Psychology AS (1)

Characteristics of memory: 

• Capacity; how much information our memories can hold
• Duration; how long our memories last
• Encoding; how information is changed so it can be stored

Types of memory:

• Short term memory (STM); memory for things that have just happened
• Long term memory (LTM); memory for things that have happened more than a few minutes ago

STM

• Capacity; 5 and 9 pieces
• Duration; 18 seconds
• Encoding; acoustic - based on how it sounds

LTM

• Capacity; limitless
• Duration; forever
• Encoding; semantic - based on it's meaning 

Jacobs 1887

Aim: demonstrate how much information can be stored in the STM

Method:

• serial digit span technique - presented with sequence of items (numbers/letters), asked to recall in the same order one by one. 
• used both numbers and letters, didn't use w or 7 as they have two syllables

Findings: 

• could recall digits more than letters 
• average of 9.3 digits and 7.3 letters
• recall increased with age

Conclusions: 

• STM has limited capacity
• easier to recall digits because there were only 9 digits but 25 letters
• capacity may increase with age or because of learning techniques

Strengths: 

• lab experiment; controlled
• metronome - ensured that all were read out at same pace
• reliable; Miller 1956

Limitations: 

• low ecological validity; artificial nature
• not representative of everyday tasks
• lacks temporal validity; findings may not be generalised to modern times (capacity unlikely to change)

Chunking; integrating information to make it meaningful

Pronunciation time; longer it takes to vocalise, harder to remember - Ellis and Henneley (1980); poorer capacity when tested using the serial digit span technique in Welsh

Individual differences; some people seem to have a larger STM capacity than others 

Harder to measure

Merkle 1998; looking at synapses in brain thought it to be 1000-1000000 gigabytes

Huang; memory for 560 students over more than two decades - could accurately recognise whether an individual was a past student or not on more than 50% of occasions 

Peterson and Peterson 1959

Aim: testing if duration was for around 18 seconds if rehearsal was prevented

Method: 

• 24 introductory psychology students given trigrams to recall 
• after hearing, asked to count backwards in threes from random numbers
• when red light showed, they recalled the trigram

Findings: 

• percentage recall after 3 seconds - 80%
• 6 seconds - 50%
• 18 seconds - less than 10%

Conclusions: 

• memory trace just disappears after 18 seconds
• supports hypothesis (18 seconds)
• STM is distinct from LTM (very different durations)

Strengths: 

• laboratory experiment; controlled
• could determine cause and effect
• reliable; Sebrechts el al 1989

Limitations:

• low in ecological validity; not a common occurrence to remember trigrams
• lacks population validity; all were students and small sample

Bahrick et al 1975

Aim: investigate duration of LTM

Method: 

• 392 American ex-high school students 17-74
• recall tested in four ways; free recall of classmates, photo recognition test (involved distractors), name recognition test, name and photo matching
• assessed by comparing responses with yearbooks

Findings: 

• percentage recall 90% face and name recognition after 34 years
• 80% accuracy name recognition after 48 years
• 40% accuracy face recognition after 48 years
• 30% accuracy free recall after 30 years

Conclusions: 

• classmates rarely forgotten when given recognition cues
• supports the claim that the LTM duration is very long
• supports the claim that recognition is better than recall
• demonstrates that LTM has a long duration for some but not all types of information

Strengths:

• reliable; Shepard 1967
• high ecological validity; field experiment (recalling high school friends is not artificial)

Limitations:

• poor control; was not recorded whether participants were still in contact with anyone from high school
• ungeneralisable; study only tells us about duration for high school memories
• lacks population validity; sample were all American

Rehearsal:

• maintenance rehearsal; repeating information over and over to hold it in our STM
• elaborative rehearsal; information is used and changed to store (usually in LTM)

Intention to recall; making a conscious effort to recall (Sebrechts et Al 1989) 

Nature of material to be learned; some types of material retained for longer (Conway et Al 1991)

Depth of learning; more likely to be remember for longer if learned very well (Bahrick and Hall 1991) 

Semantic; encoding on the basis of meaning

Acoustic; encoding according to how it sounds

Factors affecting Encoding

Age; research shows young people are more active when trying to encode information (make use of different strategies)

Nature of stimulus; research supports idea that words that are easy to picture are easier to remember than words that are not easy to picture 

Baddeley 1966

Aim: investigate encoding; whether acoustic or semantic are the preferred method

Method:

• presented with one of four word lists to remember
• each list was either acoustically similar, acoustically dissimilar, semantically similar, semantically dissimilar
• IV: whether the words were similar/dissimilar, DV: number of errors made
• STM participants asked to recall words immediately, LTM participants asked to recall the words after time delay

