Coding, Capacity and Duration of Memory

Baddeley (1966) Coding in STM and LTM

• Acoustically similar words or dissimilar
• Semantically similar words or dissimilar
• Immediate recall was worse with acoustically similar words, so STM is acoustic.
• Recall after 20 minutes was worse with semantically similar words, so LTM is semantic.
• A limitation of Baddeley's study is that it didn't use meaningful material. The words used in the study had no personal meaning to the participant. When processing more meaningful information, people may use semantic coding even for STM tasks. This means the results of this study have limited application. We should be cautious about generalising the findings to different kinds of memory task.

Jacobs (1887) Capacity of STM

• Digit span: Researcher reads four digits and increases until the participant cannot recall the order correctly.
• On average, participants could repeat back 9.3 numbers and 7.3 letters in the correct order immediately after they were presented. 
• A limitation of Jacobs' study is that it was conducted a long time ago. Early research in psychology often lacked adequate control of extraneous variables. For example, some participants may have been distracted while they were being tested so they didn't perform as well as they might. This would mean that the results may not be valid because there were confounding variables that were not controlled. However, these results have been confirmed in other research, supporting its…