memory

Research on coding

Information is stored in memory in different forms depending on the memory store.

The process of converting information between different forms is called coding.

Alan Baddeley (1966) gave different lists of words to four groups of participants to remember:

Group 1: acoustically similar

Group 2: acoustically dissimilar

Group 3:semantically similar

Group 4: semantically dissimilar

Participants were shown the original words and asked to recall them in the correct order. When they did this task immediately, recalling from short-term memory, they tended to do worse with acoustically similar words.

When they recalled the word its after the time interval of 20 minutes, recalling from long-term memory, they did worse with semantically similar words.

These findings suggest information is coded acoustically in short-term memory and semantically in long term memory.

Research on coding strength- seperate memory stores

One strength of Baddeley’s study is that it identified a clear difference between two memory stores.

Later research showed that there are some exceptions to Baddeley’s findings.

But the idea that STM uses mostly acoustic coding and LTM uses mostly semantic coding has stood the test of time.

This was an important step in our understanding of the memory system, which led to the multi-store model.

Research on coding limitation-artificial stimuli

One limitation of Baddeley’s study was that it used quite artificial stimuli rather than meaningful material.

For example, the word lists had no personal meaning to participants.

So Baddeley’s findings may not tell us much about coding in different kinds of memory tasks, especially in everyday life.

When processing more meaningful information, people may use semantic codes even for short-term memory tasks.

This suggests that the findings from this study have limited application.

Research on capacity- digit span

Digit span

How much information can STM hold at one time.

Joseph Jacobs (1887) found out by measuring digit span; for example, a researcher reads out four digits, and the participants recall them out loud in the correct order.

If this is correct, the researcher reads out 5 five digits and so on until the participant can no longer recall the order correctly; this indicates the individual’s digit span.

Jacobs found that the mean span of digits across participants was 9.3 items and the mean span of letters was 7.3.

Research on capacity- span of memory and chunking

George Miller (1956) made observations of everyday practice.

The span of STM would be 7 plus or minus 2 items.

He also noted that people can recall five words as easily as they can recall five letters.

We do this by chunking- grouping sets of digits or letters into units or chunks.

Research on capacity strength- valid study

One strength of Jacobs’ study is that it has been replicated.

The study is a very old one, and early research in psychology often lacked adequate controls.

For example, some participants’ digit spans may have been underestimated because they got distracted during testing (an extraneous variable).

Despite this jacobs’ studies have been confirmed by better-controlled studies such as Bopp and Verhaeghen (2005).

This suggests that Jacobs’ study is a valid test of digit span in STM.

Research on capacity limitation- not so many chunks

One limitation of Millers research is that he may have overestimated STM capacity.

Nelson Cowan (2001) reviewed other research and concluded that STM capacity is only about 4 plus or minus one chunks.

This suggests that the lower end of Millers estimate (five items) is more appropriate than seven times.

Research on duration- duration of STM

Margeret and Lloyd Peterson (1959) tested 24 students in eight trials each.

on each trial the student was given a consonant syllable ( such as YCG) to remember.

Also given. three digit nuber.

Student count backwards from this number until told to stop, this was to prevent any mental rehearsal of the consonant syllable.

One each trial they were told to stop after varying periods of time: 3, 6, 9 ,12,15 or 18 seconds (the retention interval).

Findings has shown that after 3 seconds, 80% had remembered but after 18 seconds, only 3% remembered.

Petersons findings suggested that STM duration may be about 18 seconds unless we repeat information over and over.

Research on duration- duration of LTM

Harry Bahrick (1975)

studied 392 American participants aged between 17 and 74.

High school yearbooks were obtained from the participants or directly from some schools.

Recall was tested by:

Photo recognition test consisting of 50 photos, some from the participants’ high school yearbooks.

Free recall test where participants recalled all the names of their graduating class.

Participants tested within 15 years of graduation were about 90% accurate in photo recognition.

After 48 years, recall declined to 70% for photo recognition.

Free recall was less accurate than recognition- about 60% after 15 years, dropping to 30% after 48 years.

This shows that LTM may last up to a lifetime for some material.