Findings:

• immediate recall found most confusion between acoustically similar words compared to the dissimilar but no difference in semantically similar or not 
• delayed recall found complete opposite

• in STM, words that sounded similar remembered least well
• in LTM, words that were remembered least well were the ones with similar meanings

Conclusions:

• STM encodes information based on how it sounds 
• LTM encodes information based on meaning

Strengths: 

• laboratory experiment; controlled
• could determine cause and effect
• reliable; Conrad 1964

Limitations:

• low in ecological validity; lab experiment - artificial
• doesn't consider types of encoding other than semantic and acoustic

Atkinson and Shiffrin 1968

memory is made up of three different stores

these three stores are completely separate from each other;

Sensory memory:

• registers everything our senses take in (everything we hear, see, smell and touch)
• only the iconic and echoic store have been specified
• iconic; sensory memory for visual material (only lasts for a fraction of a second)
• echoic; sensory memory for sound (duration is marginally longer than for the iconic store)

STM:

• uses acoustic encoding
• has a capacity of 5-9 pieces of information
• has a duration for around 18 seconds without rehearsal

LTM:

• uses semantic encoding
• has an unlimited capacity
• has an infinite duration

it specifies how information travels from one store to another;

Attention:

• for information to be passed from the sensory memory to the STM it should be paid attention to

Rehearsal:

• for information to stay in the STM for a short amount of time, it needs to be rehearsed - maintenance rehearsal
• for information to be transferred from the STM to the LTM it needs to be rehearsed - elaborative rehearsal (most effective way of transferring information)

• it states that the only way for information to be transferred into the LTM is through rehearsal

Strengths: 

• idea of STM and LTM being separate stores is supported by research evidence (Beardsley 1997)
• clinical studies of amnesiacs support idea that they are separate stores - people with amnesia lose either their STM or LTM (K.F)

Limitations:

• K.F's deficit in STM was only for verbal information (STM for visual material was normal) - suggests the existence of more than one type of STM
• notion of rehearsal is too vague - Bekerian and Baddeley 1980 (rehearsal is not the only way for information to be transferred into the LTM)

Baddeley and Hitch 1974

the concept of the STM should be replaced with that of working memory

working memory system has three components;

• a modality free central executive resembling attention
• a phonological loop holding information in phonological form
• a visuo-spatial sketchpad specified for spacial and/or visual encoding

as with the Multi-Store Model of Memory, it states that there are three separate stores;

Central Executive:

• key component of the working memory model
• involved in higher mental processes such as decision making
• allocates resources to phonological loop or visuo-spatial sketchpad depending on the task at hand
• limited capacity but very flexible - can process information from any of the senses

Phonological Loop:

 deals with speech based information

Articulatory Loop;

• verbal rehearsal loop that holds words 
• capacity of about 2 seconds
• known as 'inner voice'
• used to process words presented visually

Phonological Store;

• holds the words we hear
• known as inner ear
• used for words presented in speech based form

Visuo-Spatial Sketchpad:

deals with visual/spatial information

Visual Cache; stores information about visual form and colour

Inner Scribe; deals with spatial and movement information

Strengths: 

• research evidence supports that idea that the STM is made up of three different stores - Robbins et al 1996
• very influential model; moved away from the multi-store model's view of the STM being a unitary store

Limitations: 

• central executive is too vague - research suggests that it is not a unitary store (Elsinger and Damasio 1985)

legal term that refers to the use of eyewitnesses to give evidence in court concerning the identity of someone suspected of committing a crime

prior to the Devlin Report in 1976, it was generally assumed that EWT was sufficiently accurate to be used as sole evidence for prosecution

however, in 1976, the Devlin committee made the recommendation that no court should convict on the basis of EWT alone - specialists in the area know that EWT is unreliable

research has showed that not only are witnesses inaccurate in their memory of people and events, but there was little relationship between confidence and accuracy of recall and that accuracy of EWT is affected by factors such as age, anxiety and misleading information

Loftus and Palmer 1974

Aim: the effect of leading questions on the accuracy of EWT

Method: 

• 45 students shown 7 films of different traffic accidents
• after each film, they were asked to fill in a questionnaire with specific questions about the traffic accident
• one critical question; 'how fast were the cars going when they hit each other?' - given to one group
• other groups given the words 'smashed', 'collided', 'bumped', or 'contacted' in place of the word 'hit' 

Findings:

• the group given the word 'smashed' estimated a higher speed than the other groups 
• the group given the word 'contacted' estimated the lowest speed

