working memory Flashcards
what is working memory
- “Working memory refers to the system or systems that are assumed to be necessary in order to keep things in mind while performing complex tasks such as reasoning, comprehension and learning.” (Baddeley, 2010)
- Also not-so-complex things - like thinking and daydreaming.
modal model of memory
- Atkinson and Shiffrin, 1968
- “Modal” model of memory.
- Multiple memory stores.
- Information passes between the stores via attention, encoding and retrieval.
- Information maintained in the STS via rehearsal.
problems with the modal
- There is only one short-term store (STS) - how can you do two things at once?
- The amount of time items spend in the STS dictates how well they are stores in long-term memory.
- Patients were found that have selective damage to the STS but no major difficulties with comprehension, problem solving, general intelligence, etc.
baddeley’s working model of memory
- Worked on this at Sussex university
- Different types of loops, that hold different types of information, that are held by the central executive.
capacity of the phonological loop
- Used with sound.
- The phonological loop can hold, if tested using unrelated words, digits, letters, etc, around 7 items of information.
- Word length effect - Baddeley et al., 1975:
- Presented lists of 5 words to write down in order
- List A - some, harm, bond, yield, hate
- List B - …
- List C - …
- List D - …
- List E - association, considerable, representative, individual, immediately
- Correct recall related to number of syllables.
- Strong correlation between reading and correct recall.
· People only remember what they can say in around 1.5 secs.
· To remember words or numbers people will generally repeat them to themselves (under their breath - “sub-vocally”).
- This is done via an “articulatory loop”.
the visualspatial sketchpad
· Functions - sequences of visually guided actions, and seeing things “in the mind’s eye”.
· Similar to the phonological loop, the capacity of the visuaspatial sketchpad appears around 6-7 items.
· Some have argued the visuospatial sketchpad can contain a fixed number of items (e.g., 4 or 7).
- Others have argued working memory is a limited resource which is shared between all items.
baddeleys working model of memory 2
· We have dedicated working memory “buffers” for some specialised types of information.
· These buffers are independent.
· Information held in one buffer does not interfere with another, e.g., we can juggle as well as hold a string of digits in mind.
· The buffers are thought to be controlled by a “central executive”.
· The “capacity” of these buffers depends on what is being stored.
- Brain damage can result in damage to these buffers.
problems with the model
· People are able to repeat back meaningful sentences and paragraphs far better than unrelated words.
· Baddeley and Wilson (2002):
· Tested 23 “amnesic patients”
· Found many examples where immediate prose recall was normal.
· Recall after a delay was highly impaired.
- “While this pattern might not surprise an experienced clinician, it does present a problem for the version of the working memory model proposed by Baddeley”.
episodic buffer - features
· A limited-capacity temporary storage system that is capable of integrating information from a variety of sources.
· Episodic in the sense that it holds episodes whereby information in integrated across space and time.
- Plays an important role in feeding information into and retrieving information from episodic long-term memory.
evidence for reactivation of episodic information
· Bird et al, (2014) - watch a sequence of videos in while in an MRI scanner, and then recall the videos in the MRI scanner.
· Episodic information (an event unfolding over time) activates widespread regions of the brain.
· These activation patterns are event specific.
· Same patterns of activity are reactivated whenever an event is retrieved.
- The “holding in mind” of the main features of the event involves something like the episodic buffer.
a newer perspective
· Hierarchical process view (Hasson et al, 2015).
· Most working memory models separate ongoing information processing (attending to what’s around us) from information that we are holding in mind.
· But ongoing information processing requires us to accumulate information over time.
- This happens over different timescales in different brain circuits.
summary
· Working memory is such a big concept it’s unlikely that there can be a single “model” of it.
· Specific buffers have specific purposes, but understanding one may not help us understand other aspects of working memory.
- The hierarchical process view addresses how working memory supports ongoing information processing - but what about when reasoning or problem solving?