Research on duration limitation- decay versus interference

One limitation of Peterson and Peterson’s study is that the result may be due to interference and not decay.

They concluded that forgetting of STM was due to the decay of memory traces over time.

However, it could also be due to interference from counting backwards.

This suggests that the conclusions about duration of STM may not be valid.

Research on duration strength- high external validity

One strength of Bahrick’s study is that it has high external validity.

This is because the researchers investigated meaningful memories.

When studies on LTM were conducted with meaningless pictures to be remembered, recall rates were lower (Shepard, 1967).

This suggests that Bahrick’s findings reflect a more “real” estimate of duration of LTM.

The multi-store model

Richard Atkinson and Richard Shiffrin (1968,1971) describe how information flows through the memory system.

The model suggests that memory is made up of three stores.

PHOTO

sensory register- MSM

All stimuli from the environment pass into the sensory register.

The part consists of sensory memory stores, one for each of our five senses.

Coding in each store is modality-specific.

Visual: iconic memory; acoustic information: echoic memory.

Duration of material in SR is very brief- about 0.05 seconds for iconic memory and 3 seconds for echoic memory.

SR has a very high capacity.

Information passes further into the memory system if you pay attention to it.

short term memory- msm

Information in the short-term memory is encoded mainly acoustically.

Lasts about 18 seconds unless rehearsed- temporary store.

STM is a limited-capacity store- only contains a certain number of things before forgetting occurs (7 plus or minus 2).

Maintenance rehearsal occurs when we repeat material to ourselves over and over again.

We can keep information in our STM as long as we rehearse it.

If rehearsal is long enough, it passes into long-term memory.

long term memory- msm

This is the potentially permanent memory store for information that has been rehearsed.

Coded mostly semantically.

Duration may be up to a lifetime.

Unlimited capacity.

Bahrick demonstrated that we are able to recognise the names and faces of school classmates almost 50 years after graduating.

When we want to recall information from LTM, it has to be transferred back into STM by a process called retrieval.

The MSM model strength- seperate roles + counterpoint

One strength of the MSM is support from research using modern techniques that still shows the STM and LTM are seperate stores.

Larry Squire (2009) reviewed neuroimaging studies that compared the brain areas associated with STM and LTM.

The prefrontal cortex is significantly active during tasks involving STM.

The hippocampus has been associated with the reorganisation and consolidation of memories during the lengthy period after learning (LTM).

These regional differences in the brain suggest that STM and LTM are independent stores, as claimed by MSM.

COUNTERPOINT

Charan Ranganath and Robert Blumenfeld (2005) suggest this may be an oversimplified view.

There is significant overlap and interaction between brain regions that support STM and LTM.

The hippocampus is also involved in STM tasks, particularly when it involves complex or new information.

This suggests that the evidence for a clear-cut separation between STM and LTM is not as strong as often assumed.

The MSM model limitation- more than one STM store

One limitation of the MSM is evidence of more than one STM store.

Shallice and Warrington (1970) studied KF, who developed amnesia as a result of being in a motorcycle accident.

KF’s STM for digits was very poor when read out loud to him.

However, his recall was much better when he read the digits to himself.

Studies of KF suggest there could be another short-term store for non-verbal sounds.

This evidence suggests that the MSM is wrong in claiming there is just one STM store processing different types of information.

The MSM model limitation- elaborative rehearsal

Another limitation of the MSM is that prolonged rehearsal is not needed to transfer to LTM.

According to the MSM, maintenance rehearsal means information is more likely to be transferred to LTM.

Craik and Watkinson (1973) found that the type of rehearsal is more important than the amount.

Elaborative rehearsal is needed for long-term storage.

This occurs when you link information to your existing knowledge, or you think about what it means.

This means information can be transferred to LTM without prolonged maintenance rehearsal.

This means MSM doesn’t fully explain how long-term storage is achieved.

The MSM model evaluation- model or framework

A criticism is that LTM, like STM, is not a single memory store.

Endel Tulving (1985) proposed that it could be subdivided into different types of LTM memory- e.g. semantic and episodic memory.

Cognitive psychology today focuses on these different types of memory and largely ignores MSM.

