Short And Long Term Memory Flashcards
Capacity
Amount of info held in a memory store
Capacity of short term memory
Limited
5-9 items
Capacity of long term memory
Unlimited
Years
Jacobs STM 1887
Investigate capacity of STM using digital spam technique / 443 females (8-19) Repeat back string of numbers or letter in same order and amount of items given increased until participant does no more / Average of 7.3 letters and 9.3 numbers / Supports millers notion of 7+/-2
Chunking
Where you split big pieces of information into smaller chunks so that it’s easier to remember
Jacobs investigation strengths
Lab experiment
Less extraneous variables
Other studies have similar answers which increased validity
Jacobs investigation weakness
Conducted a long time ago
-results might not be valid as there were confounding variables that were not controlled
Duration
Length of time the information can be held in the memory
Duration of short term memory
18-30s
Duration of ltm
Potential lifetime
Peterson and Peterson 1959
Investigate duration of stm / 24 uni students, 3 letter consonant nonsense syllable followed by a 3 digit number. Asked to count backwards in 3s or 4s to prevent reversing nonsense syllable 2 practice trails, 8 real trials / 90% remembered when 3s interval 2% remembered when 18s interval / Longer you wait more you forget
Bahrick 1975
Duration of long term memory
/
392 people from Ohio, 17-74
Lost names of ex classmates ( free recall)
Shown photos then asked to name ( photo recognition)
Given names and match photos ( name recognition test)
/
15 years of leaving school - 90% remembered on name and faces
60% free recall
After 30years, went down to 30% accuracy
After 48 years, name recognition 70%, photo recognition 40%
/
Recognition better that recall
Huge store of info but might need cues to access it
Strength of bahrick investigation
High external validity-applied to real world
Weakness of bahrick investigation
Harder to control confounding variable when using real life stimulus
Peterson and Peterson strength
Lab experiment
Highly controlled
Peterson and Peterson weakness
Meaningless in real world as stimuli was artificial
Coding
The way information is hanged so that it can be stored in the memory
Info enters brain via senses but stored in different forms
Coding in short term memory
Acoustic
Coding in long term memory
Semantic
Baddeley 1966 aim
To test whether acoustic coding( sound of the word) is used in short term memory whereas Semantic coding in LTM
Baddeley procedure
Lab experiment
Condition 1) acoustically similar ( meet feet sweet)
Condition 2) semantically similar (neat clean tidy)
Condition 3) acoustically dissimilar ( hot far jam) CONTROL
Condition 4) semantically dissimilar ( pen jump day) CONTROL
Variables changed were AS/AD and SS/SD
variable measured were number of errors
Asked to serial recall either immediately for STM or 20mins later LTM
Baddeley finding
Immediate recall- more errors on AS list then on AD list
No difference between SS and DS words
Delayed recall - more errors on SS list then SD. No difference between AS and DS
Baddeley conclusions
Nature of encoding is different for LTM and STM
STM- acoustically encoded, semantics not important
LTM-semantically encoded, acoustics not playing important role
Baddeley strengths
Lab experiment
Controlled