The effect of EMDR versus EMDR 2.0 on emotionality and vividness of aversive memories in a non-clinical sample

Abstract

Background: Eye movement desensitization and reprocessing (EMDR) therapy is a treatment meant to reduce vividness and emotionality of distressing memories. There is accumulating evidence that working memory taxation is the core of the working mechanism of EMDR therapy and that EMDR derives its effect by taxing the working memory (WM) with a dual task while actively keeping a disturbing memory in mind. From a theoretical stance, based upon assumptions derived from the WM theory, the effectiveness of EMDR therapy could be improved by several adaptations.
Objectives: To test the assumption that integrating these elements into the standard EMDR protocol would enhance EMDR therapy, this adapted version of EMDR (i.e. EMDR 2.0), was compared to standard EMDR in a laboratory setting. It was hypothesized that EMDR 2.0 would be more efficacious than standard EMDR, and show a greater decrease in emotionality and vividness than standard EMDR therapy. Our second hypothesis was that EMDR 2.0 would be more efficient than standard EMDR in that this variant needs less session time and a smaller number of sets (i.e. approximately 30 seconds of WM taxation).
Method: Non-clinical participants (N = 62, 79% female, mean age = 35.21) with a disturbing autobiographical memory were randomly allocated to receive either EMDR or EMDR 2.0. Emotionality and vividness of the memory were measured pre- and post-intervention, and at 1- and 4-week follow-up.
Results: The results showed no difference between EMDR and EMDR 2.0 in decreasing emotionality and vividness, and no difference in session time. However, participants in the EMDR 2.0 condition needed fewer sets than those in the standard EMDR condition.
Conclusion: The notion that EMDR 2.0 is more efficient is partially supported by the results showing participants needed less sets than in standard EMDR to reach the same results. Future research with clinical samples is warranted.

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European Journal of Psychotraumatology
ISSN: (Print) (Online) Journal homepage: https://www.tandfonline.com/loi/zept20
The effect of EMDR versus EMDR 2.0 on
emotionality and vividness of aversive memories
in a non-clinical sample
Suzy J.M.A. Matthijssen, Thomas Brouwers, Celeste van Roozendaal, Tessa
Vuister & Ad de Jongh
To cite this article: Suzy J.M.A. Matthijssen, Thomas Brouwers, Celeste van Roozendaal, Tessa
Vuister & Ad de Jongh (2021) The effect of EMDR versus EMDR 2.0 on emotionality and vividness
of aversive memories in a non-clinical sample, European Journal of Psychotraumatology, 12:1,
1956793, DOI: 10.1080/20008198.2021.1956793
To link to this article: https://doi.org/10.1080/20008198.2021.1956793
© 2021 The Author(s). Published by Informa
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CLINICAL RESEARCH ARTICLE
The eect of EMDR versus EMDR 2.0 on emotionality and vividness of aversive
memories in a non-clinical sample
Suzy J.M.A. Matthijssen
a,b
, Thomas Brouwers
a,b
, Celeste van Roozendaal
b
, Tessa Vuister
b
and Ad de Jongh
c,d,e,f
a
Altrecht Academic Anxiety Centre, Altrecht GGz, Utrecht, The Netherlands;
b
Department of Clinical Psychology, Utrecht University,
Utrecht, The Netherlands;
c
PSYTREC, Bilthoven, The Netherlands;
d
Academic Centre for Dentistry Amsterdam (ACTA), University of
Amsterdam and VU University Amsterdam, Amsterdam, The Netherlands;
e
School of Health Sciences, Salford University, Manchester, UK;
f
Institute of Health and Society, University of Worcester, Worcester, UK
ABSTRACT
Background: Eye movement desensitization and reprocessing (EMDR) therapy is a treatment
meant to reduce vividness and emotionality of distressing memories. There is accumulating
evidence that working memory taxation is the core of the working mechanism of EMDR
therapy and that EMDR derives its eect by taxing the working memory (WM) with a dual
task while actively keeping a disturbing memory in mind. From a theoretical stance, based
upon assumptions derived from the WM theory, the eectiveness of EMDR therapy could be
improved by several adaptations.
Objectives: To test the assumption that integrating these elements into the standard EMDR
protocol would enhance EMDR therapy, this adapted version of EMDR (i.e. EMDR 2.0), was
compared to standard EMDR in a laboratory setting. It was hypothesized that EMDR 2.0 would
be more ecacious than standard EMDR, and show a greater decrease in emotionality and
vividness than standard EMDR therapy. Our second hypothesis was that EMDR 2.0 would be
more ecient than standard EMDR in that this variant needs less session time and a smaller
number of sets (i.e. approximately 30 seconds of WM taxation).
Method: Non-clinical participants (N = 62, 79% female, mean age = 35.21) with a disturbing
autobiographical memory were randomly allocated to receive either EMDR or EMDR 2.0.
