Coding, Capacity and Duration of Memory

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  • Created by: hlouiset
  • Created on: 07-05-16 15:09

Short Term Memory: Coding

Acoustic

BADDELEY (1966)

Participants were asked to remember a list of 10 words that were shown on a screen for 3 seconds each. There was three conditions: Acoustically similar, semantically similar and a control group. In the acoustically similar condition the words sounded the same. In the semantically similar condition words had similar meanings. In the control group the words had no connection.

It was found that immediate recall was worse with acoustically similar words.

CONRAD (1964)

Participants were shown a presentation of sequences of 6 consonants and asked to recall the sequences.

It was found that letters that were similar sounding were more difficult to recall than letters thart sounded different. 

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Short Term Memory: Capacity

7+/- 2 bits of information

JACOBS (1887)

Digit Span

The researcher and participant were in a room together. The researcher read out four digits and increases every other digit span until the participant cannot recall the order of both spans of the same length correctly.

On average participants could repeat back 9.3 numbers and 7.3 letters in the correct order directly after they were presented.

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Short Term Memory: Duration

18-30 seconds maximum

PETERSON AND PETERSON (1959)

Trigrams

24 students were given a a set of three consonants to remember and a 3-digit number number to count backwards from for intervals of 3, 6, 9, 12, 15 or 18 seconds.

It was found that students recalled about 80% of the syllables correctly at 3 seconds and about 3% at 18 seconds.

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Long Term Memory: Coding

Semantic

BADDELEY (1966)

Participants were asked to remember a list of 10 words that were shown on a screen for 3 seconds each. There was three conditions: Acoustically similar, semantically similar and a control group. In the acoustically similar condition the words sounded the same. In the semantically similar condition words had similar meanings. In the control group the words had no connection.

It was found that after a 20 minute delay recall was worse with semantically similar words.

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Long Term Memory: Capacity

Unlimited

NOT POSSIBLE TO TEST

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Long Term Memory: Duration

Upto a lifetime

BAHRICK (1975)

Yearbook

392 Americans aged between 17 and 74 were asked to do a recognition test and a free recall test. The recognition test involved identifiying old high school classmates from 50 photos taken from the participants yearbook. The free recall test involved the participants listing the names of pupils in their graduating class.

It was found that participants that were tested 48 years after graduation were about 70% accurate in photo recognition and free recall was less accurate.

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Eval. Strengths

BAHRICK

The study used real life meaningful memories - When lab studies were done with meaningless pictures to be remembered the recall rates were lower - High external validity

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Eval. Limitations

BADDELEY

Didn't use meaningful material - The words used in the study had no personal meaning to the participants. When processing meaningful information people may use semantic coding even for short term memory tasks. This means the findings of Baddeley's study have limited application - Lacks external validity

JACOBS

Conducted early on - Early research often lacked adequate control of extraneous variables. For example, some participants may have been distracted while they are being tested so they did not perform as well as they might - Lacks validity

PETERSON AND PETERSON

An artificial stimulus was used - Trying to memorise trigram does not reflect most real life memory activities where what people try to remember is meaningful - Lacks external validity

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