Conclusions:

• the form of question can have a significant effect on a witness' answer
• leading questions can affect the accuracy of memory

Strengths: 

• reliable; other researchers have found that misleading information decreases the accuracy of EWT

Limitations: 

• very low in ecological validity - participants only watched videos of traffic accidents (the anxiety and arousal that a real life accident would cause would increase the accuracy of EWT - Yuille and Cutshall)

Loftus 1979

Aim: to investigate the effect of anxiety on the accuracy of EWT

Method: 

• volunteer sample used
• participants arrived at the university laboratory and asked to wait outside
• first condition (non anxiety) - participants overheard low key discussion about equipment failure then saw a man holding a pen with grease on his hands leave the laboratory
• second condition (anxiety) - participants overheard a heated and hostile exchange between people in the laboratory, after the sound of breaking glass and crashing chairs, a man emerged holding a bloody paper knife 
• participants were then given 50 photos and asked to identify the man

Findings:

• those in the non anxiety condition recognised the man 49% of the time
• those in the anxiety condition recognised the man 33% of the time

Conclusions: 

• anxiety produced by seeing a weapon decreases the accuracy of EWT
• thought to be because individuals focus their attention on the weapon rather than the perpetrator (weapon focus)

Limitations: 

• findings are unreliable - when studies have been carried out in real life situations, they have tended to find the opposite (Christianson and Hubinette 1993, Yuille and Cutshall 1986

these studies show that anxiety improves the accuracy of EWT

Anastasi and Rhodes 2006

Aim: to investigate the effect of age on the accuracy of EWT

Method: 

• 94 participants used 
• split into three groups (42 were 18-25, 20 were 35-45 and 32 were 55-78)
• participants show 24 photographs (of people from all three age groups) and asked to rate them for attractiveness
• later given 48 photographs and asked to identify which 24 they had seen previously (the other 24 acted as 'distractors')

Findings: 

• older participants had a slightly poorer recall than younger participants
• significantly found that there was an 'own age bias' - recall is best if the person in question is of the same age as yourself

Conclusions: 

• research demonstrates that when looking at the effect of age on the accuracy of EWT there are no black and white answers
• as well as considering the age of the eyewitness, the age of the perpetrator must be considered along with whether these ages 'match'

Strengths: 

• high degree of control - laboratory experiment

Limitations: 

• low population validity - all participants except for those in the older group were students (results may not apply to everyone)
• 'own age bias' may be found because of the nature of the participants (the students would have been surrounded by people of a similar age on a day to day basis)

research has found that questions asked during a police interview may distort an eyewitness' memory, and thus reduce its reliability

in the past, an eyewitness' account was repeatedly interrupted and the interruptions made it hard for the eyewitness to concentrate fully on the process of retrieval, and thus reduced recall

Geiselman et al 1985 

(developed the 'cognitive interview' - aims to improve the accuracy of EWT)

• the eyewitness tries to recreate the context existing at the time of the crime, including environmental and internal (e.g. mood state) information
• the eyewitness reports everything he or she can think of about the incident, even if information is fragmented
• the eyewitness reports the details of the incident in various orders
• the eyewitness reports the events from various perspectives

in the cognitive interview, there is no room for leading questions, therefore recall accuracy should be higher

Strengths: 

• research shows it is effective (Geiselman et al 1985)
• one of the most successful contributions to society made by cognitive psychologists (Geiselman and Fisher 1997)

Limitations: 

• very time consuming (Kebbell and Wagstaff 1996)
• only successful with regards to the recall of peripheral details as opposed to central details

they are not inherently connected to the material that has to be learned, but impose meaning and structure on material that is otherwise not very meaningful and structures

they typically involve adding something to the material to create meaningful associations between what is to be learned and what is already stored in the LTM

Method of loci: 

• when the items to be remembered are incorporated into a meaningful story which is then retold in order to remember them

Rhymes

Acrostics: 

• a verse in which the first letters correspond with the material that needs to be remembered

Strengths:

• research has shown mnemonics to be a successful strategy for memory improvement (Snowman et al 1980)

Limitations:

• loci is easier for lists of concrete nouns and is harder to apply to something which is abstract
• impractical

External Cues;

• cues in our environment that we can use to help us remember information
• being in the same environment as where you were when you first learnt the information can bring memories flooding back

Internal Cues;

• cues in our internal/bodily state
• to create the same internal state you were in when you learnt the information

Strengths:

• there is research which supports their effectiveness in aiding memory recall 

Limitations:

• impractical 
• limited to recalling factual information