AS: Cognitive psychology - Memory

AS: Cognitive psychology - Memory

1. Memory models

   • Multi – store model (MSM) – an explanation of memory that sees information flowing through a series of storage systems. Created by Atkinson & Shiffrin (1968) and is made up of 3 permanent structures: sensory register (SR), STM and LTM. Each stage differs in coding (the form in which information is stored), capacity (how much information can be stored) and duration (how long the information can be stores for). Information gathered by the sense organs enters the SR. Only the information paid attention to is passed into STM for further processing. This information is actively processed enough (through rehearsal) to transfer to LTM for more permanent storage.
     • SR – not under cognitive control, automatic response to the reception of sensory information by the sense organs. • Coding: information is stored in a raw, unprocessed form with separate sensory stores for different sensory inputs (echoic=auditory, iconic=visual, haptic=touch, gustatory=taste, olfactory=smell). • Capacity: each sensory memory store is very large, with the information contained being in an unprocessed, highly detailed and ever-changing format. • Duration: all sensory memory stores have limited duration, each one is not constant as each store decays at different rates. Evidence shows that duration decreases with age.
     • STM – temporarily stores information from the SR, contains information currently being thought about. •Coding: information from the SR is encoded into a form STM can deal with e.g. visually, acoustically or semantically. Research (Baddeley) suggests that acoustic is the main form of coding •Capacity: limited, research suggests the magic number 7±9. But this can be increased by chunking. •Duration: 30s is the maximum amount of time information can stay within STM without being lost. This can be extended by rehearsal of information that can transfer information into LTM.
     • LTM – information stored from 30s to a whole lifetime, several different types but not of equal strengths, LTMs may change or merge with other LTM over time, shaping and storing LTMs are spread through multiple brain regions. • Coding: information is shaped into representation of memories. It will be stronger (and more retrievable) the deeper the level of processing of a stimulus that occurs while being experienced. With verbal material, coding in LTM is mainly semantic although it does occur in other forms too, indicating a visual and acoustic code. • Capacity: potential capacity is unlimited but some information may be lost by decay or interference. • Duration: depends on an individual’s lifespan as memories can last for a lifetime. Duration increases if originally well coded and certain LTMs have longer duration i.e. based on skills rather than facts. Information in LTM doesn’t have to be continuously rehearsed to be retained.
   • Working memory model (WMM) – an explanation that sees short-term memory as an active store holding several pieces of information simultaneously. Created by Baddeley and Hitch (1974), they argues that STM was more complex and it was an ‘active store’ holding several pieces of information as they were being worked on. They proposed a multi-component working memory (WM) to replace the single STM store in the MSM of initially 3 components: central executive (CE) (head of the model) and 2 slaves, the visuo-spatial sketchpad (VSS) and the phonological loop (PL). a fourth component, the episodic buffer (EB) was added in 2000.
     • Central executive (CE) – component of the WMM that oversees and co-ordinates the components of the working memory. It acts as a filter to determine which information is and isn’t attended to from the sense organs. It directs information to the slave systems and collects responses. It’s limited in capacity and can only effectively cope with one strand of information at a time. D’Esposito et al. (1995) found using fMRI (functional magnetic resonance imaging) scans that the prefrontal cortex was activated when verbal and spatial tasks were performed simultaneously, but not when performed separately, suggesting the brain area to be associated with the working of the CE.
     • Phonological loop (PL) – component of the WMM that deals with auditory information. It deals with auditory information and the order of the information, so confusions occur with similar sounding words. It’s similar to the rehearsal system of the MSM, with a limited capacity determined by the amount of information that can be spoken out loud in about 2 seconds. Baddeley (1986) divided the Pl into 2 sub-parts, the primary acoustic store (PAS) (inner ear, stores words heard) and the articulatory process (AP) (inner voice, allows sub-vocal repetition of information within the store and is linked to speech production). Trojani & Grossi (1995) reported a case study of SC, who had brain damage affecting the functioning of his PL but not his VSS, suggesting that the PL is a separate system.
     • Visuo-spatial sketchpad (VSS) – component of the WMM that deals with visual information and the physical relationship of items. Inner eye, is a temporary store for visual and spatial items and the relationship between them. It helps individuals to navigate around and interact with their physical environment, with information being coded and rehearsed through the use of mental pictures. Logie (1995) suggested sub-dividing the store into a visual cache (VC) which stores visual material about form and colour, and an inner scribe (IS) which handles spatial relationships and rehearses and transfers information in the VC to the CE.
     • Episodic buffer – component of the WMM that serves as a temporary store of integrated information from the CE, PL, VSS and LTM. It was introduced to explain how it is possible to temporarily store information combined together from all the ‘slaves’. Alkhalifa (2009) reported on a patient with severely impaired LTM who demonstrated STM capacity of up to 25 prose items, exceeding the capacity of both PL and VSS. This suggests the existence of an EB which holds items in working memory until they are recalled.

