Memory: The capacity to retain
information over time.
• Encoding: the conversion of incoming
information into a form that can be stored in
memory.
• Storage: maintaining information in
memory over a period of time.
• Retrieval: the process of searching for
stored information and bringing it to mind.
Basic Reasons for Forgetting
• Encoding Failure: information did not get
into memory.
• Storage Failure: information has
disappeared from memory; it is no longer in
storage.
• Retrieval Failure: information is stored in
memory but it cannot be located.
Two Major Theories of
Forgetting
• Decay Theory: information in memory
eventually disappears if it is not used. (“Use
it or lose it.”)
• Interference Theory: information stays in
memory permanently even if it is not used.
Forgetting occurs because other things we
have learned somehow prevent us from
finding the information we want.
A famous experiment that supported the
interference theory and went against the
decay theory (Jenkins & Dallenbach, 1924).
You learn a list of 10 “nonsense syllables”
(like XUG or MUW), then get a test on it 1, 2,
4 or 8 hours later (“retention interval”).
Does it matter if you are asleep or awake
during this retention interval?
Predictions
We are exposed to new information when we are
awake but not when we are asleep.
Compare the amount recalled after 8 hours awake
to the amount recalled after 8 hours asleep.
Your choices:
(A) Recall will be higher after being asleep.
(B) Recall will be higher after being awake.
(C) Asleep = awake.
Decay Theory predicts: ?
Interference Theory predicts: ?
Predictions
Decay Theory predicts: C
Interference Theory predicts: A
10
5
Asleep
Awake
0
Syllables Recalled (out of 10)
Results Supported the
Interference Theory
0
2
4
Retention Interval
6
8