Lecture 10 Psyco 350, A1 Fall, 2006

1
Lecture 10 Psyco 350, A1Fall, 2006

• N. R. Brown

2
Outline

• Misinformation Effect
• Memory Impairment
• Biased Guessing

3
Ebbinghaus(1885) The 1st Forgetting Function

• Main Findings
• AMOUNT of forgetting decreases w/ time
• Interpretation
• forgetting driven by decay information lost at a
  constant rate.

4
A Sample Decay Function

• Rate of forgetting constant over time
• Amount of forgotten/unit time ? with time

5
RI in the Real World

• General Idea New task-relevant information makes
  to difficult or impossible to recall or
  reconstruct prior beliefs, knowledge, responses
• A GOOD thing knowledge revision (Friedman
  Brown, 2000)
• And a BAD thing
• Hindsight Bias
• Misinformation Effect.

6
Misinformation Effect

• General Phenomenon
• memory for events distorted by exposure to
  inaccurate/misleading post-event information
• benign aspect post-event narration/discussion
  can alter autobiographical memories
• forensic issue post-event questioning can alter
  eyewitness testimony.

7
Misinformation Effect Basic Paradigm

• An event is witnessed (on tape)
• Post-event questioning used to introduce
  misinformation.
• Correct Post-event Information
• Did the repairman set down his hammer before
  taking the calculator?
• Misleading Post-event Information
• Did the repairman set down his screwdriver before
  taking the calculator?
•  Neutral
• Did the repairman set down his tool before taking
  the calculator?

8
Misinformation Effect Basic Paradigm

• Test Recognition for details of original event
• 2IFC two item forced choice
• Did you see a hammer or a screwdriver?
• Finding
• correct as a function of post-event info type
• correct gt neutral gtgt misleading

9
Loftus, Burns, Miller (1978)

• Materials
• 30 slides pedestrian being hit.
• traffic sign (STOP) appears in 1 slide.
• Questioning
• Did another car pass the red Datsun as it
  passed the STOP/YIELD sign?
• Delay 20 min
• Test 2IFC picture recognition
• picture w/ STOP vs picture w/ YIELD

10
Loftus, Burns, Miller (1978)

• Results
• Accurate post-event info 75 cor.
• Misleading post-event info 40 cor.
• Loftus Interpretation Memory change theory
  (knowledge revision)
• misleading information replaces the original,
  which is permanently lost

11
Misinformation Effect Other Interpretations

• Memory Coexistence (RI)
• Misleading information obscures original memory
  because it is more recent
• Support
• Memory better when original context is reinstated
• Memory better if people are warned of misleading
  information before test

12
Misinformation Effect Other Interpretations

• Source Monitoring Failure
• Errors reflect a failure to identify the source
• People remember information, but misremember
  where it came from
• Information that people are mislead about is
  often that which they make source errors for

13
Misinformation Effect Other Interpretations

• Biased Guessing Account
• McCloskey Zaragoza (1985)
• Central Notions
• Target and Foil (misinformation) can coexist
• Either or both can be forgotten
• Magnitude of misinformation effect depends on
• Prob (Target recalled)
• Prob (Foil recalled)
• (Foil selected over Target)

14
Biased Guessing Account

• Magnitude of misinformation effect depends on
• Prob (Target recalled)
• Prob (Foil recalled)
• (Foil selected over Target)
• Implication
• If foil removed from reco test, then
• MISLED CONTROL
• Reason
• remembered misleading inform no longer
  competing with original info.

15
Testing Biased Guessing Hypothesis

• Introduce modified recognition test.
• Predictions for recognition accuracy
• Biased Guessing Modified Misleading control
• Memory Change Modified Misleading lt control
• misleading info should ? memory for original info
  regardless of test

16
Rationale for Biased Guessing Prediction
Control Condition S ? no Y test S or Y
S, no Y
no S, no Y
Standard Test S ? Y test S or Y
S, no Y
S, Y
no S, Y
no S, no Y
Modified Test S ? Y test S or Z
S, no Z
no S, no Z
17
McCloskey Zaragoza (1985) Method

• Stims
• 79 slides of an office theft
• 4 s / slide
• 4 critical items coffee jar, magazine, pop can,
  tool
• Post-slide narrative
• 735-words long
• misinformation for 2 items neutral for 2 items

18
McCloskey Zaragoza (1985) Method

• Procedure
• view slides
• 10 minute filler
• read narrative
• 10 minute filler
• 36-item 2IFC recognition test
• The man slide the calculator beneath the ___ in
  his tool box
• standard test hammer vs screwdriver
• modified test hammer vs wrench

19
McCloskey Zaragoza (1985) Method

• Procedure
• view slides
• 10 minute filler
• read narrative
• 10 minute filler
• 36-item 2IFC recognition test
• The man slide the calculator beneath the ___ in
  his tool box
• standard test hammer vs screwdriver
• modified test hammer vs wrench

In Narrative
On Slide
Never encountered
20
McCloskey Zaragoza (1985) Results

• Standard Test
• replicates Misinformation effect Misled ltlt
  Control
• Modified Test
• consistent w/ Biased Guessing Misled ? Control
• access to original info unimpaired by post-event
  info.
• Consistent w/ Coexistence Source Monitoring
  Accounts