Emotionality and vividness of the memory were measured pre- and post-intervention, and at
1- and 4-week follow-up.
Results: The results showed no dierence between EMDR and EMDR 2.0 in decreasing
emotionality and vividness, and no dierence in session time. However, participants in the
EMDR 2.0 condition needed fewer sets than those in the standard EMDR condition.
Conclusion: The notion that EMDR 2.0 is more ecient is partially supported by the results
showing participants needed less sets than in standard EMDR to reach the same results. Future
research with clinical samples is warranted.
El efecto de EMDR versus EMDR 2.0 en la emocionalidad y la vivacidad de
las memorias aversivas en una muestra no clínica
Introducción: La terapia de desensibilización y reprocesamiento por movimientos oculares
(EMDR en su sigla en inglés) es un tratamiento pensado para reducir la vivacidad
y emocionalidad de las memorias angustiantes. Existe un cúmulo de evidencia que muestra
que la tasa de la memoria de trabajo es el centro del mecanismo de trabajo de la terapia EMDR
y que el EMDR deriva su efecto desde las tasas de memoria de trabajo (MT) con una tarea dual
mientras mantiene activamente una memoria perturbadora en mente. Desde una postura
teórica, basada en las asunciones derivadas de la teoría de la MT, la efectividad de la terapia
EMDR podría mejorarse por medio de varias adaptaciones.
Objetivos: Para probar la asunción que integrando estos elementos en el protocolo estándar
EMDR para potenciar la terapia EMDR, esta versión adaptada de EMDR (es decir, EMDR 2.0), fue
comparada con el EMDR estándar en un contexto de laboratorio. Fue hipotetizado que EMDR
2.0 sería más ecaz que el EMDR estándar, y mostraría una mayor disminución en la emocio-
nalidad y vivacidad de la terapia EMDR estándar. Nuestra segunda hipótesis fue que EMDR 2.0
sería más eciente que EMDR en que esta variante necesita menos tiempo de sesión, un
número menor de sets (es decir, aproximadamente 30 segundos de tasas de MT).
Método: Participantes no clínicos (N = 62, 79% mujeres, edad promedio = 35.21) con una
memoria autobiográca perturbadora fueron asignadas aleatoriamente a recibir ya sea EMDR
o EMDR 2.0. La emocionalidad y la vivacidad de la memoria fueron medidos antes y después de
la intervención, y seguimiento a 1 y a 4 semanas.
Resultados: Los resultados mostraron no diferencias entre EMDR y EMDR 2.0 en disminuir la
emocionalidad y la vivacidad, y no diferencia en el tiempo de la sesión. Sin embargo, los
ARTICLE HISTORY
Received 19 November 2020
Revised 8 June 2021
Accepted 27 June 2021
KEYWORDS
PTSD; EMDR; EMDR 2.0;
emotional memories
PALABRAS CLAVE
TEPT; EMDR; EMDR 2.0;
memorias emocionales
关键词
PTSD; EMDR; EMDR 2.0; 情绪
记忆
HIGHLIGHTS
• EMDR 2.0 requires fewer
desensitization sets than
EMDR to reach the same
effect, suggesting more
efficiency.
CONTACT Suzy J.M.A. Matthijssen s.matthijssen@altrecht.nl Altrecht Academic Anxiety Centre, Altrecht GGZ, Nieuwe Houtenseweg 12, Utrecht,
SH 3524
EUROPEAN JOURNAL OF PSYCHOTRAUMATOLOGY
2021, VOL. 12, 1956793
https://doi.org/10.1080/20008198.2021.1956793
© 2021 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.
This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial License (http://creativecommons.org/licenses/by-nc/4.0/), which
permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

participantes en la condición de EMDR 2.0 necesitaron menos sets que aquellos en la condición
EMDR estándar.
Conclusión: La noción de que EMDR 2.0 es más eciente es parcialmente apoyada por los
resultados mostrando que los participantes necesitaron menos sets que en EMDR estándar
para alcanzar los mismos resultados. Se justican investigaciones futuras con muestras clínicas.
