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Decay theory of forgetting

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Only the time in between learning and recall affects how much ... three studies; Jenkins & Dallenbach: Baddeley & Hitch and Schmidt et al in diagrams e.g. ... – PowerPoint PPT presentation

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Title: 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

11
  • 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)
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