Memory

Models of Memory

Multi-Store Model

Atkinson and Shiffrin (1968) proposed the multi-store model of memory, which suggests that memory is made up of three separate stores: the sensory register, short-term memory, and long-term memory.

Information first enters the sensory register through environmental input. If attention is paid to the information, it is transferred to short-term memory. Maintenance rehearsal allows information to be retained in short-term memory, while elaborative rehearsal transfers information into long-term memory.

Information may be lost from the stores through processes such as decay or displacement.

Coding refers to the format in which information is stored, capacity refers to the amount of information that can be stored, and duration refers to how long information can be held.

The sensory register has modality-specific coding, meaning it is based on the different senses. It has a very high capacity but a duration of less than half a second.

Short-term memory is coded acoustically, has a capacity of approximately 5 to 9 items, and has a duration of around 18 seconds.

Long-term memory is coded semantically, has a practically unlimited capacity, and can last for a lifetime.

Evaluation of the Multi-Store Model

Glanzer and Cunitz (1966) investigated the serial position effect by presenting participants with a list of words and asking them to recall them. Participants tended to remember words from the beginning and end of the list better than those in the middle. This supports the idea that short-term and long-term memory are separate stores.

Craik and Watkins (1973) argued that rehearsal alone does not explain transfer to long-term memory. They suggested that the type of rehearsal is more important than the frequency, which challenges the explanation provided by the multi-store model.

Case studies also provide supporting evidence. KF suffered a brain injury that impaired his short-term memory but left his long-term memory relatively unaffected. His performance differed depending on whether information was presented visually or acoustically, suggesting that short-term memory may consist of more than one store.

A limitation of the multi-store model is that much of the supporting research uses artificial tasks, such as memorising word lists. This reduces the validity of the findings, as these tasks do not reflect how memory is used in everyday life.

Research into Coding, Capacity and Duration

Baddeley (1966) investigated coding in memory by giving participants lists of acoustically similar, acoustically dissimilar, semantically similar, and semantically dissimilar words. He found that acoustically similar words were harder to recall in short-term memory tasks, while semantically similar words were harder to recall in long-term memory tasks.

Jacobs (1887) investigated capacity by presenting participants with increasing numbers of digits and asking them to recall them. He found that the average digit span was 9.3 items, while the average letter span was 7.3 items.

Miller (1956) suggested that the capacity of short-term memory is 5 to 9 items, which he referred to as “the magic number seven plus or minus two”. He also suggested that this capacity could be increased through chunking.

Peterson and Peterson (1959) investigated duration by giving participants consonant syllables to remember and preventing rehearsal by asking them to count backwards. They found that memory recall dropped significantly after 18 seconds, indicating the limited duration of short-term memory.

Working Memory Model

Baddeley and Hitch (1974) proposed the working memory model as an alternative to the multi-store model, suggesting that short-term memory is made up of multiple components.

The central executive is the main component and is responsible for directing attention and allocating resources to the other components. It has a limited processing capacity and no storage capacity.

The phonological loop is responsible for processing auditory information. It includes the phonological store, which holds spoken words, and the articulatory process, which allows for rehearsal. The capacity is around two seconds of verbal information.

The visuo-spatial sketchpad is responsible for processing visual and spatial information. The visual cache stores visual data, while the inner scribe records spatial information about the arrangement of objects.

The episodic buffer is a temporary store that integrates information from the phonological loop, visuo-spatial sketchpad, and long-term memory. It has a limited capacity of around four chunks.

Evaluation of the Working Memory Model

Case studies, such as that of KF, support the idea that there are separate stores for different types of information within short-term memory.

Dolcos et al. (2007) used brain imaging techniques and found that different areas of the brain are activated when performing tasks that involve different components of working memory. This supports the idea that working memory consists of separate subsystems.

A limitation of the working memory model is that there is little clarity about the role of the central executive. Some researchers suggest that it may consist of multiple components, which means that the model is not fully explained.

Another limitation is that research into memory often uses artificial tasks, reducing the ecological validity of the findings.

 

Explanations for Forgetting

Interference

Interference is an explanation for forgetting that occurs when one memory disrupts the recall of another.

Proactive interference occurs when older information interferes with the learning or recall of new information.

Retroactive interference occurs when new information interferes with the recall of previously learned information.

Interference is more likely to occur when the information being learned is similar.

McGeoch and McDonald (1931) found that participants who learned lists of words with similar meanings showed the poorest recall, demonstrating the effects of interference.