非临床样本中EMDR 对比 EMDR 2.0对厌恶记忆的情绪性和生动性的影响
引言: 眼动脱敏和再加工(EMDR) 疗法是一种旨在减少痛苦记忆的生动性和情绪性的疗法° 越
来越多的证据表明, 工作记忆征税是 EMDR 疗法工作机制的核心, 并且 EMDR 通过在活跃记
住令人不安记忆的时候使用双重任务对工作记忆 (WM) 进行征税, 从而发挥其作用° 从理论
立场来看, 基于源自 WM 理论的假设, EMDR 治疗的有效性可以通过几种调整来提高°
目的: 为了检验将这些元素整合到标准 EMDR 方案中将增强 EMDR 治疗的假设, 在实验室环
境中对比了此改编版 EMDR（即 EMDR 2.0）与标准 EMDR ° 假设EMDR 2.0 将比标准 EMDR 更
有效, 并且比标准 EMDR 疗法可更大程度降低情绪性和生动性° 我们的第二个假设是 EMDR
2.0 比标准 EMDR 更有效, 因为此变体需要更少的疗程时间、更少的次数（即约 30 秒的 WM
征税）°
方法: 具有令人不安自传性记忆的非临床参与者（N = 62, 79% 女性, 平均年龄 = 35.21）被随
机分配接受 EMDR 或 EMDR 2.0° 在干预前、后以及在第 1 周和第 4 周的随访中, 测量记忆的
情绪性和生动性°
结果: 结果表明, EMDR 和 EMDR 2.0 在降低情绪性和生动性方面没有差异, 疗程时间也没有差
异° 但是, EMDR 2.0 条件下的参与者需要的次数少于标准 EMDR 条件下的参与者°
结论 : EMDR 2.0 更有效的观点由达到相同效果需要比标准 EMDR 更少次数的结果得到了部
分支持° 未来需要对临床样本进行研究°
Establishing the effectiveness of treating post-traumatic
stress disorder (PTSD) is one thing, enhancing treat-
ment by unravelling the underlying working mechan-
isms is another. Experimental research provides the
opportunity to study the mechanisms of action of ther-
apeutic procedures and, as a consequence, not only to
generate a better understanding of the therapy, but also
to acquire knowledge as to how to enhance its effective-
ness. For example, one of the first-choice treatments for
PTSD is eye movement desensitization and reproces-
sing (EMDR) therapy (De Jongh, Amann, Hofmann,
Farrell, & Lee, 2019; Matthijssen et al., 2020; Shapiro,
2018). This treatment procedure has proven to be both
effective and efficient (International Society for
Traumatic Stress Studies, 2018; Lewis, Roberts,
Andrew, Starling, & Bisson, 2020; Mavranezouli et al.,
2020; National Institute for Clinical Excellence, 2018).
However, both clinicians and researchers are
always striving for enhancing treatment because not
all patients respond equally well. An adapted version
of EMDR therapy has been developed specifically for
those individuals who do not respond. Possible
enhancements for the effectiveness or efficiency of
EMDR therapy are largely generated by experimental
research into the mechanisms and have focused on the
working memory theory (WMT) which presumes that
the effects of EMDR therapy can be attributed to
taxation of ones limited working memory (WM) capa-
city while recalling an aversive memory. The WMT
predicts that as a consequence of this dual tasking, the
aversive memory becomes less emotional and less
vivid (Gunter & Bodner, 2008; Van den Hout &
Engelhard, 2012), while based upon the work on
memory reconsolidation it could be assumed that the
memory reconsolidates as such in the long-term mem-
ory (e.g. De Quervain & Margraf, 2008).
Research into WMT and the degradation of aver-
sive memories shows there is potential into making
EMDR therapy more effective and efficient. Also clini-
cally, potential elements have been used in patient
samples already and showing large treatment effects
in an intensive treatment setting when combined with
sports, psycho-education and prolonged exposure
(e.g. Voorendonk, De Jongh, Roozendaal, & Van
Minnen, 2020). From both clinical observations in
the intensive treatments and experimental studies an
important finding is that providing more dual working
memory taxation seems more effective in reducing
emotionality and vividness than less dual taxation
(Littel & Van Schie, 2019; Maxfield, Melnyk, &
Hayman, 2008; Van Veen et al., 2015), which under-
lines the importance of increasing working memory
load. Another important finding from experimental
research is the support for the importance of keeping
the memory in mind while performing dual taxation
(Van Veen, Engelhard, & Van den Hout, 2016). This is
in line with WMT, which assumes that competition
between two tasks is essential; that is, participants
need to be engaged in both tasks (recalling a memory
and another WM taxing task) simultaneously. Further,
Cuperus, Laken, Van Schie, Engelhard, and Van den
Hout (2019) showed that combining short exposure to
a screenshot representing a negative memory and per-
forming a dual task resulted in larger decreases in
emotionality of the memory than just recalling the
memory while performing a dual task. These results
suggest improvements in EMDR therapy can be made
by maximizing working memory load and effectively
2S. J. M. A. MATTHIJSSEN ET AL.

activating the trauma memory while taxing and repro-
cessing it.
There are more suggestions to improve the effect of
EMDR therapy. This psychotherapy aims to reduce
PTSD symptoms by decreasing the emotionality of
intrusive memories that are mainly conceptualized as
being visual. Intrusions, however, appear in different
sensory modalities (Ehlers et al., 2002; Hackmann,
Ehlers, Speckens, & Clark, 2004). Matthijssen,
Verhoeven, van den Hout, and Heitland (2017) and
Matthijssen, Heitland, Verhoeven, and van den Hout
(2019) showed that auditory memories are mouldable.
