Types of Long Term Memory
Episodic: The memory of autobiographical events (times, places, associated emotions, and other contextual who, what, when, where, why knowledge) that can be explicitly stated. It is the collection of past personal experiences that occurred at a particular time and place. For example, if you remember the party on your 6th birthday, this is an episodic memory. They allow you to figuratively travel back in time to remember the event that took place at that particular time and place. They are ‘time stamped’ (you know when the memory was made) and ‘declarative’ (you have to consciously ‘search’ for the memory).
Semantic: Sometimes called generic memory, this refers to the memory of meanings, understandings, and other concept-based knowledge. Semantic memory underlies the conscious recollection of factual information and general knowledge about the world. For example, knowing what the capital city of Italy is, or how many pounds there are in a stone. The memories are not usually time-stamped, and they are declarative.
Procedural: The memory for the performance of particular types of action/skill. Procedural memory guides the processes we perform and most frequently resides below the level of conscious awareness. When needed, procedural memories are automatically retrieved and utilised for the execution of the integrated procedures involved in both cognitive and motor skills, from tying shoes to flying an airplane to reading. These memories are not usually time-stamped, and are non-declarative (implicit)- they don’t need to be consciously recalled.
- The case of Clive Wearing supports that there are different types of LTM. Following a brain infection, Wearing’s procedural memory seemed intact (e.g. being able to dress himself and even play the piano), but his episodic memory was severely damaged. When his wife left the room and returned, even after only a few minutes, he would greet her as if they had not seen each other for years. He kept a diary in which he constantly wrote that he was just regaining consciousness every few minutes. This supports that there are different stores for different types of LTM.
- Brain scanning studies show that different areas of the brain are active when performing tasks involving different types of LTM. This supports that types of LTM are physically different.
- Cases such as Clive Wearing are hard to use as evidence as they are case studies (studies of one individual). There is no way to test the memory of such individuals before their brain damage, and it is hard to use one person’s case to apply to the entire population. This weakens the supporting evidence for types of LTM.
- Discuss different types of long-term memory. (16 marks - 6 outline - around 3 paragraphs; 10 evaluate - around 3-4 evaluation points)
- Your answer should include: Episodic / Sematic / Procedural / Brain / Scanning
The Working Memory Model
The WMM is an account of how short-term memory functions when working on a task. It is made up of:
Central executive: Allocates ‘slave’ systems to tasks, and has a very limited processing capacity
Phonological loop: Deals with auditory information, coded acoustically. Is subdivided into the phonological store (stores words you hear) and articulatory process/control system (allows for maintenance rehearsal, has around a two-second capacity). Having to recite a list of words just read to you would use this store.
Visuospatial sketchpad: Stores visual and spatial information, and has a capacity of around 3-4 objects. Is subdivided into the visual cache (stores visual data) and inner scribe (records arrangement of objects). Counting the number of windows in your house would use this store.
Episodic buffer: added in 2000, this integrates visual, spatial, verbal information and maintains a sense of time sequencing. It has a capacity of around 4 chunks. And links working memory to LTM and perception.
- The study of KF supports the WMM- his phonological loop appeared damaged, but his visuo-spatial sketchpad worked ok.
- Baddeley et al (1975) found that when participants had to perform two tasks simultaneously which used the same system, they found it very difficult. When performing two tasks using different system, performance was unaffected. This shows that there are different systems for different types of information, and that they have limited capacities.
- The central executive has been criticised for not being explained enough. Other than its role in paying attention and allocating resources, it is not known exactly how it functions, meaning that the WMM is lacking in clarity.
Interference theory suggests that information in LTM conflicts with each other, resulting in a distortion or blocking of a memory. There are two types of interference. Proactive is when an older memory moves forward to interfere with a newer one, for example calling a new partner by your old partner’s name. Retroactive is when a newer memory moves backward to interfere with an older one, for example learning a list of words, then a second list, then struggling to recall the first list.
The effect of the similarity of information was shown by McGeoch and McDonald (1931) who found that when participants were given a list of words to learn followed by a second list, recall of the first list was worse when the second set of information was more similar (for example, a list of words with the same meanings as the originals). This shows that interference becomes more likely the more similar the information is.
- Interference has been supported by several laboratory studies, such as McGeoch and McDonald, suggesting the explanation is true.
