Paper 1 - Cognitive Approach - Models of Memory

Memory

A cognitive process used to encode, store and retrieve info

-> 2 types: declarative and procedural (non-declarative)

Declarative memory + 2 examples of declarative memories

Memories which can be consciously recalled (e.g. facts and people).

- Episodic - the memory of autobiographical events that occurred at a particular time and place.

- Semantic - general knowledge of facts and people, including schemas and people.

Procedural memory

Unconscious memory of skills and how to do things.

Multistore Model of Memory (MSM) - Atkison and Shiffrin (1968)

The MSM explains how information flows through 3 stores, each having different capacities and durations.

Key features of the MSM

- It is a structural model consisting of 3 components (sensory memory, STM and LTM).

- STM and LTM are unitary (separate and distinct) stores.

- Info passes from store to store in a linear way.

- Rehearsal and repetition is needed to pass info from STM to LTM - research has suggested that the more info has been rehearsed, the better it's remembered.

- Each store has it's own characteristics in term of coding (the process in which it stores info), capacity (how much info it can hold), and duration (how long it can hold info).

- Sensory memory doesn't process info but holds it until it's either passed to the STM or lost. Attention is required for this info to pass to the STM store.

- STM holds info for 6-12s unless it is rehearsed, in which case it moves onto LTM.

Coding of sensory memory

Information is stored in an unprocessed way and comes from sense organs (e.g. eyes and nose). There are different sensory stores for different sensory inputs:

- Echoic store: auditory info

- Iconic store: visual info

- Haptic store: tactile info

- Gustatory store: info on taste

- Olfactory store: info on smell

Capacity of sensory memory

Very large (e.g., over 100 million cells in one eye, storing info)

Duration of sensory memory

Limited - Around less than half a second. Different types of information within each of the stores decays at different rates.

-> There are individual differences - for example, some children have eidetic (photographic) memory and can hold visual info for a few mins.

Coding of Short Term Memory (STM)

Information comes from the sensory store in it's original, raw form (e.g. sound or vision). Info is encoded in several ways:

- Visually: by thinking of the object's image.

- Acoustically (sound): repeatedly saying the object's name (main way of encoding).

- Semantically (meaning): using the info known about the object.

Capacity of STM

Limited - only a small amount of information is held. Between 5-9 items. It can be increased through chunking (e.g., SOSAB CITVFBI)

Duration of STM

The amount of time info stays without being lost is limited to about 30s. This can last longer by rehearsal (repetition) of the info. Through rehearsal, info can be transferred to the LTM, where it will last longer.

Coding of Long Term Memory (LTM)

Information is shaped into a representation of memories. The deeper the level of processing, the stronger the coding of info. This means the memory is more retrievable. Research suggests it tends to be processed semantically.

Capacity of the LTM

Unlimited - info may be lost due to decay and interference, but loss of info doesn't occur because of limitations in capacity.

Duration of LTM

A lifetime. Info can last longer if it's well-coded. Info in STM needs to be rehearsed, otherwise it's forgotten, whereas info in this store doesn't have to be continuously rehearsed.

MSM - Glanzer and Cunitz's study (1966): Aim

To demonstrate that the U-shape of the serial position curve ('bimodial serial position curve') is caused by 2 separate stores for short term and long term memory.

Glanzer and Cunitz: Method of Experiment 1 (LTM)

The participants were 240 males enlisted in the army, and were asked to remember the same list of words that were read to them in different ways. They were randomly allocated to 5 conditions:

1S/P - each word presented once at a 3s rate (single spacing)

2S - each word presented once at a 6s rate (double spacing)

3S - each word presented once at a 9s rate (triple spacing)

2P - each word presented twice in succession at a 3s rate

3P - each word presented 3 times in succession at a 3s rate.

Glanzer and Cunitz: Results of Experiment 1

The repetition of the word had no significant effect on the serial position curve, and neither repetition nor spacing had any effect at the end of the curve. However, as spacing increased from 3s to 6s to 9s intervals, the recall at the beginning and the middle of the curve correspondingly improved.

This is known as the primacy effect and corresponds to the effect on the LTM graph. There was a significant difference in the number of early items recalled between those who had the 3s, 6s and 9s intervals.