Furthermore, there is some evidence that a larger
impact on working memory is found when both the
dual task performed and the (dominant) sensory mod-
ality of the memory are in the same modality
(Baddeley & Hitch, 1974; Matthijssen, Van Schie, &
Van den Hout, 2018). Hence, findings show anecdotal
evidence for another possible treatment enhancing
effect in that, albeit the general effect of WM taxation
is large, adding modality-specific taxation might
enhance the effectiveness of EMDR therapy somewhat
more.
Not only the WMT is of importance when consid-
ering mechanisms that could enhance the effectiveness
of EMDR therapy. Also other lines of research are
relevant in the search for optimizing treatment out-
come. To this end, one could theoretically argue the
possible clinical relevance of unexpected (surprise)
effects. There is evidence to suggest that the element
of surprise makes complex memories mouldable by
destabilizing them (Sinclair & Barense, 2018). In this
respect Visual Schema Displacement Therapy
(VSDT), a relative novel and promising therapeutic
procedure which uses an element of surprise has pro-
ven to be capable of reducing the emotionality and
vividness of aversive memories (Matthijssen,
Brouwers, van den Hout, Klugkist, & de Jongh, 2021;
Matthijssen, Van Beerschoten, De Jongh, Klugkist, &
Van den Hout, 2019).
Linked to this is another potentially interesting
mechanism and potential active therapeutic ingredient
that may be capable of enhancing trauma-focused
therapy, and that is the addition of arousal (Foa,
Riggs, & Gershuny, 1995; Jaycox, Foa, & Morral,
1998). There is evidence to suggest that arousal could
boost memory updating during reconsolidation (e.g.
Anderson, Yamaguchi, Grabski, & Lacka, 2006; Stein,
Rohde, & Henke, 2015; Van den Hout, Eidhof,
Verboom, Littel, & Engelhard, 2013, Littel et al.,
2017b). In the same vein, a placebo-controlled study
showed that reducing arousal by administering beta
blockers reduced the effects of eye movements on
vividness of emotional memories (Littel et al.,
2017a). Thus, it is conceivable that, besides the afore-
mentioned ingredients, increasing arousal might also
give a boosting effect to the efficacy of trauma-focused
therapies, such as EMDR therapy.
Based upon the work and the standard EMDR
protocol developed by Francine Shapiro (2018), and
inferred from the WMT and other research findings as
well as clinical observations, it could be assumed that
integrating the aforementioned elements into the stan-
dard EMDR protocol would enhance EMDR therapy,
making treatment potentially more effective and effi-
cient. Therefore, the purpose of the present study was
to compare the effects of using the standard EMDR
protocol with an adapted version of EMDR therapy,
a procedure referred to as ‘EMDR 2.0’, using a non-
clinical sample. The latter method is standard practice
when investigating a new treatment protocol within
a randomized controlled trial (Spieth et al., 2016). It
was hypothesized that EMDR 2.0 would be more effi-
cacious than standard EMDR, and show a greater
decrease in emotionality and vividness than standard
EMDR therapy.
A central element of EMDR therapy is that the
therapist performs ‘sets’ (approximately 30 seconds)
of dual WM taxation while the patient simultaneously
recalls the trauma memory. It is conceivable that by
taxing working memory more in EMDR 2.0 compared
to EMDR, this would result in a more efficient therapy
with less session time and fewer number of sets needed
as in standard EMDR. Therefore, our second hypoth-
esis was that EMDR 2.0 would be more efficient than
standard EMDR in that this variant needs less treat-
ment time, and a smaller number of sets.
1. Method
1.1. Participants
A total of 130 participants were recruited via posters at
the Utrecht University campus and through social
media posts. Thirty-four declined participation after
receiving additional study information, and 14 parti-
cipants could not be reached to schedule an appoint-
ment. After completing a screening questionnaire at
the start of the experiment, 13 persons were excluded
based on exclusion criteria. More specifically, four
persons rated the subjective unit of disturbance
(SUD) of their negative emotional memory below the
threshold, and nine persons had knowledge of EMDR
treatment or the current study goals. Thus, 69 partici-
pants took part in the present study. An additional
seven persons were excluded during or following the
experiment. Four persons were excluded because the
therapist deviated from treatment protocol, and three
were excluded because the SUD related to the selected
memory was rated lower then threshold upon starting
the experiment. Therefore, the final sample included
in the analyses consisted of 62 participants, with
EUROPEAN JOURNAL OF PSYCHOTRAUMATOLOGY 3

a mean age of 35.21 years (SD = 13.49) and 79.0%
being female.
