Collaborative interviewing of eyewitnesses: a field study
| Date | 16 October 2024 |
| Pages | 210-226 |
| DOI | https://doi.org/10.1108/JCP-04-2024-0028 |
| Published date | 16 October 2024 |
| Author | Eva A.J. van Rosmalen,Annelies Vredeveldt |
Collaborative interviewing of
eyewitnesses: a field study
Eva A.J. van Rosmalen and Annelies Vredeveldt
Abstract
Purpose –When eyewitnesses talk to each other after witnessing a crime, they can contaminate each
other’s memory. However, laboratory research shows that collaborative interviewing can also result in
correction of mistakesand retrieval of more new information. The aim of this study is to examine whether
these laboratory findingswould generalise to real police interviews in The Netherlands. Because littleis
known about which interviewing techniques Dutch police detectives use, the secondary aim was to
examinehow Dutch detectives approach individualand collaborative eyewitnessinterviews.
Design/methodology/approach –In a field study, witnessesof serious incidents (e.g. police shooting)
were interviewed individually and then collaborativelyby real investigators, resulting in 15 interviews of
1–2 h each from fivewitness pairs (5,534 details in total).Transcripts were coded for detail type,forensic
relevance, verifiability, retrieval strategies and interviewing techniques. Results were described using
both quantitativedescriptive data and a qualitativeanalysis of interview excerpts.
Findings –On average, collaborative interviews resulted in 131 new details, over half of which were
considered highly relevant to the police investigation. Interview excerpts demonstrated how content-
focused retrieval strategies(acknowledgements, repetitions, restatements, elaborations) can elicit new
and highly relevant details. Interviewers mostly asked clarifying questionsand equal numbers of open,
closed and yes/no questions,but rarely allowed for uninterrupted free recall. Interviewersasked a higher
proportionof open questions during collaborativeinterviews than during individual interviews.
Research limitations/implications –Limitations included the small sample size and lack of a control
condition.
Originality/value –To the best of the authors’ knowledge, this paper is the first to investigate the
effectivenessand feasibility of the CollaborativeEyewitness Interviewin real-world settings.
Keywords Collaboration, Interviewing, Cross-cuing, Error pruning, Eyewitness memory,
Retrieval strategy
Paper type Research paper
Investigative interviewing is a non-coercive approach used to gather information from
witnesses, victims or suspects, involving techniques such as open-ended questioning
and rapport-building to ensurethe accuracy and reliability of testimony (Milne and Bull,
1999). Investigative interviewers are generally advised to prevent eyewitnesses from talking
to each other, because this can lead to them incorporating each other’s mistakes or
reporting information heard from a co-witness as their own memories. The seminal studies
on social contagion (Meade and Roediger, 2002;Meade et al., 2023) and memory
conformity (Gabbert et al.,2006;Gabbert and Wheeler, 2017) have been invaluable in
highlighting the potential risks of co-witness discussion. Yet, the design of these studies did
not allow for potential benefits of co-witness discussion to emerge, even though such
benefits might be expected basedon Wegner’s transactive memory theory.
Wegner’s (1987,1995) theoryon transactive memory explains how group memory works by
dividing the responsibility of remembering information among its members. In a group,
each person remembers different pieces of information, creating a shared memory system.
This means that instead of everyone trying to remember everything, each person focuses
Eva A. J. van Rosmalen and
Annelies Vredeveldt are
both based at the
Department of Criminology,
Faculty of Law,
Vrije Universiteit
Amsterdam, Amsterdam,
The Netherlands.
Received 8 April 2024
Revised 25 June 2024
Accepted 5 July 2024
©Eva A.J. van Rosmalen and
Annelies Vredeveldt. Published
by Emerald Publishing Limited.
This article is published under the
Creative Commons Attribution
(CC BY 4.0) licence. Anyone may
reproduce, distribute, translate
and create derivative works of this
article (for both commercial and
non-commercial purposes),
subject to full attribution to the
original publication and authors.
The full terms of this licence may
be seen at http://creativecom-
mons.org/licences/by/4.0/legal-
code
The authors thank all witnesses
and interviewers willing to
participate in their study. The
authors appreciate the help from
the Rijksrecherche and Dienst
Regionale Recherche. The
authors are particularly thankful
to Rob Aartsen, who helped us
collect our data and commented
on our manuscript, as well as
Hille de Graaf and Jacqueline
Poot, who helped us collect our
data and gave us advice on the
data coding scheme. The
authorsare gratefulto Nine van
Eerde, who double-coded all
transcripts. Thiswork was
supported by the Society in
Science –Branco Weiss
Fellowship awarded to Annelies
Vredeveldt.
