Coding, capacity and duration of memory

Question 1

What is short term memory?

Answer 1

The limited capacity memory store. In STM, coding is mainly acoustic (sounds), capacity is between 5 and 9 items on average, duration is 18-30 seconds

Question 2

What is long term memory?

Answer 2

The permanent memory store. In LTM, coding is mainly semantic (meaning), it has unlimited capacity and can store memories for up to a lifetime

Question 3

What is coding?

Answer 3

The format in which information is stored in the various memory stores

Question 4

What is capacity?

Answer 4

The amount of information that can be held in a memory store

Question 5

What is duration?

Answer 5

The length of time information can be held in memory

Question 6

What did Baddeley do to research coding?

Answer 6

Gave different lists of words to four groups of participants to remember

Question 7

What were the four groups in Baddeley’s study?

Answer 7

Acoustically similar
Acoustically dissimilar
Semantically similar
Semantically dissimilar

Question 8

What was the method of Baddeley’s study?

Answer 8

Participants were shown the original words and asked to recall them in the correct order.

Question 9

What were the results of Baddeley’s study?

Answer 9

When participants did the task immediately, recalling from short term memory, they tended to do worse with acoustically similar words. When they recalled the word list after a time interval of 20 minutes, recalling from long term memory, they did worse with the semantically similar words.

Question 10

What can we conclude from Baddeley’s study?

Answer 10

The findings suggest that information is coded acoustically in short term memory and semantically in long term memory

Question 11

What did Joseph Jacobs (1887) measure - what does this mean?

Answer 11

Measured digit span - how much information can STM hold at one time

Question 12

What was the method for digit span study?

Answer 12

The researcher reads out four digits and the participant recalls these out loud in the correct order. If this is correct the researcher reads out five digits and so on until the participant cannot recall the order correctly - this indicates the individuals digit span

Question 13

What did Jacobs find for the mean span for digits and letters?

Answer 13

Mean for digits was 9.3 items. Mean for letters was 7.3

Question 14

What did Miller observe about span of memory? What did this lead him to think?

Answer 14

Noted that things often come in sevens (days of the week, deadly sins etc). Lead him to think that the span of STM is about 7 items.

Question 15

What did Miller note about chunking?

Answer 15

People can recall five words as easy as they can recall five letters. We do this by chunking - grouping sets of digits or letters into units or chunks.

Question 16

What was the method of Peterson and Peterson’s study of duration of STM?

Answer 16

Tested 24 students in 8 trials each. On each trial the student was given a consonant syllable (such as YCG) to remember. Also given a 3 digit number. The student counted backwards from this number until they were told to stop. The counting backwards was to prevent any mental rehearsal of the consonant syllable. On each trial they were told to stop after varying periods of time: 3, 6, 9, 12, 15, 18.

Question 17

What were the findings of Peterson and Peterson’s study?

Answer 17

After 3 seconds, average recall was 80%. After 18 seconds, it was about 3%.

Question 18

What did Peterson and Peterson’s study conclude?

Answer 18

STM duration might be about 18 seconds, unless we repeat the information over and over

Question 19

What was the method of Bahrick’s study into duration of LTM?

Answer 19

Studied 392 American participants aged between 17 and 74. High school yearbooks were obtained from the participants or directly from some schools. Recall was tested in various ways, including: (1) photo recognition test consisting of 50 photos, some from the participants’ high school yearbooks, (2) free recall test where participants recalled all the names of their graduating class

Question 20

What were the results of Bahrick’s study?

Answer 20

Participants tested within 15 years of graduation were about 90% accurate in photo recognition. After 48 years, recall declined to about 70% for photo recognition. Free recall was less accurate than recognition - about 60% after 15 years, dropping to 30% after 48 years.

Question 21

What can we conclude from Bahrick’s study?

Answer 21

LTM may last for up to a lifetime for some material

Question 22

What is a limitation of Baddeley’s study?

Answer 22

Used quite artificial stimuli rather than meaningful material.
Word lists had no personal meaning to participants - lacks mundane realism.
Findings from the study may have limited application

Question 23

What is a strength of Baddeley’s study?

Answer 23

Identified a clear difference between two memory stores
Idea that STM uses mostly acoustic coding and LTM mostly semantic has stood the test of time
Important step in understanding the memory system

Question 24

What is a strength of Jacobs’ study?

Answer 24

It has been replicated
Original study lacked adequate controls. Eg. Many participants may have been distracted during testing (confounding variable). However, Jacobs’ findings have been confirmed by other better controlled studies since (eg. Bopp and Verhaeghen 2005)
Suggests that Jacobs’ study is a valid test of digit span in STM

Question 25

What is a limitation of Miller’s research?

Answer 25

May have overestimated STM capacity
Cowan (2001) reviewed other research and concluded that the capacity of STM is only about 4+-1 chunks
Suggests that lower end of Miller’s estimate (5 items) is more appropriate than 7

Question 26

What is a limitation of Peterson and Peterson’s study?

Answer 26

Stimulus material was artificial
Recalling consonant syllables does not reflect most everyday memory activities where what we are trying to remember is meaningful
Study lacked external validity

Question 27

What is a strength of Bahrick’s study?

Answer 27

High external validity
Researchers investigated meaningful memories.
‘Real’ estimate of the duration of LTM