An a priori power analysis and statistical proce-
dures were preregistered on OSF (https://osf.io/
zrvp9). We deviated from the preregistered statistical
method due to a preference for the use of Bayesian
statistics compared to Null Hypothesis Significance
Testing (NHST), though the same type of analyses
were run. Albeit Bayesian statistics are less dependent
on strict power analyses, the current N of >30 partici-
pants per group is considered sufficient to detect the
hypothesized differences using Bayesian statistics.
1.2. Procedure
Study procedures were approved by the Faculty Ethics
Review Board (FERB) of the Faculty of Social and
Behavioural Sciences, Utrecht University (UU;
Registration ID: 19–127). The experiment was con-
ducted by two graduate students of the Clinical
Psychology Master’s programme of Utrecht
University. Potential participants applied by emailing
the student researchers, upon which they were called
to elucidate study procedures, screen for exclusion
criteria and schedule an appointment. Afterwards,
they received an email containing appointment details
and the information letter. The letter informed them
about study procedures, informed consent, potential
risks and benefits of participation, reimbursement,
confidentiality and anonymity of data, and contact
information of all researchers involved. At the start
of the experiment, participants were taken to a lab
appointed for informed consent and screening proce-
dures. The student researchers checked whether all
procedures were fully understood. Participants then
signed an informed consent form. Next, they were
screened for the exclusion criteria using
a questionnaire. Exclusion criteria were that partici-
pants were not able to recall a disturbing memory of
a specific event with a minimum SUD rating of six on
a scale from zero to ten, insufficient command of the
Dutch language, current use of benzodiazepines, anti-
depressants, antipsychotics or mood stabilizers,
a current psychiatric diagnosis of bipolar disorder,
major depression, PTSD, psychosis or autism spec-
trum disorder, current treatment for psychiatric pro-
blems, prior EMDR treatment less than three years ago
and/or more than ten sessions, uncorrected visual or
auditory impairment, and lastly, the use of alcohol or
drugs 12 hours prior to participation. Upon inclusion,
they were escorted to a second lab where the EMDR
therapist was present for the treatment procedures.
Next, treatment procedures were explained and there-
after executed following protocolled procedures.
A student researcher (out of sight for the participant,
but visible for the therapist) was present during all
treatment sessions to evaluate protocol adherence
and was able to give a signal to the therapist with
flashcards if they were not adhering. They also
recorded study data. After finishing the treatment
procedure, the student researcher planned two follow-
up appointments by phone after one and four weeks.
Both appointments consisted of the collection of SUD
and vividness ratings of the selected aversive memory.
At the end of the second follow-up appointment,
participants were thanked, debriefed and reimbursed
by electronic payment or course credits.
1.3. Materials
1.3.1. Emotionality
The SUD-scale is used as an index of perceived inten-
sity of disturbance or distress induced by recalling
a negative emotional memory or image (Wolpe,
1969). The score is measured on a 11-point Likert
scale ranging from 0 (no distress at all) to 10 (max-
imum distress). The SUD-scale is integrated within the
standard EMDR protocol and is frequently used in
EMDR-related research (Shapiro, 2018) and shows
good psychometric properties to measure emotional-
ity of memories (Kim, Bae, & Park, 2008). In the
current study, SUD scores of the selected disturbing
memory were assessed verbally by the experimenter
during the screening, at the start and end of the
experiment, and via telephone at one and four-week
follow-up. Participants were excluded if the SUD score
was rated lower than six at the start of the experiment.
1.3.2. Vividness
Participants rated the vividness of the recalled disturb-
ing memory on a 11-point Likert scale ranging from 0
(not vivid at all) to 10 (very vivid). Vividness is
a measure often used in experimental EMDR research
(e.g. Van den Hout & Engelhard, 2012). In the current
study, vividness scores of the selected disturbing mem-
ory were assessed verbally by the experimenter at the
start and end of the experiment, and via telephone at
one and four-week follow-up.
1.3.3. Session time and number of sets
The researcher measured the duration of the session,
the total number of ‘sets’ (i.e. every set being approxi-
mately 30 seconds dual WM taxation during memory
recall) and sets per ‘round’ (i.e. all sets from back to
target to back to target moment).
1.4. Treatment
The treatment was carried out by eleven therapists
who attended an accredited course of EMDR therapy.
The therapists were also trained in ‘EMDR 2.0’ and
were supervised by the principal investigator, an
EMDR Europe consultant and last author, an EMDR
Europe accredited trainer in EMDR therapy. To
4S. J. M. A. MATTHIJSSEN ET AL.

ensure protocol adherence, fidelity checks were per-
formed by supervising video recordings of trial ses-
sions. Depending on the condition, the standard
Dutch EMDR protocol (Ten Broeke, De Jongh, &
Hornsveld, 2019), or EMDR 2.0 protocol (De Jongh
& Matthijssen, 2019) was used.