However, John Wixted (2024) argues psychologists have misunderstood the MSM.

It was never intended as a specific theory but rather a framework for incorporating our changing understanding of how memory works.

The working memory model

Explanation of how short-term memory is organised and how it functions.

STM is a dynamic processor of different types of information using subcomponents coordinated by a central decision-making system.

The WMM is concerned with the mental space that is active when we are temporarily storing and manipulating information.

The model consists of four main components, each of which is qualitatively different, especially in terms of coding and capacity.

WMM- central executive

The central executive monitors incoming data, focuses and divides our limited attention.

It allocates subsystems to tasks.

The CE has a limited processing capacity and does not store information.

WMM- phonological loop

Deals with acoustic information; coding is acoustic.

Subdivided into:

Phonological store- which stores the words you hear/read.

The articulatory process- which allows maintenance rehearsal; the capacity of this loop is believed to be two seconds’ worth of what you can say.

WMM- visuo-spatial sketchpad

The VSS stores visual and/or spatial information when required.

Has a limited capacity.

Baddeley (203) suggests the capacity is about 3 or 4 objects.

Robert Logie (1995) subdivides the VSS into:

The visual cache, which stores visual data.

The inner scribe, which records the arrangement of objects in the visual field.

WMM- episodic buffer

Added to the model by Bsaddeley in 2000.

Temporary store for information, integrating the visual, spatial and verbal information processed by other stores and maintaining a sense of time sequencing - recording events that are happening.

Can be seen as a storage component for the central executive

Baddeley (2012) has a limited capacity of about four chunks.

This episodic buffer links working memory to long-term memory and wider cognitive processes such as perception.

WMM strength- clincal evidence + counterpoint

One strength is support from Shallice and Warrington's (1970) case study of patient KF.

After KF’s brain injury, he had poor STM ability for acoustic information, but he could process visual information just as well as before his injury.

His immediate recall of letters and digits was better when he read them himself (visual) than when read to him (acoustic).

KF’s phonological loop was damaged, but his visuo-spatial sketchpad was intact.

This finding strongly supports the existence of seperate subsystems for visual and acoustic information.

COUNTERPOINT

However, it is unclear whether KF had other cognitive issues (besides damage to the phonological loop) which might have affected his performance on memory tasks.

His injury was caused by a motorcycle accident; the trauma involved may have affected his cognitive performance quite apart from any brain injury.

This challenges evidence that comes from clinical studies of people with brain injuries that may have affected many different systems.

WMM strength- neuroimaging evidence

A strength is evidence from brain scans for the existence of subsystems in working memory.

Smith and Jonides (1997) used PET to show that tasks using the phonological loop were linked with activation in the left temporal and frontal lobes.

Tasks using the visuo-spatial sketchpad were associated with activity in the right parietal lobe.

Tasks requiring the central executive were associated with widespread activation in the frontal cortex.

This study provides reliable and objective evidence for working memory subsystems.

WMM- nature of the central executive

One limitation is that there is a lack of clarity over the nature of the central executive.

Baddeley (2003) himself recognised this when he said:

The central executive is the most important but the least understood component of working memory”.

The CE needs to be more clearly specified than simply being “attention”.

Some psychologists believe the CE may consist of seperate subcomponents.

This means that the CE is an unsatisfactory component, and this challenges the integrity of WMM.

WMM evaluation- validity of model

Dual task performance supports WMM because two tasks that share a subsystem are much harder to perform together.

Therefore must be seperate components in working memory.

However, these studies use tasks that are very unlikely to be the tasks we perform in everyday life.

Studies were also conducted in highly controlled lab conditions.

Interference theory

Some forgetting takes place because of interference

This occurs when two pieces of information disrupt each other, resulting in forgetting of one or both or resulting in distortion of memory.

Interference has been proposed as an explanation of long-term memory.

Forgetting of LTM means we can’t access memories even though they are available.

Interference between memories makes it harder to locate them.

Types of interference

Proactive interference: occurs when an older memory interferes with a newer one.

Retroactive interference: occurs when a newer memory interferes with an older one.

