S1W8- Memory

S1W8- Memory

1. Types of memory

   • Implicit (Procedural)
     • “implicit” memory refers to learning that take place without our awareness Or skills that may have been learned with awareness, but are now performed without (procedural). A common way to test procedural memory is by using the Serial Reaction Time Task
       • Serial Reaction time task
         • -Shape appears in one of 4 locations, participant has to press a corresponding button as soon as possible -This repeats, with the shape (often an asterisk) appearing in different positions in random order . -RT for baseline (random) blocks is likely to decrease a little over time due to practice RT for implicit blocks will decrease significantly more due to implicit sequence learning
           • Neural correlates of the serial reaction time task have implicated the basal ganglia – especially the Striatum.
     • Declarative Memory and the Hippocampus
       • Whereas the basal ganglia is important for procedural memory, the medial temporal lobe (MTL) is crucial for declarative memory (episodic, autobiographical, semantic). Perhaps the most important structure is the Hippocampus This is where memories change from being short-term to being long-term This is called Consolidation
         • Consolidation is affected by a variety of factors: -The depth of stimulus processing. Deeper and more elaborate initial processing leads to stronger memories (Craik and Lockhart, 1972) - Distinctiveness – more distinctive information is better remembered Relevance – personally relevant information (i.e. about themselves, or something they are interested in) will be better remembered - Emotionality – emotional stimuli are automatically processed more deeply than neutral stimuli
           • Emotional Memory: -Stressful or emotionally exciting experiences increase the secretion of adrenaline (aka epinephrine) and cortisol. -Greater processing of negative or threat related information has a clear evolutionary advantage, as it would allow for better avoidance of dangerous situations.
             • Consolidation isn’t a one-off event, we also have re-consolidation When a memory is reactivated (retrieved/remembered), it is brought into a labile state In this labile state it is fragile, or malleable
   • Explicit (Declarative)
     • Declarative memory consists of facts and events that can be consciously recalled or "declared."
       • The other component of declarative memory is semantic memory, which is the ability to recall facts and concepts, often referred to as common knowledge.
   • Evidence supporting the STM/LTM division
     • STM has limited capacity (approximately 7+-2 items); LTM has none that we know of
       • When something is forgotten from STM it is lost forever; when something is forgotten from LTM it can be retrieved with hints
   • Sleep, exercise and memory
     • Both declarative and procedural memory are improved by sleep
       • Compared with a period of wakefulness of equal length, a period of post-learning sleep enhances retention of declarative (mainly episodic) information and improved non-declarative procedural performance

2. Forgetting

   • Clinical Forgetting: Amnesia
     • - Damage to the hippocampus can completely destroy explicit memory/ Clive Wearing’s hippocampi were destroyed as a result of herpes simplex encephalitis, leaving him with anterograde amnesia
     • Korsakoff’s Syndrome
       • Normally result of long-term alcoholism
         • 6 major symptoms: types of amnesia.
     • Patient H.M (1926-2008)
       • - His attention and working-memory capacities were normal; he could hold items in mind while actively rehearsing them He could not consolidate and store this information in LTM; he was able to carry out a conversation, but several minutes later would be unable to remember having had the exchange, or who he had spoken to However - although he couldn’t create new explicit memories, his implicit memory remained intact
   • Non- Clinical Psychology
     • McGeoch (1932) – trace decay theories are invalid because time itself is not a causal agent. McGeoch thus argued from this that interference is the only true forgetting mechanism.
     • Interference
       • - Memories acquired on different occasions interfere with eachother -The similarity between the memories affects interference
         • -Retroactive interference – acting backwards -Proactive interference – acting forwards
     • Directed Forgetting
       • A phenomenon involving impaired long-term memory triggered by instructions to forget information that has been presented for learning. It allows us to see how we can intentionally control our memory, to look at neural differences in responding to intentionally compared to unintentionally forgotten material
         • The Directed Forgetting (DF) paradigm (MacLeod, 1989) - Two phases
           • Study Phase: Participants are shown a series of words or pictures which they are instructed to either remember or forget
             • Test Phase: Participants are tested on their recognition of study words (indicate whether a word or picture is old or new) or their free recall of the study words
               • A Directed Forgetting Effect (DFE) is then calculated to see how much memory was enhanced for the words instructed to be remembered This is done by taking away the number of to-be-forgotten words that were remembered (TBF-R) from the number of to-be-remembered words that were remembered (TBR-R)
       • Mechanisms of Directed Forgetting
         • Selective Rehearsal: TBR items are subjected to more elaborative processing and more repeated rehearsal than items instructed to be forgotten. TBR memory traces are strengthened, while TBR traces are more likely to passively decay (Basden, 1993)
         • Active Suppression : TBF instruction leads to recruitment of inhibitory mechanisms which terminate further processing of TBF items, and suppress their memory to below-baseline levels (Levy & Anderson, 2002)