1.4.1. EMDR
EMDR uses a manualized standard EMDR, eight-
phase protocol (De Jongh & Ten Broeke, 2019;
Shapiro, 2018, for a description, see https://www.
emdria.org/about-emdr-therapy/experiencing-emdr-
therapy/). An essential part of the EMDR procedure
consists of the activation and reprocessing of the trau-
matic memory by asking the patient to bring up the
memory and to concentrate on the most disturbing
image of the memory, a self-referencing dysfunctional
belief, and its emotional and somatic components.
Next, the clinician instructs the patient to concentrate
on these elements of the memory while simulta-
neously performing another task, most commonly
following the hand of the therapist with their eyes. In
the present study, participants were asked to report
their upcoming associations after each set (± 30 sec) of
working memory taxation. These sets were repeated
until the participant reported similar associations two
subsequent times, thereby completing one desensitiza-
tion round, after which the therapist returned back to
target to evaluate treatment progress by evaluating the
disturbance and after that, to proceed with a new
series of sets (i.e. a new round). These desensitization
rounds were repeated until the maximum session time
of 20 minutes was reached or sooner when the SUD
rating decreased to zero. During the assessment and
prior to the positive closing (last phase of the session)
SUD and vividness of the selected memory were rated.
1.4.2. EMDR 2.0
The EMDR 2.0 treatment protocol is also based on the
standard EMDR eight-phase protocol (see above), but
is supplemented by text parts aimed at motivating the
participant to explicitly place the memory in his or her
working memory, thoroughly activating the disturbing
memory while a variety of specific WM taxation tech-
niques are added in the desensitization phase of the
procedure. More specifically, EMDR 2.0 covers three
core elements. Firstly, informing and motivating the
patient to place the traumatic memory in all its detail
in the working memory with the purpose to engage in
the treatment and to provide a rationale as to what the
core and working mechanism of the therapy is.
Secondly, helping the person to activate the memory
and to optimize the arousal of the memory network and
the body. The therapist increases activation of the target
memory by stimulating the person to focus on all
sensory aspects of the memory, and not only the visual
content (i.e. auditory, olfactory, gustatory and tactile
aspects). Thirdly, to reprocess the memory with the
use of a diversity of new memory-taxing tasks and
techniques covering different sensory modalities
(desensitization techniques; see Table 1). Therapists
are encouraged to expand and adapt these as is appro-
priate for the participant. In the desensitization phase
four aspects were taken into account.
1.4.2.1. Maximizing WM taxation. WM taxation is
maximized by combining different tasks. The partici-
pant starts with complicated tapping patterns and very
fast eye-movements. Subsequent sets combined fast
eye-movements with one or several of six different
tasks: 1. Varying eye-movement patterns instead of
horizontal (e.g. diagonal, circles), 2. Counting or spel-
ling tasks, 3. Repeating tongue twisting word combi-
nations like ‘tick-tock’ 4. Performing the V-step:
standing up and making diagonal steps, 5. Tapping
tasks, 6. Introducing (strong) distracting smells and
tastes.
1.4.2.2. Adding surprise effects. Surprising the parti-
cipant by making unrelated comments, asking unre-
lated questions (e.g. ‘What do you think of the
weather?’) or making unexpected movements.
1.4.2.3. Inducing arousal. The therapist induces
arousal by unexpectedly clapping the hands or loudly
saying words or making sudden sounds or very sud-
den gestures.
1.4.2.4. Modality specific taxation. The therapist
matches the WM taxation to the modality of the target
Table 1. Desensitization tasks and interruptions part of the EMDR 2.0 protocol.
Task/Interruption Modality
Superfast eye-movements, around 10 cm away from the nose Visual
Tapping a sequence on the legs Kinaesthetic
Diagonal, up/down, circle (or other shape) eye-movements Visual
Counting, spelling words, reciting alphabet, singing a song * Auditory
Repeating ‘tick, tock’ or ‘left, right’ * Auditory
Clapping, saying ‘whoosh’, other arousal inducing tasks Auditory/Visual
Surprise effect by therapist by strange remarks/questions/movements Auditory/Visual
V-step movement Kinaesthetic
Strong smells (perfume, tea, ammonia, etc.) Olfactory
Strong tastes (sweets, mints, lemon, etc.) Gustatory
Note. * = Therapist can provide additional interference by speaking simultaneously during performance of these tasks
EUROPEAN JOURNAL OF PSYCHOTRAUMATOLOGY 5

memory. For example, when the target memory has
a strong aversive auditory component (e.g. deep sigh-
ing), an auditory taxation method is used as an add-on
task (e.g. counting and spelling). Besides the visual,
auditory and kinaesthetic tasks described under
Maximizing WM taxation, several objects were avail-
able in the lab to induce modality-specific taxation
(e.g. gustatory: sweets).
