models of memory Flashcards
define memory
memory, a cognitive process, is a process that allows us to record, store, and later retrieve experiences and information
define STM and LTM (Atkinson and Shiffrin)
short-term memory (also called working memory): if sensory info is recognized or considered important itis coded and sent to STM, which has limited capacity (seven plus or minus two) and is supposed to last only around 12(-20) seconds.
long-term memory: if the info is rehearsed or attended to in some way it is recorded and transferred into LTM, which has unlimited capacity and may last forever.
types of long term memory
- sematic memory
- episodic
- procedural
- facial
explicit and implicit memory
explicit is conscious memory including semantic memory for facts and episodic memory for events.
implicit memory is unconscious and include procedural memory for skills, habits and learned emotional responses.
explicit memory is expressed through recollection (can be verbalized); implicit memory is expressed through performance (cannot be described).
free recall experiments
in free recall experiments, subjects are given a number of words (e.g. 20) in succession to remember and are then asked to recall them in any order (free recall). the results reliably fall into a pattern known as the serial position curve.
this curve consists of:
a) a primacy effect: subjects tend to recall the first words well, which indicates first words entered STM then to LTM due to ti rehearsal
b) an asymptote: the middle portion items of the list are remembered far less well than those at the beginning and the end.
c) a recency effect: subjects usually recall those items from the end of the list first and tend to get more of these correct on average than all the earlier items.
studies of brain damage patients
Cases of anterograde amnesia such as H.M (Milner et al) or Clive Wearing
strengths and limitations of multi-store model of memory
strengths:
- the model pioneered the new approach to memory where humans are seen as information processors
- the model’s conceptualization of memory as multi-stored is supported by research.
- it has been possible to make predictions based on the model and to design experiments.
- the overall model has been modified, for example by Baddeley and Hitch (1974) with their new version of STM, the “working memory” model.
limitations:
- the model is very simplistic and it cannot account for how the interaction between the different stores takes place.
- research into the encoding of LTM has challenged the single-store version of LTM. it is now accepted that LTM contains several stores (e.g. semantic, episodic, procedural)
define working memory model
- Baddeley and Hitch suggested the working memory model as an alternative to STM.
- this model challenged the view that STM is unitary and that information processing is passive.
- working memory is seen as an active store used to hold and manipulate information. the model has been developed over the years to include findings from research.
4 components of working memory model
- the central executive: a controlling system that monitors and coordinates the operations of the other components (slave system*). the central executive is modality free so it can process info in any sensory modality but it has limited capacity.
- the episodic buffer: a limited capacity temporary storage system of interface between the other systems in working memory. it is assumed to be controlled by the central executive through conscious awareness. the episodic buffer handles information in various modalities. the episodic buffer resembles the concept of episodic memory.
- the phonological loob: handles verbal and auditory info. it is divided into two:
- the articulatory control system: the “inner voice”
- the phonological store: the “inner ear”. this can hold speech-based material active in a phonological form. it is assumed that a memory trace can only last from 1.5 to 2 seconds if it is not refreshed by articulatory control system.
- the visuo-spatial sketchpad: the “inner eye”. This handles visual and spatial info from either sensory memory (visual info) or from LTM (images)
evidence of the working model of memory
-so-called dual tasks experiments. (Baddeley and Hitch)
strengths and limitations of working model of memory
strengths:
- the model has been useful in understanding which parts of the memory system may be linked to underlying problems in reading and mathematical skills.
- the model focuses on the processes of integrating info, rather than on the isolation of the sub-system. this provides a much better basis for understanding the more complex of executive control in working memory.
limitations:
- the major criticism of the first models of working memory was the unclear role of the central executive. This has been dealt with by including the episodic buffer in the revised model.
