Page 4: Memory Duration Research

This section explores Peterson and Peterson duration of STM through detailed experimental procedures.

Definition: Duration refers to how long information remains stored in memory

Example: Participants had to remember consonant syllables while counting backward from three-digit numbers

The page also introduces Bahrick's study on long-term memory duration.

Coding, Capacity and Duration in Memory

The Baddeley (1966 study) investigated how information is encoded in short-term memory (STM) and long-term memory (LTM). This research, along with studies on memory capacity and duration, provides crucial insights into human memory processes.

Baddeley's Experiment on Memory Coding

The Baddeley (1966 procedure) involved giving different word lists to four groups:

1. Acoustically similar words (e.g. cat, can, cab)
2. Acoustically dissimilar words (e.g. cat, few, pit)
3. Semantically similar words (e.g. great, large, big)
4. Semantically dissimilar words (e.g. small, big, medium)

Participants were asked to recall words immediately and after 20 minutes.

Baddeley (1966 findings) showed:

• Immediate recall was worse for acoustically similar words, suggesting STM uses acoustic encoding
• Delayed recall was worse for semantically similar words, indicating LTM uses semantic encoding

Highlight: The Baddeley experiment revealed that short-term memory relies on acoustic coding, while long-term memory utilizes semantic coding.

Vocabulary: Acoustic coding refers to remembering information based on how it sounds, while semantic coding involves storing information based on its meaning.

Evaluation of Baddeley's Study

A limitation of Baddeley's research was the use of artificial stimuli lacking personal meaning for participants. This may limit generalizability to real-world memory tasks, as people might use semantic coding even for STM when processing meaningful information.

Research on Memory Capacity

Memory capacity refers to how much information can be held at one time. While LTM is believed to have unlimited capacity, STM capacity has been extensively studied.

Digit Span Test (Jacobs, 1887)

Jacobs' procedure involved:

1. Presenting participants with increasing numbers of digits
2. Asking for immediate recall in the correct order
3. Continuing until participants failed to recall all digits correctly

Findings showed a mean digit span of 9.3 items and a letter span of 7.3 items, supporting the concept of "7+-2" as the capacity of short-term memory.

Definition: Digit span is the number of digits a person can recall in the correct order immediately after presentation.

Miller's Chunking Theory (1956)

George Miller observed that many everyday practices involve sets of 7 items (e.g., 7 days in a week, 7 deadly sins). This led to the theory that STM "chunks" information into groups of about 7 items.

Example: The "Magic number 7 psychology" concept suggests that people can typically remember 7 (plus or minus 2) chunks of information in their short-term memory.