- Much of the supporting evidence is obtained using artificial tasks, such as learning meaningless word lists and having to recall them 20 minutes later, which is not reflective of how memory works. This therefore weakens the explanation.
- Baddeley and Hitch (1977) found that when rugby players recalled the names of teams they had played in a season, if they had played more games the task was more difficult (rather than if there had been a long time since they had played the matches). This shows how interference is a better explanation of forgetting than the mere passage of time.
Encoding specificity principle: Tulving suggested that when memories are created, associated cues are stored at the same time. If these cues are not present when trying to recall the information, forgetting will take place. For example, when going downstairs, you may forget what you went down for. By returning to the scene of the memory (going back to your bedroom), the ‘cue’ of the environment you were in acts as a trigger for the recall of the memory- the reason why you went downstairs.
Context-dependent forgetting: The external environment differs between learning and recall This is shown by Godden and Baddeley’s deep-sea diver study, in which divers had to learn a list of words underwater (or on land), and then recall them underwater (or on land). Conditions in which the environment of learning matched that of recall resulted in a 40% higher recall rate.
State-dependent forgetting: The internal state of the person (e.g. alertness) differs between learning and recall. This is shown by Carter and Cassaday’s anti-histamine study, in which participants had to learn passages of words whilst on anti-histamines (or not on them), and then recall them on anti-histamines (or not on them). The anti-histamines induced a feeling of drowsiness in the participants. Conditions in which the state of learning matched that of recall resulted in a significantly higher recall rate.
- Research studies such as Carter and Cassaday, Godden and Baddeley, and many others, demonstrate and support the explanation of cue-dependent forgetting.
- It has been suggested that the context and state effects are not that strong, and that they would need to be very different for forgetting to take place. The deep-sea diver study is an example of this. In everyday life, the differences between learning and recall do not differ this much, weakening this as an explanation for forgetting.
- In a replication of the deep-sea diver study there was no context effect when divers had to recognise words from the list (rather than having to simply recall them). This shows that context effects may only be applicable to certain types of memory test, weakening the explanation.
Eyewitness testimony (EWT) is the ability of people to remember details of events they have seen, such as crimes or accidents.
Leading questions: The wording of a question can alter a person’s recall of an event. Loftus and Palmer (1974) showed participants a film clip of a car accident, then asked them questions. One question was changed for different groups of participants- ‘about how fast were the cars going when they hit each other?’. For other groups, ’hit’ was replaced with ‘smashed’, ‘bumped’, ‘contacted’, or ‘collided’. Those given ‘smashed’ as their verb estimated a speed of 40.5mph. Those given ‘contacted’ estimated 31.8mph. This shows how the phrasing of the question suggested how fast the car was going, and affected the participant’s answer (the response-bias explanation). Another explanation is the substitution explanation, where the question actually changes the witness’s memory. In another study by Loftus, an additional question was asked- ‘did you see any broken glass?’ (there was none). Those given the ‘smashed’ question were more likely to say that they did see broken glass.
Post-event discussion: Following an event, witnesses may discuss what they have seen, resulting in an altering or distortion of their own memory. Gabbert et al (2003) studied participants in pairs. Participants watched a video of the same crime filmed from different points of view. This meant that each participant could see things that the other could not (for example, the title of a book being carried). Both participants discussed what they had seen before individually completing a test of recall, testing whether they (not them and their partner) had seen certain things. It was found that 71% of the participants mistakenly recalled aspects of the event that they did not see in the video but had picked up in the discussion. A control group, where there was no discussion, was also tested, and the number of errors made like in the experimental condition was 0%. The conclusion was that witnesses often go along with each other, either to win social approval or because they believe the other witnesses are right and they are wrong.
- Studies such as Loftus and Palmer take place in labs, watching film clips, meaning that the emotional aspect of witnessing an accident or crime is not present. The experiments may therefore not tell us about how EWT may work in the real world.
- Answers that participants may give may be due to them wanting to please the experimenter or guess what the experimenter wants from them (demand characteristics), so they may not answer in this way if recalling a real-life event. This reduces the validity of these findings.
- The findings from these studies have potentially useful real-world applications- they can be used to amend how questions are asked in police interviews, for example. This strengthens the value of research into EWT.