1.5. Design
The study employed a two (Condition: EMDR and
EMDR 2.0) by four (Time: pre, post, follow-up 1,
follow-up 2) mixed design. Participants were ran-
domly assigned to one of the conditions by order of
inclusion. The within-subjects variable time consisted
of SUD and vividness assessments at the start of the
experiment (pre), after completion (post), at one-week
follow-up (follow-up 1) and at four-week follow-up
(follow-up 2). The between-subject variable was the
condition, being either EMDR or EMDR 2.0. For
efficiency, dependent variables were measurements of
total session time and number of sets performed. Sets
were measured both in total and as an average per
round.
1.6. Data analysis
All data were analysed using a Bayesian approach in
the statistical software JASP (v0.12.2; JASP Team,
2020). This method uses the Bayes factor (BF) to
evaluate relative support for one hypothesis or model
compared to one or multiple others. If BF > 1, there is
support for the tested model, with larger values indi-
cating more support. If BF < 1, there is support for the
null or alternative model(s), with smaller values indi-
cating more support. If BF values approximate one
there is equal support for the models. The strength
of Bayesian hypothesis testing compared to NHST lies
in the absence of stringent cut-off values (e.g. p < .05)
and resultant arbitrary dichotomous decisions.
However, indication on how to interpret BF values is
considered pragmatic. Generally, BF values of 1–3 are
considered anecdotal evidence for the tested hypoth-
esis, a BF of 3–10 is interpreted as moderate support,
and BFs >10 indicate strong support.
Overall group differences in efficacy were analysed
using Bayesian repeated measures analyses of variance
(ANOVAs) with condition (EMDR, EMDR 2.0) as
between-subjects variable and SUD and Vividness rat-
ings representing the within-subjects variable time (pre,
post, follow-up 1, follow-up 2). To interpret slope dif-
ferences between the relevant time points, subsequent
Bayesian Independent Samples T-Tests (ISTTs) were
conducted with condition as independent variable and
SUD and Vividness difference scores (pre-post, pre-
follow-up 1, pre-follow-up 2) as dependent variable.
Efficiency was analysed using Bayesian ISTTs with con-
dition as independent variable and total session time,
number of sets per round and number of sets as depen-
dent variables.
When reporting results, the notation BF
m
quantifies
the support, the data shows for one model when com-
pared to all other tested models. BF
m
is computed by
dividing the posterior odds of the specific model by the
average posterior odds of all other tested models. For the
ANOVAs, these models include main effects for
Condition and Time, the interaction effect, and
a combination of these effects. For the other tests in
general, the notation BF
10
is used to express the support
for a single hypothesis (e.g. ISTT: mean group scores are
different) versus the null hypothesis. BF
01
expresses sup-
port for the null hypothesis compared to the tested
hypothesis. Default priors were used for all analyses
(Rouder, Morey, Speckman, & Province, 2012). JASP
automatically corrects for multiple testing by fixing to
0.5 the prior probability that the null hypothesis holds
across all comparisons (Westfall, Johnson, & Utts, 1997).
2. Results
2.1. Descriptive statistics
Data of 62 participants were analysed. One follow-up
SUD measurement was removed from the analyses
because at the second follow-up it appeared the partici-
pant misinterpreted the question rating the current emo-
tionality in relation to the whole traumatic period,
instead of the emotionality induced by retrieving the
memory of the traumatic event. At the second follow-
up, one participant could not be reached resulting in
missing values for that participant for both SUD and
vividness.
The number of participants treated per therapist
ranged from four to eight. At baseline, participants
rated the emotionality of their selected target memory
with an average SUD of 8.01 (SD = 1.03). The mean
score of the vividness of the memory was 7.99
(SD = 1.25). Treatment in both conditions was con-
ducted for a maximum of 20 minutes, albeit 25 partici-
pants (40.32%) reported a SUD-rating of zero before the
session time was over. This resulted in a mean session
time of 16.92 minutes (SD = 4.54). Approximately four
desensitization rounds were performed on average (M
= 4.24, SD = 1.58). A round was concluded when
a participant did not report any new associations,
which happened at an average of 2.76 (SD = 1.42) sets.
2.2. Randomization check
The null model with no differences in SUD and vivid-
ness ratings between groups at baseline was supported
by Bayesian ISTTs (SUD: BF
01
= 3.58; Vividness: BF
01
= 3.85). The null models for randomization of age
6S. J. M. A. MATTHIJSSEN ET AL.

