Models are theories based on information processing systems which explain how memory works. A number of models have been put forward. Multi store model :
Atkinson and Shiffrin 1968- structural model, flows through stores in a fixed linear sequence.
Environmental Stimuli-> SM-> Attention->STM(Maintenance Rehearsal)(Information Retrieval)->Elaborate Rehearsal(Retrieval)-> LTM
Sensory memory is a set of limited capacity, modality, specific stores that hold information for a very brief period of time.
Sperling 1960- tested iconic memory, grids of letter, 50 milliseconds, people could retain four items up to one second.
Sensory memory can hold items for up to two seconds, it's passively registered.
Only a fraction of items are passed into STM.
Short Term Memory
Short term memory is a temporary store where small amount of information can be stored for brief periods, it's a fragile store, information can be easily lost.
Displacement is a type of forgetting where the items currently in the limited capacity STM are pushed out before being transferred to LTM to make room for incoming items.
Jacobs 1887 tested capacity, digit span technique- where digits increase in a sequence, numbers, monotone, equal space, repeat immediately after in correct order, average capacity of 7 items.
Miller 1956 increase capacity by chunking things together.
Simon 1974 capacity is smaller for large chunks than for smaller chunks.
Peterson and Peterson 1959 tested duration using trigrams which are groups of three unrelated consonants, repeat after increasing time of interval, the longer the time between learning and recall, more trigrams were lost. Average 6-12 seconds. Criticised as can't rule out influence of limited capacity, same participants were used for earlier trials of trigrams, could interfere with processing new ones.
Conrad 1964 encoding,participants substituted letters which sound alike rather than look alike when letters were presented visually acoustic encoding.E,how information is represented,D,how long it lasts,C,how much it holds
Long Term Memory
Long Term Memory is a permanent store where limitless amounts of information can be stored.
Interference is a type of forgetting where information stored in LTM is confused with similar information.
Bahrick et al 1975 tested duration, photographs, classmates, did well up to 34 years later, did well photo to name rather than just recall names. Declined in performance after 47 years, used meaningful stimulus, semantically. Decline in memory from age or limits in LTM duration.
Baddeley et al 1966 encoding is meant to be semantic, participants made errors when reading lists of semantically similar compared to dissimilar. Even though it can use acoustic or visual coding as well.
Free recall of words, word is plotted against its position in the list, characteristic serial curve is produced. Words at the beginning go to LTM, primacy effect, words in the middle are forgotten, asymptote, words at the end go to STM, recency effect.
Glanzer and Cunitz 1966 gave participants a distractor task, the recency part was lost while the primacy remained unaffected, two separate stores.
Milner 1966 HM, neurophysiological, remove his hippocampus to try cure his epilepsy, left him with severe anterograde amnesia.
Blakemore 1988 describes his memory for new events, face, places, numbers as it settles in his mind for a few seconds, it then goes.
Squire et al 1992 PET brain scans, pre frontal cortex active during STM tasks, hippocampus active during LTM.
Strengths of the multi store model are that it's an important contribution to memory research and has provided a foundation for future work on memory.
Weakness of the multi store model are that it's oversimplified, takes no account of LTM activation or storage information.
Multi Store Model
Shallice and Warrington 1970 KF, suffered from brain damage from a motorcycle accident, impaired his STM, LTM intact, predict LTM must pass through STM, goes against this idea.
Ruchkin et al 1999- participants when recalling pseudo(nonsense) words, was different, when processing words, they were activating information stored in LTM. Suggesting LTM must be activated before certain stages of STM processing can occur.
Craik and Lockhart 1972 best way to remember in LTM is semantically rather than repetition.
Brown and Kulik 1977memories of events which were highly emotionally charged or personally significant are imprinted in LTM, flash bulb memory.
Working Memory Model
Central Executive-Phonological Loop, Episodic Buffer, Visuo spatial sketchpad-Long Term Memory.
Baddeley and Hitch 1974 STM is an active store used to hold information from sensory memory and LTM whilst it's being manipulated, involved in reasoning, understanding and learning.
Central executive- attention, Visuo spatial sketpach- inner eye, visual cache, shape, colour, Phonological loop- inner voice, articulatory loop, phonological store.
Baddeley et al 1975 participants couldn't correctly identify top or bottom angles of imagined capital letters at the same time as performing a light tracking task, both use visuo spatial sketchpad. Had no problem with the tracking task at the same time as a verbal task, separate components each have limited capacity.
Klauer and Zheo 2004 more activity on the left side of the brain when performing visual, more on the right when performing spacial, separate subsystems within visuo spatial sketchpad.
Bunge et al 2000 greater activity in the pre frontal cortex when performing two working tasks rather than one, central executive works harder to allocate resources in dual task conditions.
Strengths and Weakness
Strengths of the working memory model, more flexible model which looks at both temporary storage of information and active processing, can account for findings.
Weakness of the working memory model, remains difficult to test central executive precisely, concentrates on STM doesn't offer a complete understanding of how memory works.
Engle et al 1999 capacity has been shown to be linked to reading comprehension and note taking, and phonological loop deficit has been identified an underlying factor of children with dyslexia.