- Outline the effect of misleading information on eyewitness testimony. Refer to the scenario in your answer. (4 marks - around 1-2 paragraphs)
- Your answer should include: Response / Bias / Substitution / Leading
- Bob is being questioned about an assault he witnessed in town the previous weekend. The police officer asks him, ‘did you see the knife the attacker was carrying?’ Bob responds, ‘I’m not sure I remember seeing a knife. I think so… yes, thinking about it, I did see the knife.’ Outline the effect of misleading information on eyewitness testimony. Refer to the scenario in your answer. (4 marks - around 1-2 paragraphs)
- Your answer should include: Response / Bias / Substitution / Leading
Anxiety has a positive effect on recall: Yuille and Cutshall (1986) studied a real-life robbery of a gun shop. 13 witnesses took part. They found that participants who reported experiencing the highest levels of stress were more accurate in their recall of details of the event than those that reported feeling less stressed (88% compared to 75%). This suggests anxiety can have a positive effect on EWT.
Anxiety has a negative effect on recall: Johnson and Scott (1976) conducted a study using two groups of participants. One group heard an argument in an adjacent room, followed by glass breaking, then a man walked into the room holding a pen with grease on his hands. A second group saw the man walk in with a paper knife, with blood on his hands, to creat a higher level of anxiety than the other condition. 49% of the ‘pen group’ later accurately identified the man in a line-up, compared to 33% of the ‘knife group’. This suggests anxiety has a negative effect on EWT, as witnesses will focus on the weapon as a source of anxiety and not concentrate on any other details (the tunnel effect).
Yerkes-Dodson law/curve: given the contradictory findings, it has been concluded that a moderate amount of anxiety can have a positive effect on recall, but once the level of anxiety gets too great, performance will decline:
- The Johnson and Scott study may have actually tested surprise rather than anxiety over the weapon. Pickel (1988) found that participants were less accurate with recall when viewing a scene in a hairdressers including items such as a raw chicken (when compared to scissors, for example). The internal validity of Johnson and Scott is therefore in question.
- Field studies such as Yuille and Cutshall cannot be controlled, for example how good the participant’s memories are generally, or whether they talked about what they saw. The research is therefore weakened as a result.
- Creating anxiety for the purpose of testing this as a variable creates ethical issues, meaning the effect of anxiety on EWT is hard to study in a controlled environment. In addition, anxiety may be only one of a range of emotional (and other) influences on EWT, so the Yerkes-Dodson law is too simplistic.
The Cognitive Interview
Fisher and Geiselman developed the cognitive interview (CI) as a way of improving the accuracy of EWT. It has four elements:
- Report everything: the witness recalls every possible detail of the event, because minor details may act as a cue to trigger more important information.
- Reinstate the context: the witness is encouraged to return to the scene of the event (which could be real or imaginary), in the hope that this may provide cues to help recall detail. For example, imagining what the weather was like, what else happened that day, and so on.
- Reverse the order of recall: for example, starting with the last thing they remember. This is to prevent the witness’s expectations of what happened interfering with their memory of what actually happened.
- Change the perspective: for example, reporting what another witness or a victim may have seen. This is done to prevent reporting of the individual’s expectations, as in reverse the order.
The enhanced cognitive interview was developed in 1987 and added further elements to the CI, focusing on the dynamic between the interviewer and witness- for example, when to maintain eye contact and how long for, asking open questions, and speaking slowly.
- The CI is very time-consuming, and many police forces don’t have the resources to properly use it, limiting its usefulness as an interview technique.
- Milne and Bull (2002) found that the CI does lead to more information being reported, especially ‘report everything’ and ‘reinstate the context’. This strengthens the CI, as it suggests it is useful.
- Many variations of the CI are used by police forces, making it hard to accurately assess the effectiveness of the technique.
- What is the capacity of STM?
- Your answer should include: 7 / Chunks
- Who conducted research into the duration of STM?
- In the multi-store model, what causes information to be transferred from sensory memory into STM?
- What type of LTM is your knowledge of facts about the world?
- ‘Your memory of how to play tennis.’ What type of LTM is this?
- What part of the working memory model deals with spoken material?
- Your answer should include: Phonological / Loop
- When an older memory interferes with a newer one, this is known as what?
- Your answer should include: Proactive / Interference
- In Loftus and Palmer’s study, which word produced the highest speed estimate?
- Who suggested that a moderate level of anxiety is beneficial for EWT?
- Your answer should include: Yerkes / Dodson
- ‘Imagine yourself standing at the scene of the crime as you were witnessing it.’ What cognitive interview technique is this?
- Your answer should include: Reinstate / Context