Psychology Memory 1

What is the duration of short-term memory?

18 seconds

What does memory fall within?

• Falls within cognitive psychology - a branch of psychology that involves the study of internal mental processes

• Includes perception, thinking, attention, language, learning & memory.

Define ‘capacity’

• The amount of information held in a memory store

Define ‘short-term memory’

• Stores the information we are currently aware of but only for a short amount of time.

• Capacity is between 5-9 items & coding is mainly acoustic.

Define duration

• The length of time information can be held in memory

Define long-term memory

• Permanent storage of information which is largely outside our awareness but can be recalled when needed, it has unlimited capacity

Describe research on capacity (George miller Princeton university 1956)

• Argued that most things come in 7s. E.g 7 notes on a musical scale, 7 days of the week etc.

• He concluded that on average, we can recall 7 items with a range of between 5-9 items in our short term memory

• Miller discovered we can easily increase the capacity of our short-term memory through ‘chunking’

Describe research on capacity - the digit span test developed by Jacobs (1887)

• Participant is given a set of digits & has to immediately recall them in order

• This is repeated increasing the amount of digits by 1 each time until the participant is unable to accurately recall them - this determines their digit span

• The mean digit span for participants was 9.3 for numbers. For letters it was slightly lower at 7.3 letters

Define coding

• The process of converting information to different firms

Describe Alan Baddeley (1966a,1966b) research on coding

• Gave lists of words to 4 participant groups to remember

1. Acoustically similar words = words sounding similar e.g cat, cab, cow

2. Acoustically dissimilar words = words not sounding similar e.g pit, few, cow

3. Semantically similar words = words with similar meaning e.g good, huge, hot

4. Semantically dissimilar words = words with different meanings e.g good, huge, hot

• When recalling from short-term memory, they tended to do worse with acoustically similar words

• When recalling from long-term memory, they did worse with semantically similar words

• These findings suggest info is coded acoustically in STM and info is coded semantically in LTM

Describe Margaret & Lloyd Peterson’s research on Duration of short term memory (1959)

• Tested 24 students in 8 trials

• Student given a consonant syllable e.g a 3 digit number

• Student counted backwards from this number until told to stop to prevent any mental rehearsal which would extend short-term memory duration

• Told to stop after e.g 3,6,9,12,15,18 seconds

• 3 seconds → 80%

• 18 seconds → 3%

• STM duration may be 18 seconds unless we do verbal rehearsal

Describe Bahrick’s research on duration of long term memory

• Barrack studies 392 American participants aged 17-74

1. Photo recognition test - consists of 50 photos, some from yearbooks

2. Free-recall test - test where participants recalled all names of graduating class

• 90% - Aged 17 → Photo recognition

• 60% - Aged 17 → Recall

• 70% - Aged 74 → Photo recognition

• 30% - Aged 74 → Recall

→ This shows that LTM may last up to a lifetime for some material.

Evaluate a strength of Baddeley

• Identified a clear difference between two memory stores

• The idea that STM uses acoustic coding & LTM is mostly semantic led to the multi-store model

Evaluate a limitation of Baddeley

• Used artificial stimuli rather than meaningful material

• Lack of information about coding in everyday tasks as more personal information may prompt participants to use semantic coding in STM tasks - limited application

Evaluate a strength of Jacobs’ research

• Can be replicated

• Jacobs’ findings have been confirmed by better controlled studies e.g Bopp & Verghaegan 2005, reinforcing validity

Evaluate a limitation of Millers’ research

• Overestimated STM capacity

• Cowan (2001) concluded the capacity is about 4 chunks, suggests that 5 items is more appropriate than 7 items

Evaluate a limitation of Petersons’ research

• Results may be due to interference & not decay of memory traces over time, limiting validity

Evaluate a strength of Rahrick’s research

• High external validity because researchers investigated meaningful memories which increased recall rates, reflected a realistic estimate of the duration of long term memory