Short Term Memory
Short term memory (STM)
Memory has been of interest since antiquity.
For centuries memory was seen just as a storage system, however experimental research in the last century has identified several functions for memory such as: * Encoding * Storage * Retrieval * Processing information.
Short term memory is also called * Primary memory (William James 1890) * Immediate memory * Working memory
Free recall task (Murdock 1962)
Participants had to remember lists of 10, 15, 20, 30 and 40 words. He also manipulated the presentation rate, the items were presented either every second or every 2 seconds. Participants recalled the words immediately after hearing it. Participants tend to recall the first and last items on the list better than the middle.
The better recall for the first items on the list is called the primacy effect, and for the last items this is called the recency effect.
These 2 effects suggest the presence of 2 different memory systems. One related to long term storage and the other related to short term storage.
Postman and Phillips (1965)
Also tested the hypothesis of two memory systems
Used a free recall paradigm with lists of 10, 20 and 30 words
Two main conditions: * No retention interval * Recall after a delay of 15 or 30 seconds, filled in with a counting task
The presence of a retention interval led to the elimination of the recency effect.
Waugh and Norman (1965)
Participants are shown a list of digits
They are then given a probe, which is one of the digits in the list
Their task is to retrieve the digit following the probe
List = (9 0 8 5 3)
Probe = 8
Answer = 5
Participants have to focus on one digit rather than the entire list
This technique essentially suppresses rehearsal
The results showed:
Weak memory for the last items presented so it can be concluded that suppressing rehearsal eliminates the recency effect
Waugh and Norman’s (1965)
Memory has been of interest since antiquity.
For centuries memory was seen just as a storage system, however experimental research in the last century has identified several functions for memory such as: * Encoding * Storage * Retrieval * Processing information.
Short term memory is also called * Primary memory (William James 1890) * Immediate memory * Working memory
Free recall task (Murdock 1962)
Participants had to remember lists of 10, 15, 20, 30 and 40 words. He also manipulated the presentation rate, the items were presented either every second or every 2 seconds. Participants recalled the words immediately after hearing it. Participants tend to recall the first and last items on the list better than the middle.
The better recall for the first items on the list is called the primacy effect, and for the last items this is called the recency effect.
These 2 effects suggest the presence of 2 different memory systems. One related to long term storage and the other related to short term storage.
Postman and Phillips (1965)
Also tested the hypothesis of two memory systems
Used a free recall paradigm with lists of 10, 20 and 30 words
Two main conditions: * No retention interval * Recall after a delay of 15 or 30 seconds, filled in with a counting task
The presence of a retention interval led to the elimination of the recency effect.
Waugh and Norman (1965)
Participants are shown a list of digits
They are then given a probe, which is one of the digits in the list
Their task is to retrieve the digit following the probe
List = (9 0 8 5 3)
Probe = 8
Answer = 5
Participants have to focus on one digit rather than the entire list
This technique essentially suppresses rehearsal
The results showed:
Weak memory for the last items presented so it can be concluded that suppressing rehearsal eliminates the recency effect
Waugh and Norman’s (1965)