Decay theory of forgetting

1
Decay theory of forgetting

• Basic idea

Recall information
Learn information
TIME
Only the time in between learning and recall
affects how much information we can recall
2
TIME
Learn information
Recall information
Good recall
Recall information
T I M E
Learn information
Poor recall
As time increases, recall decreases
3

• Problem how do we set up an experimental
  situation where time is the ONLY event that
  occurs in between learning and recall.
• Practically speaking this is not possible to do!
• Decay theory was investigated by Brown and
  Peterson Peterson (1959).
• Task- Do the practical activity on page 276 in
• groups of 3.
• Write a brief summary of what you did and
• what you found

4

• The findings from studies such as this show that
  information in STM decays rapidly if rehearsal is
  prevented.
• Task- Copy the graph from page 277
• Performance drops by over 50 in 6 seconds!
• But, was time the only factor?
• Task- What did Waugh Norman do?
• What did they find?
• Try this out on a friend what do you find?
• What did Shallice find in addition to the
• findings of Waugh Norman (box K,
  handout)

5

• Evaluation decay cannot be the only factor in
  forgetting. The findings of Shallice indicate
  displacement too.
• Also, distractor tasks may have produced
  interference which could account for the
  findings.
• Cant really test the theory.
• Decay may be a factor in STM but we can recall
  info from many years ago, (remember Bahrick et al
  1975?) so not main factor in LTM.
• Decay is probably main factor in forgetting from
  Sensory Memory (see Sperlings work)

6
Displacement theory of forgetting

• STM limited capacity store so new information
  pushes out the old information leading to
  forgetting through displacement.

Old info needs to go to make room for new
New info
bit of info
bit of info
bit of info
bit of info
bit of info
bit of info
bit of info
STM full
7

• Evidence primacy recency effect.
• Task- How does displacement theory explain the
  primacy recent effect seen in the typical serial
  position curve?
• Why does delaying recall (Postman Philips)
  affect recall according to displacement theory?
• Evaluation the effects of displacement and
  decay cannot be separated. In practical terms the
  time interval between learning and recall will
  always be affected by both factors.

8
Interference theory of Forgetting

• Forgetting increases over time because of
  interference from similar, competing memories.
• Two types of interference-
• Proactive and Retroactive.
• Proactive interference
• old information affects the learning of new
  information.
• Interference works forward- A B
• In the lab learn list A then list B
• interference from A affects
  recall of B

9

• Retroactive interference
• New information affects the recall of previously
  learnt information.
• Interference works backwards A B
• In the lab learn list A then list B
• Interference from B affects recall of A
• Similarity of information affects interference,
• e.g. French Spanish both Latin root more
  interference
• French German different language root so
  less interference.

10

• Interference theory in usually investigated using
  paired associate lists.
• E.g. List A List B
• chair elephant chair daffodil
• hat - dog hat - carpet
• tree - gate tree - light
• Note first word of each pair is same for both
  lists partner is different.
• For PI, participants learn A, learn B and then
  try to recall B
• For RI, participants learn A, learn B and then
  try to recall A

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• Criticisms-
• Hardly a realistic learning task!
• Info is meaningless and is deliberately designed
  to interfere.
• Studies are carried out in a lab under controlled
  conditions.
• Lack ecological validity (what does this mean?)

12

• Task- Read pg 278 279. Summarise the three
  studies Jenkins Dallenbach Baddeley Hitch
  and Schmidt et al in diagrams e.g.
• Name
• Aim
• Condition 1 Condition 2
• Results Results
• Conclusion
• Evaluation

Why was the study being carried out?
What was being compared?
What was found?
What do the results mean?
Any good /bad points about the study?
13

• Evaluation of Interference theory of forgetting.
• (See also pg 280 of textbook and pg 2 3 of
  handout)
• PI and RI both reliably demonstrated in lab
  using paired associative learning.
• Naturalistic studies do suggest role of RI in
  forgetting.
• Lab studies lack ecological validity?
• Doesnt tell us about processes involved in
  forgetting
• Cant tell how much forgetting is due to
  interference
• Some disagreement over whether interference
  causes forgetting due to lack of accessibility or
  availability

14

• Forgetting practical exercise.
• You have 3 minutes to learn all 48 words on the
  sheet you have been given. You only need to learn
  the words in each category, not the category
  names.
• Now try to recall as many as you can in any order
  you have as much time as you like to do this.
  Use the sheet of paper you have been given to
  write the words on that you recall.

15

• Results table comparing number of words recalled
  by participants with and without cues.
• Participant Type of recall
• number Cued Uncued cued

16
Retrieval Failure

• Outline the basic idea behind this theory of
  forgetting.
• Summarise the study carried out by Tulving and
  Pearlstone in diagrammatic form. How do their
  results compare to ours?
• Use the following few questions to help you
  structure some notes on the encoding specificity
  principle. You will need to read page 280 /1 in
  your text book first.
• Encoding Specificity Principle.
• How do Tulving and Thompson propose we retrieve
  information from memory?
• What is the encoding specificity principle?
• What is the problem with the E.S.P.?
• Are cues important in retrieving information?

17

• Devise an experiment which would help you to test
  retrieval failure, in particular the
  tip-of-the-tongue phenomenon.
• Try this out on friends and family.
• What do you find?

18
Summary of studies on Retrieval Failure from
handout. Complete the diagram below on a sheet of
A4 paper
External context /environment. (summarise Box N)
Physical state. (Summarise Box O)
Retrieval Failure. (explain what this is)
Internal context /state psychological factors.
(Summarise Box P)