Glanzer and Cunitz: Method of Experiment 2 (STM)

46 men (opportunity sample from army enlists) were individually shown 15 15-word lists under 3 conditions: immediate recall; recall after 10s, with interference of counting backwards from a given, random number; recall after 30s, with the same interference task.

Each participant received a different set of lists (words were assigned randomly to lists) and a different sequence of delay conditions (order of delay conditions within 15 lists was assigned randomly).

Glanzer and Cunitz: Results of Experiment 2

The 10s delay was sufficient to remove most of the end peak. This means the delay and interference removed the recency effect associated with the STM. With a 30s delay there was no trace of the recency effect.

Glanzer and Cunitz: Conclusion (both experiment)

These results support the hypothesis of 2 distinct storage mechanisms for LTM (shown by the increase in primacy effect when delay was increased) and STM (shown by the decrease in recency effect when delay and interference prevented rehearsal). Therefore, this supports the idea that the STM and LTM are unitary stores as outlined by the MSM.

Glanzer and Cunitz: Evaluation (strengths)

+ It was a lab experiment. It was a very carefully designed experiment that manipulated the IV of time-spacing (experiment 1) and the IVs of time delay and interference before recall (experiment 2) while controlling all other variables. The experiment also used a standardized procedure, making it replicable and therefore reliable.

Glanzer and Cunitz: Evaluation (limitations)

- The participants were all adult males. This means the results of the experiment can not be generalized to everyone/the general public, as the sample is not representative. Furthermore, the participants career may have impacted their ability to memorize. This means the experiment would need to be repeated with women and children to see if there would be any differences in results.

Milner (1966) HM: Background information

- HM was hit by a cyclist at age 7 and sustained a serious head injury. Epileptic attacks began at age 10 (assumed to be accident-related). At age 27, he became so incapacitated by his seizures that he couldn't lead a normal life and medication didn't help him.

- William Scoville performed experimental surgery on HM where he removed tissue from the medial temporal lobe (including the hippocampus) on both sides of HM's brain.

- Afterwards, HM's retrograde amnesia diminished (memory for events prior to the operation).

- HM mainly suffered from anterograde amnesia (couldn't form new memories).

Milner (1966) HM: Aim

To better understand the effects surgery had on HM

Milner (1966) HM: Method

Milner used many different strategies (an example of method triangulation in case studies) including psychometric testing - IQ testing was given to HM. His results were above average. They also carried out direct observation of his behavior and conducted interviews with HM and his family. They also used cognitive testing: for example, memory recall tests and learning tasks (e.g. reverse mirror drawing).

Corkin later did an MRI at 1992 and 2003 to determine the extent of the damage done to HM's brain.

Milner (1966) HM: Results

- HM had a capacity for working memory since he was able to carry on a normal conversation. This requires a minimal level of retention of the things heard and said. HM could recall the number 548, even after 15 minutes (through constant rehearsal). However, HM couldn't recall the number after the task.

- Procedural memories (motor skills) were well-maintained; he knew how to mow a law. His performance on new skills like reverse-mirror drawing (in which he had to acquire new hand-eye co-ordination) improved, although he never remembered learning the skill (when Milner asked him to do it, he would say he'd never done it before).

- Corkin's MRI showed that parts of HM's temporal lobe (including the hippocampus) had the most damage, although it was less extensive than Scoville estimated. Damage to the hippocampus explains the problem of transferring information from the STM to LTM, as in this area, the neurotransmitter acetylcholine is believed to play an important role in learning and the formation of memories.

Milner (1966) HM: Conclusion(s)

- The memory systems in the brain constitute a highly specialized and complex system.

- The hippocampus plays a critical role in converting memories of experiences from STM to LTM.

- However, researchers found that STM is not stored in the hippocampus as HM was able to retain info for a while after rehearsing it.

- HM retained some memories for events long before his surgery, indicating that the medial temporal region is not the site of permanent storage but instead plays a role in the organization and permanent storage of memories elsewhere in the brain.

- Implicit memory contains several stores (e.g. procedural memory, emotional memory, skills and habits). Each of these areas is related to different brain areas.