PAGE 210 jJOURNAL OF CRIMINAL PSYCHOLOGY jVOL. 15 NO. 2 2025, pp. 210-226, Emerald Publishing Limited, ISSN 2009-3829 DOI 10.1108/JCP-04-2024-0028
on certain details and relies on others for the rest. This collective system makes the group
more effective at storing, retrieving and using information than if each person worked alone.
Transactive memory operates based on two key conditions: firstly, members of the group
possess unique pieces of information that others lack (differentiation). Secondly, a shared
pool of knowledge exists among group members (integration). For example, aware of his
sister’s expertise in making movies, a brother prompts his sister to provide technical details
while he describes the plot, enriching their collective memory of the film. In legal contexts,
this theory suggests that eyewitnesses to an event might each recall different aspects of
what occurred, forming a more complete picture when talking about their memories, thus
highlighting the potential benefitsof collaborative recall in investigative procedures.
To measure not only the potential risks but also the potential benefits of co-witness
discussion, Vredeveldt and colleagues conducted a series of experiments on collaborative
recall by eyewitnesses (Vredeveldt et al.,2016,2017b,2018;Vredeveldt and Van Koppen,
2018;Vredeveldt et al., 2019). Specifically, they introduced the Collaborative Eyewitness
Interview, which involves initially interviewing witnesses individually and then allowing them
to discuss the event together during a second interview. This way, detectives and legal
professionals can check the original source of a statement as opposed to informal and
unmonitored discussion between witnesses. Vredeveldt et al. hypothesised that
collaboration with a co-witness might help witnesses remove errors from their testimony
(error pruning) and remember more information about the witnessed incident (cross-cuing).
They found mixed support for their hypotheses.
Regarding error pruning, there was a clear benefit of collaboration across studies:
eyewitnesses who are interviewed together are more accurate. Research shows that
collaborative eyewitnesses make fewer mistakes compared to nominal pairs (i.e. two
individuals who were interviewed separately; Vredeveldt et al.,2016,2017b;Vredeveldtand
Van Koppen, 2018;Vredeveldt et al.,2019;Rossi-Arnaud et al.,2020). This difference was
observed regardless of the level of acquaintance between pair members (Vredeveldt et al.,
2019). This error pruning effect may result from pair members directly correcting each
other’s mistakes but also from members censoring themselves during discussion. Error
pruning has also been observed in basic memory studies using simple (e.g. words; Harris
et al., 2012;Harris et al.,2013;Weigold et al., 2014;Nie and Guo, 2023) and complex
stimuli (e.g. film clip of an accident; Ross et al.,2004;Ross et al.,2008;Wessel et al.,2015).
Collaborative pairs also seem more resistantto suggestion, for example, by being less likely
to give in to leading questions (Rossi-Arnaud et al.,2019;Rossi-Arnaud et al., 2020;Rossi-
Arnaud et al.,2021
;Rossi-Arnaud et al.,2023). More specifically, members of collaborative
groups had similar tendencies to give in to leading questions but were more likely to be
corrected by their collaboratorsduring discussion (Rossi-Arnaud et al.,2021).
Cross-cuing occurs when one person’s statement cues another person’s memory, making
the latter recall new information that they would not have remembered independently. For
example, Witness A mentioning a bicycle may prompt witness B to mention the colour of
that bicycle. In Vredeveldt et al.’s studies (Vredeveldt et al.,2016,2017b,2018;Vredeveldt
and Van Koppen, 2018;Vredeveldt et al.,2019), there was no evidence that eyewitnesses
helped each other remember more information during the collaborative interview. However,
Vredeveldt et al. (2017b,2019) did find evidence for a delayed cross-cuing effect:
compared to nominal pairs, pairs that previously collaborated recalled more new correct
information during a third individual interview. This cross-cuing effect may not emerge
during collaboration because collaborative pairs can trigger but also disrupt each other’s
retrieval processes (Basden et al., 1997). So, collaborative pairs may add new information
but also leave out or forget to mention certain details. This disruption is typically found in
research using simple stimuli (e.g. words), showing that collaboration can lead to less
reported information (i.e. collaborative inhibition; Basden et al.,1997;Weldon and Bellinger,
1997;Barber et al.,2015). However, studies on witness interviews have shown that
VOL. 15 NO. 2 2025 jJOURNAL OF CRIMINAL PSYCHOLOGY jPAGE 211
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