Encoding, capacity, and duration (AO1) Flashcards
Define ‘encoding’.
How sensory input is formatted (which sense) by the memory system
Define ‘capacity’.
How much information can be stored
Define ‘duration’.
How long the information can be held in storage
What are the 5 studies that support the encoding, duration and capacity of the STM and LTM?
Encoding - Baddeley (1966)
Capacity:
STM - Miller (1956)
LTM - Brady (2008)
Duration:
STM - Peterson and Peterson (1959)
LTM - Bahrick et al (1975)
How does Miller (1956) provide evidence for the STM’s capacity? (4 points)
Using a tachistoscope, participants were presented with an increasingly long sequence of digits that they had to report back in order
Mean digit span:
Numbers - 9.3
Letters - 7.3
Observed that pictures or information tend to come in 7
Average person can hold 5-9 items in their STM
How does Brady (2008) provide evidence for the LTM’s capacity? (5 points)
Showed 2500 objects over 5.5 hours
Later shown pairs of objects and were asked to identify which of the two they had seen
Novel object choice - 92% correct
Exemplar object - 88% correct
Different angle - 87% correct
What were the 1 advantage and 2 disadvantages of Brady’s investigation of the LTM’s capacity?
Advantages:
High internal validity - situational variables controlled
Disadvantages:
Low task validity - artificial stimulus material which people don’t tend to do in real-life activities used
Lowered internal validity - confounding variables (eg. how meaningful pictures were to participants) not controlled
How does Peterson and Peterson (1959) provide evidence for the STM’s duration? (4 points)
Participants were asked to remember a trigram, a single nonsense syllable of three consonants
They were then given an interference task to prevent rehearsal (eg. counting backwards in 3s from 100) before testing their recall after 3-18 seconds
Percentage of people who correctly recalled the trigram:
3 seconds - 90%
9 seconds - 20%
18 seconds - 2%
STM duration is up to 30 seconds
How does Bahrick et al (1975) provide evidence for the LTM’s duration? (5 points)
American ex-high school students aged 17-74 tested for recall of classmates
3 tests: Free recall, name recognition, and recognition of photos
Participants could still recall memories well up to 34 years
After 47 years, there was a dip in their recall
Duration of LTM - potentially unlimited
What was the advantage and disadvantage of Bahrick et al’s study of the LTM’s duration?
Advantages
High ecological validity - used a naturally occurring form of info, thus avoiding the artificiality often present in memory studies
Disadvantages
Low internal validity - confounding variables like how often participants may have referred back to their yearbook not controlled
What was the strength and 2 weaknesses of all of the studies about STM?
Strength: High internal validity
Confounding variables such as noise and distraction were the same for all participants
Weakness: Low ecological and task validity
Task - artificial stimulus material which people don’t tend to do in real-life activities used
Ecological - controlled lab experiment
