Coding, capacity and duration of memory Flashcards
What is short term memory?
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
What is long term memory?
The permanent memory store. In LTM, coding is mainly semantic (meaning), it has unlimited capacity and can store memories for up to a lifetime
What is coding?
The format in which information is stored in the various memory stores
What is capacity?
The amount of information that can be held in a memory store
What is duration?
The length of time information can be held in memory
What did Baddeley do to research coding?
Gave different lists of words to four groups of participants to remember
What were the four groups in Baddeley’s study?
Acoustically similar
Acoustically dissimilar
Semantically similar
Semantically dissimilar
What was the method of Baddeley’s study?
Participants were shown the original words and asked to recall them in the correct order.
What were the results of Baddeley’s study?
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.
What can we conclude from Baddeley’s study?
The findings suggest that information is coded acoustically in short term memory and semantically in long term memory
What did Joseph Jacobs (1887) measure - what does this mean?
Measured digit span - how much information can STM hold at one time
What was the method for digit span study?
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
What did Jacobs find for the mean span for digits and letters?
Mean for digits was 9.3 items. Mean for letters was 7.3
What did Miller observe about span of memory? What did this lead him to think?
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.
What did Miller note about chunking?
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.
What was the method of Peterson and Peterson’s study of duration of STM?
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.
What were the findings of Peterson and Peterson’s study?
After 3 seconds, average recall was 80%. After 18 seconds, it was about 3%.
What did Peterson and Peterson’s study conclude?
STM duration might be about 18 seconds, unless we repeat the information over and over
What was the method of Bahrick’s study into duration of LTM?
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
What were the results of Bahrick’s study?
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.
What can we conclude from Bahrick’s study?
LTM may last for up to a lifetime for some material
What is a limitation of Baddeley’s study?
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
What is a strength of Baddeley’s study?
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
What is a strength of Jacobs’ study?
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
