 found items recalled after 96 seconds.
Peterson/Peterson-- only studying memory for syllables/words.-May be measuring displacement of syllables by numbers, rather than memory duration.- Low in population validity, +high in internal validity, repeated measures design.
Bahrick et al-+High mundane realism, -not generalised to other info.
Capacity and Encoding.
STM-'Miller's magic number 7'. Simon 1974 found people have better memory for shorter chunks.
Evaluation: Cowan 2001 suggested 4 chunks, supported by research on visual information. Individual differences eg Jacobs found differences between 8/19 year olds. Real world application eg in postcodes.
LTM- Potentially unlimited capacity.
Baddeley 1966 gave participants acoustically/semantically similar/dissimilar words. Difficulty remembering acoustically similar in STM, semantically similar in LTM.
Evaluation: Brandimote 1992 found visual coding used in STM if verbal rehearsal prevented. Nelson and Rothbart 1972 found evidence of acoustic encoding in LTM.
Multi-Store Memory Model-Shiffrin/Atkinson 1968.
Sensory Memory-Transferred to STM by attention.
STM- Decays unless maintenance rehearsal. May be displaced by new information.
LTM- STM to LTM by elaborative rehearsal.
Evidence: Serial position effect by Glanzer and Cunitz supports rehearsal ie primary effect.
Different areas of brain eg STM prefrontal cortex and LTM hippocampus.
Case studies eg HM hippocampus removed so could no longer from LTMs, suggests acts as gateway for permanent storage.
Evaluation of MSM.
Strenghs: Strong evidence of 3 seperate stores.
Predictions about memory.
Provides account of memory for structure and process.
Limitations: Supporting evidence lacks validity as mostly college students/demand characteristics.
Case study KF showed not unitary stores- Schachter suggested semantic, episodic, procedural memory and perceptual representation system memory eg Spiers 2001 studied amnesia patients and found procedural/perceptual intact but others not.
Ruchkin et al 2003 tested pseudo words and real words and found different brain activity for each, suggests STM recognised real more as it is part of the LTM.
Craik and Tulving 1975 suggested memory ffected more by depth of encoding than rehearsal.
Working Memory Model-Baddeley/Hitch 1974.
Central executive-directs attention/resources to tasks. Limited capacity. (Evidence-Bunge et al 2000 found higher brain activity when doing dual task, shows increased attential demands).
Phonological loop- articulatory process for words heard/seen, looped in the ear as maintenance rehearsul. Phonological store for heard words ie acts as inner ear. (Evidence-explains word lengh effect eg phonological loop only rehearses short words).
Visuo spatial sketchpad-when planning spatial task. Logie 1995 suggested visual cache/inner scribe.(Evidence-did visual task while doing another visual (hard) or verbal (easy as 2 slave systems).
Episodic buffer-general store. Limited capacity. (Evidence-In immediate recall participants recalled sentences better than un-related words, shows episodic draws on LTM to link words).
General evidence: Case studies eg KF brain damage restricted to phonological loop as verbal/visual problems lesser than auditory.
Evaluation of WMM.
Strenghs: Explains psychological observations eg case studies/ word-lengh effect.
Real world applicability eg working memory has role in identifying schozophrenia.
Emphasises process more than MSM.
Limitations: Vague explanation of central executive. Eslinger and Damasio suggested more than 1 central executive due to case study EVR.
Evidence from brain damaged patients is inconclusive as we do not know situation before ie cause/effect.
EWT-Use of eyewitnesses in court to identify someone who has committed a crime.
Loftus and Palmer 1974: Experiment 1- 45 students shown films of traffic accidents+questionnaire with critical question 'how fast were the cars going when they ____ eachother' with verbs eg 'smashed, contacted, hit'. Results- 'smashed' average 41mph, 'contacted' average 30mph.
Experiment 2- New set of participants into 3 groups+shown traffic film. Given question about speed-group 1 'smashed' group 2 'hit' group 3 control so no speed question. After 1 week asked critical question about broken glass. Results-group 1 =16 said glass, group 2=7 and control= 6.
Evaluation: +Real world application in jury system.
-Males/females similar accuracy but older more prone to misleading information as cannot remember source of their information in comparison to young.
-Yuille and Cutshall 1986 interviewed 13 people 4 months after armed robbery. Despite 2 misleading questions there was high accuracy.
- Experiment low in ecological validity as does not represent real life eg anxiety of car crash.
Factors of EWT.
Anxiety: Christianson and Hubinette 1993 found from 58 real witnesses of bank robberies that those who had been threatened had more accurate recall (postitive effect). Deffenbacher 2004 met analysis of 18 studies, found high stress had negative impact on EWT accuracy. (Negative). Weapon-focus effect Loftus experiment condition 1 argument/pen had 49% accuracy at identification, condition 2 with bigger argument/knife had 33% accuracy.
Evaluation: Contradiction in research findings explained by Yerkes Dodson law (curve). Research eg Loftus et al 1987 found weapon physically pulls attention away from person's face. Real world application eg Titanic surviviors accurate in recall of boat splitting apart.
Age of witness: Parker and Carranza 1989 found children had higher rate of choosing than adults+more errors than college students. Yarmey 1993 stopped 651 adults and asked to recall details of woman, differences in confidence yet no significant difference in accuracy. Memon et al 2003 short delay no difference, delay of 1 week old were less accurate.
Evaluation: Individual differences eg intoxicated have lower accuracy. Differential experiece hypothesis explains why people better at identifying those of a similar age. Anastasi and Rhodes 2006 found young/middle aged more accurate and all groups identified accurately from own age group.
Orignial interview technique-( By Fisher and Geiselman 1992). Report everything (every detail even if irrelevant);Mental reinstatement of original context (mentally recreate environment); Changing the order (alternative ways through timeline eg reverse); Changing the perspective (eg how it appeared to other witnesses).
Evaluation: Meta-analysis of 53 studies found increased 34% accuracy with CI technique in comparison to standard techniques (yet most studies used volunteer witnesses in the lab).
Real world application by Stein and Memon in developing country Brazil 2006- CI produced much greater forensic accuracy than old methods of torture etc.
CI good in older witnesses as importance of reporting any detail so negative stereotypes lesser.
CI requires lots of time, not necessarily available.
Interviewer is required to be trained in CI techniques.
CI technique uses many stages so many organisations have different processes, yet claim CI.
Memory Improvement Strategies.
Techniques: Verbal mnemonics eg acronym, acrostic, rhyme, chunking. Visual imagery mnemonics eg method of loci, keyword method (Atkinson and Raugh 1975), spider diagrams/mindmaps. Colours etc gives information disinctive visual appearance.
Evaluation: Real world applicability eg Broadly and Macdonald 1993 memory techniques for students with down syndrome showed improvement.
Gruneberg 1973 folund 30% of psychology students used mnemonics in revision., shows popularity.
O'Hara et al 2007-training in mnemonic techniques eg method of loci had long-term memory benefits. However Slavin 2005 showed although mnemonics such as rhyming are useful in real life classrooms for remembering foreign vocabulary, they do not help with fluency of language.
Bower et al 1969 showed recall of words in hierarchy X2/3 better than in random order.
Mnemonic techniques help in elaboration, acts as rehearsal.
Paivio 1971 suggested dua-coding process. Therefore coding in pictures/words=X2.