2. LTM/forgetting

   • Episodic memory (EM) – a form of (explicit) LTM for events occurring in an individual’s life. Endel Tulving (1972) suggested that it gives individual’s an autobiographical record of personal experiences i.e. remembering your birthday. The strength is influenced by the emotions present at the time a memory is coded i.e. traumatic events, high emotional content=recalled well. It’s also affected by the degree of processing of information at coding – highly processed=recalled more easily. It helps individuals to distinguish between real-life and delusions. Prefrontal cortex is associated with initial coding of EM, with consolidation and storage of memories associated with the neocortex. Memories of the different parts of an event are located in different areas of the brain but are connected by the hippocampus rather than having a collection of separate memories.
   • Semantic memory (SM) – type of (explicit) LTM for meanings, understandings and other concept-based knowledge. It contains all knowledge (facts, concepts, meanings etc.) an individual has learned. The strength of these is positively associated with the degree of processing occurring during coding. Semantic memories are better sustained over time than episodic ones. Semantic are linked to episodic, as new knowledge is learnt from experiences but over time, knowledge will become increasingly divorced from the event/experience it was learnt from.
   • Procedural memory (PM) – type of (implicit) LTM for the performance of particular types of action. Allows individuals to perform learned tasks with little conscious thought i.e. riding a bike. They are difficult to explain in words (non-declarative). Many occur early in life, involving the learning of important motor skills e.g. walking. It’s also involved in language, using grammar without thinking how to, showing how procedural and semantic memories work together. As it doesn’t require conscious thought, it allows people to perform other tasks simultaneously that require attention.It’s associated mainly with the neocortex brain areas of primary motor cortex, cerebellum and prefrontal cortex, and doesn’t need the hippocampus to function.
   • Forgetting - the failure to retrieve memories. Interference theory (IT) – an explanation for forgetting when similar material is confused in recall from the LTM. Information becomes confused with or disrupted by other information during coding, leading to inaccurate recall. 1. Proactive interference – works forwards in time, previously stored information interferes with an attempt to recall something new i.e. phone numbers. 2. Retroactive interference – works backwards in time, coding new information disrupts information stored previously e.g. car reg.
   • Cue-dependent forgetting (CDF) – a type of forgetting based upon a failure to retrieve the prompts that trigger recall. Information is still in LTM but cannot be accessed. Recall is dependent on upon accessing information by remembering the retrieval cue under which the information is stored. Tulving (1973) explained this as the encoding-specificity principle where recall is hindered if the context of recall is different to that at coding. The effectiveness of retrieval clues depends on how overloaded it is (fewer items associated with it=more effective), how deep the processing of the cue was and how well the cue fits the information associated with it. The two main forms of CDF are context-dependent failure and state-dependent failure.
     • Context-dependent failure – a form of CDF where recall occurs in a different external setting to coding. Occurs with external retrieval clues’, forgetting occurs when the external environment is different at recall from how it was at coding e.g. doing a test in an unfamiliar room compared to your normal classroom. Baddeley & Godden (1975) got divers to learn material on land or underwater. Recall was worse in a different context to coding than the same context, supporting CDF.
     • State-dependent failure – a form of CDF where recall occurs in a different internal setting to coding. Occurs with internal retrieval clues’, forgetting occurs when an individuals internal environment is different at recall to when the information was coded e.g. recalling information learned sober when you are drunk. Darley et al. (1973) found that PPs who hid money while high on marijuana were less able to recall where the money was when they were not high than when they were high again, providing additional support for SDF.
   • Repression is motivated forgetting where emotionally threatening events are banished into the unconscious mind to prevent feelings of anxiety they may cause. They can still affect conscious thoughts, desires and actions but they are more difficult to retrieve. Repressed memories that are ‘recovered’ during repressed memory therapy have proven to be false, a phenomenon called false memory syndrome – therapists are unwittingly suggesting and planting false memories into clients. Holmes (1990) reviewed 60 years of research and didn’t find any solid evidence of the phenomenon, weakening support for the explanation.

