Short Term and Long Term Memory (Week 10)

Memory

the retention, retrieval and use of information after the information source is no longer available

Clive Wearing

• profound case of amnesia due to disease

• damage to hippocampus

• inability to form lasting memories

• 7-30 seconds he could remember

• Restarting conscience

Modal Model of memory

• Atkison and Shifrin (1968)

• Computer as a model of cognition

• Memory is and integrated system that processes information

• Acquire through sensory memory → store short term than long term → retrieve

• components of memory do not act in isolation

Sensory Memory

• Short lived

• registers all or mot information that hits our sensory receptors

• information decays very quickly

Persistence of vision

• the retention of a visual stimulus for fractions of a second after it is no longer visible

• Retention of the perception of light

  • fills in frames in a film

Persistence of auditory

• persistent in the mind

• hear someone say something and then figure it out

Sensory memory capacity

Short can be increased with tone

Sensory memory purpose

• collects information to be processed

• Holds information for initial processing

• Filling the blanks when stimulation is intermittent

  • continuation of experiences like blinking

Short term memory

• System involved in storing small amounts of information for a brief period of time

• Window on the present

• 5-9 items for 15-20 seconds

• short storage to decide what to do with it

STM capacity

seven plus or minus two tested using digit span can be increased using chunking

Chunking

Small units can be combined into larger meaningful units

enables limited capacity to deal with large amounts of information involved in many things

Chunk

a collection of elements strongly associated with one another but weakly associated with other elements

Limit of STM

• is a limit to chunking → bigger the chunk less amount of chunks

• More complex amount of information obtained became less

• The complexity of the item also is important into the capacity of stm

Physiological structure of short term memory

stimulus is represented by the firing of neurons

Mental structure of STM

Auditory, visual and semantic coding

Difference between stm and wm

STM hold information for a brief period of time, and working memory manipulates information

Working memory (WM)

A limited capacity system for temporary storage and manipulation of information for complex tasks such as comprehension, learning and reasoning

Working memory modal

• Central executive

• phonological loop

• visuospatial sketchpad

• Episodic buffer

Phonological loop

Includes verbal and auditory information has two components phonological store and articulatory control process

Phonological store

• holds about 2 s of auditory information

• a short tape loop on which you can copy auditory information

• enter from the environment

Articulatory control process

• talking to yourself

• used to refresh information that is already in the phonological store to keep it from fading

Phonological similarity effect

• letters or words that sound similar can be confused

• similar sounding letters not similar looking letters

Word length effect

• memory for a list of words is better for short words than long words

• how long it takes to say the words

Articulatory suppression

preventing rehearsal impairs working memory for verbal material

Central executive

• Attention controller

  • focous, divide, switch attention

• Co-ordinate's the two components so they can work together

• controls suppression of irrelevan

Episodic buffer

• Was added later to address the limitations of the original model

• backup store that communicates with wm and ltm components

• holds information longer and has greater capacity than the other two components pho and vis

Visuospatial sketchpad

• medium to keep visual or spatial information active

Are visual and spatial information organised separately

• If true then the visual interfering task (colour discrimination) should disrupt memory for visual stimuli (ideographs) but have less impact on memory for the spatial stimuli (dot location)

• and vice versa for the spatial interference task

• Results supported this prediction

• Neuroscientific data also indicates separate brain locations for visual and spatial memory

  • brain damaged patients and neuroimaging studies

Brain for WM

• Hippocampus

  • know from damage

  • important in transfer of memory

• Amygdala

  • emotional

• Visual

• Frontal lobe

• Neurons

  • memory stored in activation of neurons

• Dissociations/brain damage

  • how damage to or removal of the prefrontal cortex affects the ability to remember for short periods of time

Long term memory

• The information we have learned and stored experiences of our lives

• anything that has happened past 30 seconds

• Memories fade over time; more recent memories are more detailed

• Rehearsal helps transfer info into LTM but it isn’t essential

Serial position effect

memory is better information presented at the beginning (primacy effect - ltm) and at the end (recency effect - stm)

Coding

• the form in which stimuli are represented

• Physiological

  • how the stimulus is represented by the firing of neurons

• Mental

  • how stimulus or experience is represented in the mind

Visual coding STM

Holding an image in our mind that we need to remember

Visual coding LTM

Visualising a person, place from our past

Auditory coding STM

Representing the sounds of letters in the mind just after hearing them

Auditory coding LTM

Playing a song in our mind over and over

Semantic coding STM

Placing words in a STM task into categories based on meaning

Semantic coding LTM

Recalling the general plot of a movie you saw last week

Proactive interference

occurs when information learned previously interferes with learning new information

A interferes with B

Retroactive interference

• When new learning interferes with remembering old learning

• B interferes with A

Recognition memory

• identification of a previously encountered stimulus

• e.g. multiple choice

Recall

• the generation of a previously encountered stimulus

• e.g. short answer

Hippocampus

responsible for one’s ability to encode new long term memory

H.M. case study

• surgery for epilepsy removal of the hippocampus

• stm intact but could not form new long term memories

K.F. case study

• brain injury to parietal lobe in a motorbike accident

  • opposite of H.M

  • stm bad, ltm good

Double Dissociation

evidence of brain areas doing different things

Retrograde amnesia

• loss of memory for events prior to the trauma

• not a linear nocking out of past memories

Graded amnesia

memory for recent events is more fragile than for remote events

Types of long term memory

Explicit and Implicit

Explicit memory

Conscious includes episodic, and semantic

Episodic memory

personal events

Semantic memory

Facts and knowledge

Interaction between episodic and semantic memory

• Episodic lost

  • acquiring knowledge may start as episodic than fade to semantic

• Semantic can be enhanced if associated with episodic

  • Autobiographical memory

    • specific experiences includes semantic and episodic components

    • Personal semantic memories

    • knowledge can influence what we experience determining what we attend to

Implicit

not conscious includes procedural memory, priming and conditioning

Procedural memory

• skill memory

• riding a bike, playing an instrument, kicking a ball,

• muscle memory

Priming

• responses change from previous experience

• Presentation of a stimulus has an effect that continues when the stimulus is no longer present. and the continuing effect makes the response to the next presentation of the stimulus faster or more accurate

Effect of time on memory

typical research findings suggest that forgetting increases with longer intervals from the original encoding

Episodic future thinking

• create episodic memory like simulations of possible future events

• These thoughts combine semantic knowledge and episodic memory elements to enable us to imagine possible personal future scenarios

• similarities to episodic memory - need to think about past to think about the future

How is memory impacted

• Brain damage

• time

• age

• disease