Milner (1966) HM: Evaluation (strengths)

+ Milner's research was a case study. The study was longitudinal (over 50 years). This means change could be observed over time, giving a detailed, in-depth view of HM's cognitive processing. HM could not acquire new episodic and semantic knowledge. This suggests the brain structures removed from his brain are important for info transfer from STM to LTM. This supports the MSM as it suggests there are separate and distinct stores for STM and LTM, as the model suggests.

Milner (1966) HM: Evaluation (limitations)

- Some of the study was retrospective in nature. HM was not studied before the accident. This means we don't have a lot of data on HM's cognitive abilities before the accident, and making comparisons to his memory beforehand is difficult. Therefore, this raises issues about how valid the research is, and whether it fully evidences support for the MSM.

- Case studies cannot be easily replicated. However, there are several other case studies of patients like HM, for example, Clive Wearing - which confirm the findings. Cannot be generalized.

Evaluation of the MSM (strengths)

+ It is considered to be an important and influential model. The MSM was the first theoretical model to explain the process and structure of memory. It has enabled further understanding, further research and a refined model of memory (working memory). Therefore, this shows the importance of the MSM, allowing us to gain understanding of a complex process like memory.

Evaluation of the MSM (limitations)

- It is too simplistic. The model considers memory to function in terms of a unitary short term and long term memory store. Research has shown that there are multiple types of STM (as evidenced by the WMM), and LTM consists of episodic, semantic and procedural memory. Therefore, it's an oversimplified representation of memory. Memory is more complex than a simple STM and LTM, and the MSM doesn't account for this.

- The theory is reductionist - it focuses on structure rather than process. The model solely focuses on rehearsal as the mode of processing between memory stores. However, we do not rehearse all info that enters LTM. Similarly, we can rehearse and yet fail to process info from STM to LTM. This is a limitation of the model, as it only provides a limited explanation of how memories actually work.

Working Memory Model (WMM) - Baddeley and Hitch (1974)

- Hypothetical model of STM that includes several components - contrast to MSM's version of STM as one big store.

- Explanation of how STM is organized and functions. Baddeley and Hitch argue that the STM was an active store which holds several pieces of info simultaneously (so potentially has a number of stores).

- It was suggested from studies that used dual-task technique where the participants essentially multi-tasked. They found participants that did 2 tasks related to listening performed less well than those doing 2 tasks involving listening and vision.

Central Executive (CE) - oversees and co-ordinates the components of working memory.

- Attention control system that monitors and co-ordinates the operations of other subordinate components (slave systems).

- Decides how and when the slave systems are used.

- Has the capacity to focus attention, to divide attention between 2 or more sources, and to switch attention from one task to another.

- Has a limited capacity.

- Is modality free - it can process any sensory info, whether is be visual or auditory.

CE Part 2 - Attention control (happens in 2 ways)

1. Automatic level - based on habits that rely on schemas in LTM and controlled more or less automatically by stimuli from the environment. Includes routine actions (e.g. cycling to school).

2. Supervisory attention - deals with planning and decision making. Creates new strategies when old ones are no longer sufficient. Also active in emergency situations, situations requiring self-regulation, and is also capable of considering alternate plans of action and choosing the most favorable.

Phonological loop (PL) - deals with auditory information

- Auditory component of STM and is divided into 2 components.

1. Articulatory control system (inner voice) - can hold info in verbal form (e.g. trying to remember a phone number and repeating it to yourself). Also believed to hold words ready for cognitive tasks (e.g. preparing to speak). Rehearses info from PL. Frequent rehearsal = more likely to be stored in LTM.

2. Phonological store (inner ear) - holds auditory memory traces. Research shows memory traces only last 1.5-2s if not rehearsed by the articulatory system. The phonological store can receive directly from sensory memory in the form of auditory material, from LTM in the form of verbal info, and from the articulatory control system.

Visuospatial Sketchpad (VSS) - deals w/ visual info

- Visual component of STM

- Temporary store for visual and spatial info from either sensory memory or LTM.

- Visual processing includes storage and manipulation of visual patterns and spatial movements in 2 or 3 dimensions.

