Research on Coding in Memory Psychology
Baddeley's 1966 coding study examined how information is encoded in short-term and long-term memory. Participants were given different types of words to recall:
- Acoustically similar (sound alike)
- Acoustically dissimilar (sound different)
- Semantically similar (similar meanings)
- Semantically dissimilar (different meanings)
The results showed that for immediate recall (STM), participants performed worse with acoustically similar words. For delayed recall after 20 minutes (LTM), they performed worse with semantically similar words. This suggests that short-term memory coding is primarily acoustic, while long-term memory coding is primarily semantic.
Highlight: The study provides evidence that STM and LTM use different coding processes.
Vocabulary: Coding refers to the process of converting information from one memory store to another.
However, this study has limitations:
Example: The use of artificial word lists may not generalize well to real-world memory tasks.
Capacity and Duration of Short-Term and Long-Term Memory
Research on STM capacity includes:
- Jacobs (1987) digit span test: Found mean spans of 9.3 for digits and 7.3 for letters
- Miller's (1956) "magical number seven": Proposed STM capacity of 7 +/- 2 items
- Cowan's (2001) revised estimate: Suggests true STM capacity may be closer to 4 items
Definition: Chunking is the process of grouping individual pieces of information into larger, meaningful units to increase memory capacity.
Studies on memory duration include:
- Peterson & Peterson (1959): Demonstrated rapid forgetting in STM without rehearsal
- Bahrick (1975): Showed impressive long-term retention of high school memories decades later
Quote: "Photo recognition: 15 years after graduation - 90% accurate, 48 years -70%"
These studies highlight the stark differences between short-term memory duration (seconds without rehearsal) and long-term memory duration (potentially lifelong).
