The document summarizes several studies investigating short-term memory (STM) and long-term memory (LTM). One study found that lists of words that were acoustically or semantically similar were recalled worst from STM and LTM respectively, suggesting STM encodes information based on sound and LTM based on meaning. Another study found the capacity of STM is around 7 items and its duration is less than 30 seconds without rehearsal. A long-term study found very long-term memories can last many years with little decline over time.

1. Since list C was recalled the worst, it appears that there’s semantic STM Baddeley (1966)
Encoding in confusion in LTM. Therefore, LTM tends to be encoded on a semantic basis.
The Multi-Store Model
Short-Term Memory Atkinson and Shiffrin (1969) Long Term Memory
Three Separate Stores For Memory. (Sensory, Short-Term and Long-term Memory)
Information Is Encoded Acoustically Information is Encoded
(Through Sound) Encoding in STM and LTM by Baddley (1966)
Semantically
Aim: To investigate how information is encoded in STM and LTM memory.
Procedures: Participants were present with four word lists which are either: (Through Meaning)
List A: acoustically similar (cat, mad, sat, sad)
List B: acoustically dissimilar (pen, day, cow)
List C: semantically similar (big, huge, great)
List D: semantically dissimilar (old, late, thin)
75 participants heard one list repeated four times. Immediately after this (to test STM) and 20 minutes
later (to test LTM) , they were given a list in both occassions that contained all the words but in the
wrong order. There task was to rearrange the words in the correct order.
Findings: Those participants given list A (acoustically similar) performed the worst (recall 10%). Recall
for the other lists were comparatively good (60-80%) .
Those participants given list C (semantically similar) performed the worst. Recall for the other lists was
Capacity is on average 7 items comparatively good (70-85%)
(+/-2) Has Unlimited Capacity
Conclusion: Since List A was recalled the worst, it would appear that there’s acoustic confusion in
STM. Therefore, STM tends to be encoded on a acoustic basis.
Since list C was recalled the worst, it appears that there’s semantic confusion in LTM. Therefore, LTM
tends to be encoded on a semantic basis.
Capacity in STM Jacobs 1887
Duration in LTM by Bahrick
Aim: to investigate the capacity of STM
Procedures: Jacobs reads aloud lists of either et al (1975) Duration a long time…
letters or numbers. He gradually increased the
but declines a little over time.
Duration less than 30 seconds length of these lists until participants could only
successfully recall them 50% of the time.
Jacobs used a wide range in his sample. Aim: To investigate the existence of very long
Findings: STM capacity for numbers was 9, term memories (VLTM) using real-life
whereas for letters it was 7 memories.
Procedures: 400 participants ranging in age
After 18secs, Conclusion: STM has a limited capacity of
from 17 to 74 were asked to remember the
fewer than 10% between 5 and 9 names of classmates from their high school (a
recalled free recall task). They were also shown a set of
correctly. Duration in STM (1959) photos and a list of names, some of which
were of their ex-school friends. They had to
After only Aim: To investigate the duration of STM when no rehearsal is allowed.
identify their ex-school friends (a recognition R e h e a rsa l
Procedures: Participant were read a nonsense trigram (three
3secs, 80%
consonants with no meaning e.g.LTB). Immediately after this, task). Loop
recalled participants had to count backwards in threes starting from a very Findings: Those who’d left high school within
correctly. large three digit number (e.g. 576) for a specified period of time. This the previous 15 years recalled 90% of the
time period was called a retention interval and varied from 3-18
faces and name in the recognition task. Those A tte n t io n
seconds. The counting backwards was called the distracter task. It
was designed to prevent rehearsal of the trigrams. At the sound of a who’d left 48 years previously recalled 80% of
tone, participants had to recall the trigram. the names and 70% of faces. Free recall of the
Findings: Approximately 90% of the trigrams were recalled after a 3
names was comparatively poor.
Recall got progressively second retention interval. Only about 10% were recalled after 18
seconds. Letters had to be exactly in the same place in the recalled Conclusion: people do possess VLTM (very
worse as the delay trigram as in the original. long-term memories), although these decline a
S e n so ry S h o rt T e rm Lo n g T e rm
Conclusion: Without rehearsal, the duration of STM is very short little over time.
grew longer! M e m o ry
indeed (less than 18 seconds)
M e m o ry M e m o ry
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