Evaluation of Interference

Baddeley and Hitch (1977) studied rugby players and found that those who had played more games were less able to recall the names of teams they had played against. This supports the role of interference in forgetting.

Tulving and Psotka (1971) found that when participants were given cues, their recall improved. This suggests that interference may not cause permanent forgetting, but rather temporary retrieval failure.

Underwood (1957) found evidence for proactive interference, as participants who had previously taken part in similar experiments showed poorer recall of new information.

A limitation is that much of the research into interference is based on artificial tasks conducted in laboratory settings, which reduces ecological validity.

Retrieval Failure

Retrieval failure occurs when information is present in memory but cannot be accessed due to a lack of appropriate cues.

The encoding specificity principle states that cues must be present both at the time of learning and at the time of recall in order to be effective.

Context-dependent forgetting occurs when external cues present during learning are not present during recall. Abernathy (1940) found that students performed better when tested in the same environment in which they had learned the material.

State-dependent forgetting occurs when an individual’s internal state differs between learning and recall. Hardman (1998) found that participants who learned information while exercising were more likely to recall it when exercising again.

Evaluation of Retrieval Failure

Godden and Baddeley (1975) found that divers recalled words more accurately when learning and recall took place in the same context, either underwater or on land.

Goodwin et al. (1969) found that participants who were intoxicated during learning showed better recall when intoxicated again.

These findings demonstrate that matching context or state can improve recall, which has practical applications for revision strategies.

 

Factors Affecting the Accuracy of Eyewitness Testimony

Leading Questions

Loftus and Palmer (1974) investigated the effect of leading questions on eyewitness testimony by showing participants films of car accidents. They then asked participants to estimate the speed of the cars using different verbs such as “smashed” or “contacted”.

They found that the verb used influenced speed estimates, showing that leading questions can distort memory.

Evaluation of the Effect of Leading Questions

The study had a high level of control, allowing researchers to establish a cause-and-effect relationship.

It also had some level of realism, as the scenario was similar to real-life situations involving eyewitnesses.

In a follow-up study, participants who heard the word “smashed” were more likely to report seeing broken glass, even though none was present. This shows that leading questions can alter memory.

This research has practical applications, as it has influenced police interviewing techniques.

Post-Event Discussion

Gabbert et al. (2003) investigated the effect of post-event discussion by showing participants different versions of the same event and then asking them to discuss what they saw.

They found that many participants recalled information they had not actually seen, demonstrating the effects of memory conformity and memory contamination.

Memory conformity occurs when individuals agree with others to gain approval or because they believe they are correct.

Memory contamination occurs when memories are altered or combined during discussion.

Evaluation of the Effect of Post Event Discussion

A limitation of this research is that it lacks ecological validity, as participants are aware they are taking part in a study.

It is also difficult to determine whether inaccuracies are due to memory distortion or social influence.

However, research has shown that post-event discussion affects individuals of different ages, suggesting that the findings are generalisable.

Anxiety

Anxiety can influence the accuracy of eyewitness testimony. In high-anxiety situations, individuals may focus on central details, such as a weapon, rather than peripheral details. This is known as the weapon focus effect.

Johnson and Scott (1976) found that participants were less accurate in identifying a suspect when a weapon was present compared to when a neutral object was present.

Evaluation of the Effect of Anxiety

Research using eye-tracking technology shows that individuals focus their attention on the weapon rather than the face of the suspect.

Christianson and Hubinette (1993) found that real-life witnesses to crimes were often highly accurate, even after long periods.

Pickel (1998) suggested that unusualness rather than anxiety may explain reduced accuracy.

Cognitive Interview

The cognitive interview is a method used to improve the accuracy of eyewitness testimony by using specific recall techniques.

One technique is report everything, which encourages witnesses to include all details, even if they seem unimportant.

Another technique is mental reinstatement of context, where the witness is asked to recall the environment and their emotional state at the time of the event.

Witnesses may also be asked to recall events in a different order to prevent reliance on expectations.

Changing perspective involves recalling the event from a different viewpoint.

The enhanced cognitive interview includes additional techniques such as establishing rapport, maintaining eye contact, and asking open-ended questions.

Evaluation of Cognitive Interview

Köhnken et al. conducted a meta-analysis and found that the cognitive interview increases the amount of accurate information recalled, although it may also increase the amount of inaccurate information.

Milne and Bull (2002) found that combining different techniques can improve recall.

Geiselman (1999) found that the cognitive interview may be less effective for children under the age of eight, as they may struggle to understand the instructions.