- the model has been criticized for its emphasis on structure rather than processing.
study 1 (multi-store model of memory)
Peterson and Peterson (1959) Short term retention of individual items.
aim: to test the hypothesis that information was held in the STM for only around 20 seconds, after that it disappears if rehearsal is prevented.
pps: 24 students
procedure: pps were tested individually. each pps was presented with 48 different consonant trigrams e.g. CHM, one at a time. right after they had heard the trigram they also heard a number e.g. 208. in order to prevent rehearsal they were instructed to count backwards in steps of three or four from that number until a signal light flashed. the light was preset to flash after 3,6,9,12 or 18 seconds. each delay period was used for 8 different syllables. as the light came on, the pps was instructed to recall the syllable and a new trigram was heard etc. number of correctly recalled trigrams was recorded.
results: the mean correctly recalled number of trigrams was directly related to the duration of the delay. The average recall was 80% after 3 seconds, this average dropped dramatically to around 10% after 19 seconds. recall decreases steadily between 2 and 18 seconds.
study 2 (multi-store model of memory)
Glanzer and Cunitz (1966) Two storage Mechanisms in free recall.
aim: to investigate the recency effect in free recall.
pps: 46 army enlisted men.
procedure: each pps was shown fifteen 15-word lists on a screen. one word appeared at a time, and each word was shown for 1 second with a 2-second’s interval between words (monosyllabic). after the last word in each list, the symbol #, or a digit from 0 to 9 was shown. if the crosshatch symbol appeared, the experimenter said “write”, and the pps immediately started writing all the words he could recall. if a number appeared the pps was to start counting out loud from that number until the experimenter said “write”. while the pps was counting, the experimenter measured wither 10 or 30 seconds with a stopwatch before telling him to write. each of the delay conditions were used with 5 of the lists. pps were tested individually. for each pps the words were assigned at random to the lists and order of the delay condition was also assigned at random. therefore, each pps received a different set of lists and a different sequence of delay conditions. after each list, pps was given 1 to 5 minutes to complete his recall of the list.
results: the mean number of correctly recalled words for each position and for each condition was calculated. 10 seconds delay reduced the recency effect and a 30 seconds delay totally eliminated the recency effect. the promacy effect was more or less unaffected by 10 second delays. for a delay of 30 there was still a clear primacy effect.
study 3 (working memory)
Hitch and Baddeley (1975) Verbal reasoning and working memory.
hypothesis: when pps perform two different tasks that require resources from the same component of working memory they will need more time compared to when they perform two tasks that require resources from two different components.
pps: 12 university students
procedure: repeated design. 32 different verbal reasoning tasks “F follows K: FK”. if two letters fit the description press a “yes” button. time it took them to make decision was recorded. sometimes the sentence was active, passive, true, false, affirmative, negative. the verb was sometimes “follow” and sometimes “proceed”. 4 different conditions: 1) repeating “the” while solving the verbal reasoning; 2) repeating “1,2,3,4,5,6” while solving the task. ; 3)repeating a random sequence of numbers like “6,5,9,3,4,8” the random sequence of numbers was varied for each task. 4)control condition (pps only had to solve the verbal reasoning task). the different conditions were given in a random order for each pps.
results: latencies were shortest for the control condition and longest for the condition with a random sequence of numbers. for the other two conditions the “the” condition had a shorter latency than the “1,2,3,4,5,6” condition.
study 4 (working memory)
Strayer and Johnston (2001) Dual-task studies of simulated driving and conversing on a cellular telephone.
aim: to investigate whether talking on the phone affects attention in a simulation of driving.
pps:48 students (24 male 24 female) aged 18 to 30. pps had normal vision and received a perfect score on a color blindness test. three groups: radio control, handheld phone, and hands-free phone.
procedure: task: pps were equipped with a joystick and asked to manoeuvre the cursor on a computer display to keep it aligned as closely as possible to a moving target. the movement was smooth but unpredictable. at intervals the target flashed red or green. as it flashed red they were to press a “brake button” on the joystick. the first 7 minutes was a warm-up period. then followed a 7.5 min phase when pps only tracked the target. during the next 15 min pps tracked the target while doing another task. the final 7.5 min they again only tracked the target.
additional task: radio control. two groups pps had a conversation with a confederate over the phone. the conversation was either over the Clinton presidential impeachment, or salt lake city Olympic committee bribery scandal. in one group a handheld phone was used, in the other a hands-free phone was used. number of misses, i.e. failures to “brake”, were counted. reaction times were also recorded.
results: pps in the two phone groups made more misses and they also had slower reaction times. the researchers found no significant differences between the groups with handheld and hands-free phones.