Episodic buffer

- Temporarily holds several sources of info active at the same time, while a person considers what is needed in the present situation - this includes auditory and visual info, as well as info from the LTM.

- Acts as a temporary and passive display store until the info is needed - but has a limited capacity.

- Baddeley argues that the episodic buffer is responsible for conscious awareness.

- Articulatory suppression: the process of inhibiting memory performance by speaking while being presented w/ an item to be remembered.

WMM - Shallice and Warrington's study (1970): Aim

To investigate the relationship between LTM and STM, when the STM is impaired, looking especially at memory trace formation and memory retrieval.

Shallice and Warrington (1970): Method

Case study conducted on KF (28 y/o male who sustained a left parieto-occipital fracture in a motorcycle accident when he was 17. He was left unconscious for 10 weeks). Whether he was LH or RH is unknown, but the left parietal lobe is often more active in RH people (and is known for handling symbols like letters). Fine motor movements in his RH were impaired and 2 years later he started having seizures. His psychological assessment found that he couldn't repeat letters or numbers, a defect of STM, although his LTM remained intact.

Shallice and Warrington carried out an experiment about repetition of numbers, letters and words. Strings (lists spoken out loud) of 1,2,3,4 items were presented for each of the 3 types of verbal material (number, letters and words). The numbers and letters were chosen randomly and not repeated w/i a string. Words were chosen randomly from 4 and 5 letter words of high frequency.

Shallice and Warrington (1970): Results

- Auditory performance was clearly related to the number of items in each string. KF could only repeat 1 item reliably, and the proportion of items decreased as string length increased.

- Performance for 2,3 and 4 item strings was poor. Repetition for numbers was better than for letters.

- Auditory problems were ruled out, yet a later experiment showed that his memory for visual material was better than for auditory material.

Shallice and Warrington (1970): Conclusion

- KF's STM was severely impaired as its capacity was greatly reduced; later experiments showed his LTM was intact.

- The difference between auditory and visual memory capacity suggests 2 separate stores for these modalities, supporting the WMM. Furthermore, KF had an intact LTM and impaired STM contradicts the MSM theory that material in the LTM has first been processed in the STM.

Shallice and Warrington (1970): Evaluation (strengths)

+ It was a carefully designed experiment on just one person as part of a case study. The variables of how the material was presented, KF's comprehension and expressive language functions were all isolated and controlled.

Shallice and Warrington (1970): Evaluation (limitations)

- There is no analysis of why the memory for numbers is better than that for either letters or words. No alternative explanation is given of how auditory info is transferred into LTM if STM is so impaired.

- Since the research method used was a case study, it is difficult to generalize the findings. This is because only one patient - KF - was used and he may have been exhibiting emic behavior. This means the results from one case cannot be generalized to all people.

Evaluation of WMM (strengths)

+ Experiments using dual-task techniques seem to provide support to the model. In dual-task experiments, a participant may be asked to tell a story to another person while at the same time performing a second cognitive task (e.g. learning a list of numbers). Such concurrent tasks impair overall performance. The WMM suggests that if two tasks interfere, so that one or both are impaired, they are using the same component in STM.

+ Brain scans have shown that different parts of the brain are activated by different tasks. This supports the WMM because the model suggests different types of info are held in diff ways.

Evaluation of WMM (limitations)

- There's little direct evidence for how the CE works and what is does and its processing capacity has never been measured. The role of the CE is unclear, although Baddeley and Hitch proposed it was the most important part of the WMM. For example, they suggested that the CE has its own limited capacity, but it's impossible to measure this separately from the capacity of the PL and VSS. Furthermore, how the various components of the model interact is unclear.

Differences between the MSM and WMM

- The MSM is a complete theory of memory, from STM to LTM, while the WMM is a theory of just the STM.

- The MSM views the STM as a unitary store where in material is retained through repetition and the focus is on capacity, encoding and duration, and material is processed mainly acoustically.

- The WMM shows the STM as a processing area divided into 3 interacting components: the CE, PL and VSS. The episodic buffer that was added later by Baddeley acts to mediate between the STM and LTM.

- The MSM focuses on capacity, encoding and duration, while the WMM can also be used to explain processes (e.g. thinking and problem solving).