3. Eyewitness testimony (EWT)

   • Eyewitness testimony – evidence provided by those recalling an event who were present when the event took place. Schema – a readiness to interpret sensory information in a pre-set manner.
   • Influence of schemas: Bartlett (1932) stated that memories aren’t accurate ‘snapshots’ of events, but are ‘reconstructions’ of events, influences by active schemas, ready-made expectations based on previous experiences, moods, existing knowledge, contexts attitudes, and stereotypes. He found that when western cultural pps who were told a Navajo Indian story, ‘The War of the Ghosts’, the story didn’t make sense from their cultural viewpoint, their memory of the story became distorted, with details being changed to fit a western cultural viewpoint.
   • Factors affecting EWT include misleading information – leading questions and post-event discussion and anxiety factors. Misleading information in the form of misleading questions and post-event discussion has been found to be more able to create false memories the more believable, emotionally arousing and subtle it is. Leading questions – increase the likelihood that an individual’s schema will influence them to give them a desired answer. Post-event discussion – information added to a memory after the event has occurred.
   • Anxiety: EWT research uses artificial scenarios that have no emotional involvement for witnesses. Real-life events have high anxiety that affect recall. It ma divert attention away from important aspects of an event being witnessed. Loftus et al. (1987) argued the ‘weapons effect’, witnesses to violent crimes focus on the weapon being used rather than the offenders face so they are unable to recall important details. Yerkes-Dodson inverted-U hypothesis (IUH): Deffenbacher (1983) showed how anxiety affects the accuracy of recall. Moderate anxiety improves the detail and accuracy of memory recall up to an optimum where further anxiety causes a decline in recall. Loftus et al. (1987) found that if a person is carrying a weapon, the witness focuses on the weapon rather than the person’s face, affecting their ability to recall facial details of armed criminals, supporting the idea of anxiety diverting attention away from important features.
   • Improving the accuracy of EWT – Cognitive interview (CI): Fisher & Geiselman (1992) created a series of memory retrieval techniques.1. Change of narrative order – recall the event in a different chronological orders i.e. from end to beginning. 2. Change of perspective – recall the event from different people’s perspectives i.e. offenders point of view. 3. Mental reinstatement of context – recall environmental and emotional content of event i.e. weather and personal feelings. 4. Report everything – recall all information, even if it’s irrelevant etc. Enhanced cognitive interview (ECI) – can also be used with children. • Interviewer not distracting the witness by unnecessary interrupting/questions. • Witness controls the flow of information. • Asking open-ended questions. • Getting the witness to speak slowly. • PPS not guessing and use ‘don’t know’ instead when necessary to reduce confabulations (false memories). • Reducing anxiety in witnesses.