Research on effects of similarity

In both PI and RI, the interference is worse when memories are similar.

John McGeoch and William McDonald (1931) studied retroactive interference by changing the amount of similarity between two sets of materials.

Participants had to learn a list of 10 words until they could remember them with 100% accuracy.

6 groups had to learn different types of new lists:

synonyms

antonyms

words unrelated to the original list

consonant syllables

three-digit numbers

no new list (control condition)

Findings:

When participants were asked to recall the original list of words, the most similar words produced the worst recall.

This shows interference is stronger when memories are similar.

Explanation of the effects of similarity

Similarity may affect recall for two reasons:

PI- previously stored information makes new similar information more difficult to store.

RI- new information overwrites previous similar memories because of the similarity.

Interference strength- real world application + counterpoint

One strength is that there is evidence of interference effects in more everyday situations.

Baddaley and Hitch (1977) asked rugby players to recall the names of teams they had played against during the rugby season.

Players all played for the same interval of the season, but some players missed matches due to injury.

Players who played most games (most interference) had the poorest recall.

This study shows that interference can operate in at least some real-world situations, increasing the validity of the theory.

COUNTERPOINT

Interference may cause some forgetting in everyday situations but it is unusual.

Conditions for interference to occur are rare.

This is unlike lab studies used to test interference (controlled conditions), which allow researchers to create ideal conditions for interference.

Two memories have to be fairly similar to interfere with each other; this may happen occasionally in everyday life but not often.

This suggests forgetting may be better explained by theories such as retrieval failure due to lack of cues.

Interference limitation- interference and cues

One limitation is that interference is temporary and can be overcome by using cues.

Tulving and Psotka (1971) gave participants lists of words which were organised into categories.

Recall averaged about 70% for the first list but became progressively worse as participants learned each additional list.

At the end of the procedure, participants were given a cued recall test- told names of categories- recall rose again to 70%.

This shows interference causes a temporary loss of accessibility to material that is still in long-term memory, a finding not predicted by interference theory.

Interference limitation- individual differences in interference effects

A limitation is that some people are more resistant to the effects of interference than others.

Edward Vogel (2005) gave participants a series of tasks to test their working memory capacity.

Highest and lowest scores were given additional tasks designed to create proactive interference.

Individuals with high WMC were much less likely to be affected by PI than low WMC individuals.

The researcher suggests high WMC is associated with enhanced filtering ability, which prevents irrelevant information from cluttering working memory.

So high WMC individuals are less susceptible to PI as they are more effective at maintaining focus on relevant information.

This suggests that interference is a limited explanation of forgetting, as it does not apply to all people.

Interference evaluation- validity issues

Most studies supporting interference are lab-based, so researchers control variables.

Control over extraneous variables means studies show a causal link between interference and forgetting.

But these studies use unrealistic procedures and artificial measures.

In everyday life, we often learn something and recall it much later; there is no interference.

Retrieval failure due to absence of cues

The reason people forget information may be due to insufficient cues.

When information is initially placed in memory, associated cues are stored at the same time.

If cues are not available at the time of recall, it may appear as if you have forgotten the information.

But this is actually due to retrieval failure- not being able to access memories that are there.

Encoding specificity principle

Endel Tulving (1983) reviewed research into retrieval failure and found a pattern known as the encoding specificity principle.

This states that a cue has to be both present at encoding and present at retrieval.

If cues available at encoding and retrieval are different, there will be some forgetting.

Some cues are encoded at the time of learning in a meaningful way.

Other cues are also encoded at the time but not in a meaningful way:

Context-dependent forgetting- recall depends on external cues.

State-dependent forgetting- recall depends on internal cues.

Research into context dependent forgetting

Godden and Baddeley (1975) studied deep-sea divers who work underwater to see if training on land helped or hindered their work underwater.

Divers learned a list of words either underwater or on land and were then asked to recall underwater or on land.

Findings:

Accurate recall was 32% lower than in non-matching conditions.

In non-matching conditions, the external cues available at learning were different from those available at recall, leading to retrieval failure.

Research on state dependent forgetting

Carter and Cassaday (1998) gave antihistamine drugs, which made participants slightly drowsy.

