Coding,Capacity+ Duration

A01-Coding (Baddeley (1966a, 1966b))

Studied four groups of participants:

• Acoustically similar words

• Acoustically dissimilar

• Semantically similar

• Semantically dissimilar

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

Findings:

• Recalling immediately after learning the words: participants did worse on acoustically similar words.

• Recalling after 30 minutes: participants did worse on semantically similar words.

A03-Identified a clear difference between two memory stores.(Coding)

• One strength of Baddeley's study is that it identified a clear difference between two memory stores.

• But the idea that STM uses mostly acoustic coding and LTM is mostly semantic has stood the test of time. This was an important step in our understanding of the memory system, which led to the multi-store model.

A01-Capacity (Jacobs (1887))

• Researcher presents participants with four digits, which they must recall in the correct order out loud.  They then repeat this task with increasing number of digits until the participant makes a mistake.

• Digit span = the number of items that an individual can recall correctly.Found that the average span was 9.3 for digits and the mean span for letters was 7.3. 

A03-Study Has High Validity (capacity)

• One strength of Jacobs' study is that it has been replicated. The study is a very old one and early research in psychology often lacked adequate controls.

• For example, some participants' digit spans might have been underestimated because they were distracted during testing (an extraneous variable). Despite this, Jacobs' findings have been confirmed by other, better controlled studies since (e.g. Bopp and Verhaeghen 2005). This suggests that Jacobs' study is a valid test of digit span in STM.

A01-Duration (Bahrick (1975))

Graduates from a high school aged 17-74. Recall tested using yearbook:

• Free recall – participants had to recall names of individuals in class.

• Photo-recognition test.

Length of time impacted success of recall:

• Photo recognition: 

  • 15 years – 90% accuracy.

  • 48 years – 70% accuracy.

• Free recall:

  • 15 years – 60% accuracy.

  • 48 years – 30% accuracy.

A01- high External validity (Duration)

• This is because the researchers investigated meaningful memories (i.e. of people's names and faces).

• When studies on LTM were conducted with meaningless pictures to be remembered, recall rates were lower (e.g. Shepard 1967). This suggests that Bahrick et al.'s findings reflect a more 'real' estimate of the duration of LTM.