Fiona Gabbert, Amina Memon

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Manipulating witnesses confidence in memory
Implications for memory conformity

• Fiona Gabbert, Amina Memon
• Daniel B. Wright

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Previous research

• Archival data shows crimes often have more than
  one witness (Valentine et al., 2003 Wright
  McDaid, 1996)
• Where multiple witness are present, co-witness
  discussion is common (Paterson Kemp, in press)

Challenge for researchers to maximise
ecological validity under controlled conditions
Typical finding peoples memory reports become
similar to one anothers following a
discussion (Gabbert et al. 2003, 2004 Mori et
al., 2003, 2004 Wright et al. 2000)
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Current research

• Does perceived memory quality influence
  susceptibility to memory conformity?

Experimental manipulation Perceived encoding
duration between dyad members is manipulated
whilst actual encoding duration is held constant
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Method
Design Between subjects design with 2 conditions
(perceived encoding time ½ vs.
x2) Participants 88 (Mean age 20 years)
tested in dyads Encoding material 4
pictures of different scenes
2 versions of each picture, each
with 2 contrasting critical items - So,
8 critical items in total
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Procedure
DV the amount of misinformation errantly
reported at test
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Coding

• All co-witness discussions were transcribed
• The transcriptions were coded to record which
  critical items were mentioned by each dyad member
• The free recall scripts were coded for the number
  of 1) correct/errant neutral details from the
  pictures 2) correct/errant critical items

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Results

• Question 1
• Is there a difference in memory performance
  between conditions (half vs. twice perceived
  encoding duration) ?

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Memory ability for neutral items
Number of accurate neutral items recalled (SD in
parentheses)
No main effects
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Results

• Question 2
• Is there a relationship between perceived memory
  quality and memory conformity?

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Effects of perceived memory quality
Average number of critical items reported in
each condition


plt0.05
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Results

• Question 3
• Is there a relationship between objective memory
  performance and memory conformity?

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Actual memory ability memory conformity

• Susceptibility to co-witness influence was not
  related to memory for the pictures
• Influenced 61.5 (SD 18.1) accurate items
• Not influenced 66.1 (SD 19.5) accurate items
• Correlation between number of accurate items of
  neutral information reported and number of errant
  co-witness details reported r .04, ns.

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Discussion

• Why does perceived memory quality mediate memory
  conformity?
• It is possible that the feedback influences
  confidence in ones memory (e.g., Wells
  Bradfield, 1998)
• This could affect metacognitive judgements about
  memory validity (e.g., Koriat Levy-Sadot, 1999
  2000)

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• Email me at f.gabbert_at_abdn.ac.uk
• For a copy of the accompanying paper
• For a copy of the stimuli used
• With any qs or comments about co-witness
  research
• thanks

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Source judgements attributed to errant critical
items reported at test