Coding, capacity and duration Flashcards
What are the two main types of memory?
Short term and long term memory
What is short term memory?
The limited capacity memory store. Coding is mainly acoustic (sounds), capacity is 7 +- 2 items, and duration is between 18-30s
What is long term memory?
The permanent memory store. 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, and the process of converting information between different stores is coding.
Baddeley’s research on coding (procedure)
He gave different lists of words to four groups of participants to remember:
Group 1 (acoustically similar): words sounded similar (eg. cat, rat)
Group 2 (acoustically dissimilar): words sounded different (eg. few, low)
Group 3 (semantically similar): words with similar meanings (eg. large, big)
Group 4 (semantically dissimilar): words with different meanings (eg. good, huge).
Baddeley’s research on coding (findings)
Participants were shown the original words and asked to recall them in the correct order.
When they did this task immediately, recalling from STM, they tended to do worse with acoustically similar words.
When they recalled the word list after 20 mins, recalling from LTM, they did worse with the semantically similar words.
These findings suggest that information is coded acoustically in STM and semantically in LTM
What is capacity?
The amount of information that can be held in a memory store
Who used a digit span test to measure capacity?
Jacobs
Digit span test procedure (Jacobs - capacity)
Jacobs investigated the STM capacity by measuring digit span.
The researcher reads out four digits and the participant recalls these out loud in the correct oder.
If this is correct the researcher reads out five digits and so on until the participant cannot recall the order correctly.
This indicated the individuals digit span.
Digit span test findings (Jacobs - capacity)
Jacobs found that the mean span for digits across all participants was 9.3 items.
The mean span for letters was 7.3.
Millers research on capacity
Miller made observations of everyday practice. For example, he noted that things come in sevens: 7 days of the week, 7 notes on the musical scale.
Miller thought that the span (ie. capacity) of STM is about 7 items, plus or minus 2. But he also notes that people can recall 5 words as easily as they can recall 5 letters. We do this by chunking - grouping sets of digits or letters into units or chunks.
What is duration?
The length of time information can be held in memory
Research on duration of STM (Peterson & Peterson)
Peterson and Peterson tested 24 undergraduate students. Each student took part in eight trials.
On each trial the student was given a consonant syllable (e.g. YGC) to remember. They were also shown a 3 digit number, the participants were asked to count backwards from this three digit number until told to stop. The counting backwards was to prevent rehearsal.
On each trial they were told to stop after a certain amount of time 3,6,9,12,15 or 18 seconds. Their findings found that STM has a duration of around 18 seconds, unless we repeat the information over and over (verbal rehearsal)
Research on duration of LTM (Bahrick)
Bahrick et al. studied 392 Americans aged betweeb 17-74.
Photo recognition test: 50 photos from high school yearbook
Free recall: names of graduating class
Photo recognition:
15 yrs after graduation: 90% accurate
48 yrs: 70% accurate
Free recall:
15 yrs: 60%
48 yrs: 30%
This shows that LTM may last up to a lifetime for some material.