This creates an internal physiological state different from the usual state of being awake and alert.

Participants learned a long list of words either on or off the drug and then recalled the information either on or off the drug.

Findings:

In the conditions where there was a mismatch between internal state at learning and recall, performance was significantly worse.

So when cues are absent, there is more forgetting.

Rtreival failiure strength- research support

One strength is the impressive range of research that supports the retrieval failure explanation.

Studies on context- and state-dependent research show that a lack of relevant cues at recall can lead to context- and state-dependent forgetting in everyday life.

Eysenck and Keane (2010) argue that retrieval failure is perhaps the main reason for forgetting from LTM.

This evidence shows retrieval failure occurs in real-world situations as well as highly controlled conditions of the lab.

COUNTERPOINT

Baddeley (1997) argues context effects are actually not very strong, especially in everyday life.

Different contexts have to be very different for an effect to be seen.

Learning something in one room and recalling it in another is unlikely to result in much forgetting because environments are generally not different enough.

This means retrieval failiure is due to a lack of contextual cues may not explain much everyday forgetting.

Interference limitation- context and state dependence

One limitation is that it is difficult to seperate the effects of context-dependent and state-dependent forgetting.

Jaap Murre (2021) identified that in the deep-sea divers study, the external factors werent the only thing changing; internal factors also changed.

Changes in body temperature, oxygen levels and breathing patterns.

It may be that the changes in participants’ physiological state had a bigger influence on reduced rate of recall at the retrieval stage.

This suggests we cannot be sure what the results of Baddeley’s findings were due to.

Interference limitation- recall versus recognition

A limitation is that context effects may depend substantially on the type of memory being tested.

Godden and Baddeley (198) replicated their underwater experiments but used a recognition test instead of recall.

Participants had to say if they recognised a word from the list when read to them.

When recognition was tested, there was no context-dependent effect; performance was the same in all four conditions.

This suggests retrieval failure is a limited explanation for forgetting because it only applies when a person has to recall information rather than recognise it.

Research on leading questions

When asked a question, the wording may lead you to give a certain answer.

This is an issue in eyewitness testimonies, because police may direct a witness to give a particular answer.

Procedure:

Loftus and Palmer (1974) arranged for 45 participants to watch a film. clips of car accidents and then asked questions about the accident.

In the critical question, participants were asked, “about how fast were the cars going when they HIT each other”.

There were five groups of participants, and each group had a different word to replace hit: smashed, contacted, bumped, collided.

Findings:

Mean estimated speed was calculated for each participant group.

Contacted had a mean speed of 31.8 mph

Smashed had a mean speed of 40.5 mph

Leading question biased eyewitnesses’ recall of an event.

Why do leading questions affect EWT?

Wording of the question has no real effect on participants’ memories, but just influences how they decide to answer.

Loftus and Palmer conducted a separate experiment that supported the substitution explanation.

This proposes that the wording of a leading question changes participants’ memory of the film clip.

This was shown because participants who originally heard smashed were more likely to report seeing broken glass than those who heard hit.

The critical verb altered their memory of the incident.

Leading questions strength- real world application

One strength of research into leading questions is its practical uses in the criminal justice system.

Loftus (1975) presented evidence in court about the serious effects of leading questions on memory, which may lead to faulty convictions.

Police officers need to be very careful about phrasing questions when interviewing eyewitnesses.

This shows that psychologists can help improve the way the legal system works.

Leading questions limitation- evidence against substitution

Sutherland and Hayne (2001) showed participants a video clip, and when later asked leading questions, participants’ recall was more accurate for central details than for peripheral ones.

Presumably, participants’ attention was focused on central features, and these memories were relatively resistant to leading questions.

This suggests the original memories for central details were not distorted, an outcome not predicted by the substitution explanation.

Leading questions evaluation- demand characteristics

Lab experiments have shown that leading questions can be a cause of inaccurate EWT.

Zaragoza and McCloskey (1989) argue that many answers given by participants in lab experiments are due to demand characteristics.

Participants usually want to be helpful, so they guess when they’re asked a question and don’t know what to do.