(Bayesian ISTT; BF
01
= 3.73) and gender (Bayesian
contingency table; BF
01
= 1.78) were supported as
well. A Bayesian univariate ANOVA comparing pre
to post SUD and vividness decreases between the
therapists showed support for the null model with no
differences between therapists (SUD: BF
m
= 2.93;
Vividness: BF
m
= 1.58). Also, no difference between
therapists for session time was found (BF
m
= 1.56).
2.3. Ecacy
2.3.1. Emotionality
The Bayesian repeated measures ANOVA with
Condition (EMDR, EMDR 2.0) as between subjects
variable and SUD ratings representing the within sub-
jects variable Time (pre, post, follow-up 1, follow-up
2) shows the most support for a model with only
a main effect of Time (BF
m
= 11.52). Post-hoc tests
show strong support for SUD decrease ratings from
pre to post (BF
10
= 1.34 × 10
22
; Cohen’s d = 2.27), pre
to follow-up 1 (BF
10
= 3.87 × 10
23
; Cohen’s d = 2.44),
and pre to follow-up 2 (BF
10
= 4.84 × 10
26
; Cohen’s
d = 2.90). SUD ratings did not decrease further follow-
ing the post test, meaning that support was found for
the model without mutual decreases between post,
follow-up 1 and follow-up 2 ratings (BFs
01
> 4.24).
The model with a main effect for Time and Condition
is not convincingly supported (BF
m
= 1.29). There is
strong evidence against the model including the inter-
action effect (BF
m
= 0.06). The planned post hoc
Bayesian ISTTs comparing decreases in SUD ratings
from pre to post, follow-up 1 and follow-up 2 show
support for the lack of differences between conditions
(pre-post: BF
01
= 3.83; pre-follow-up 1: BF
01
= 3.53;
pre-follow-up 2: BF
01
= 3.41). For a graphical overview
of all SUD ratings, see Figure 1.
2.3.2. Vividness
The Bayesian repeated measures ANOVA comparing
vividness scores over time between groups shows most
support for the model including only a main effect of
Time, BF
m
= 10.65. This main effect is further
Figure 1. Mean (SE) SUD scores for all time points specified per condition. EMDR = Eye Movement Desensitization and
Reprocessing; SUD = subjective unit of disturbance; FU1 = follow-up after 1 week; FU2 = follow-up after 4 weeks.
Figure 2. Mean (SE) vividness scores for all time points specified per condition. EMDR = Eye Movement Desensitization and
Reprocessing; FU1 = follow-up after 1 week; FU2 = follow-up after 4 weeks.
EUROPEAN JOURNAL OF PSYCHOTRAUMATOLOGY 7

specified by post-hoc tests yielding a strongly sup-
ported decrease in vividness ratings from pre to post
(BF
10
= 2.43 × 10
11
; Cohen’s d = 1.30), pre to follow-up
1 (BF
10
= 7.42 × 10
12
; Cohen’s d = 1.41), and pre to
follow-up 2 (BF
10
= 9.64 × 10
17
; Cohen’s d = 1.87).
Also, decreases from post to follow-up 2 (BF
10
= 35.45;
Cohen’s d = 0.46) and follow-up 1 to follow-up 2
(BF
10
= 58.74; Cohen’s d = 0.48) were supported by
post hoc tests. The null model with no decrease from
post to follow-up 1 was supported (BF
01
= 4.99). The
model including both the main effect of Time and
Condition was not convincingly supported, BF
m
= 1.23. The analysis shows evidence against the
model including the interaction effect, BF
m
= 0.16.
Separate ISTTs showed support for the models includ-
ing equal decreases in vividness ratings between con-
ditions and the specific time points (pre-post: BF
01
= 3.76; pre-follow-up 1: BF
01
= 2.11; pre-follow-up 2:
BF
01
= 3.37). For a graphical overviewof all vividness
ratings, see Figure 2.
2.4. Eciency
2.4.1. Session time
A Bayesian ISTT showed anecdotal support for the
null model with no differences in session time between
groups, BF
01
= 1.35. The standard EMDR sessions
lasted an average of 16.02 minutes (SD = 4.91), the
EMDR 2.0 sessions an average of 17.82 minutes
(SD = 4.01).
2.4.2. Number of sets
A Bayesian ISTT showed support for the model with
differences between groups for the number of sets,
BF
10
= 6.53. Participants in the EMDR 2.0 condition
conducted fewer sets within the session (M = 9.03;
SD = 4.36) than participants in the standard EMDR
condition (M = 12.90; SD = 6.30). Likewise, the num-
ber of average sets per round differed between groups
(BF
10
= 72.23). Participants in the EMDR 2.0 condi-
tion also needed fewer sets per round (M = 2.15;
SD = 0.95) and thus went back to target faster than
participants in the standard EMDR condition (M
= 3.38; SD = 1.55).
3. Discussion
The purpose of the present study was to compare the
efficacy and efficiency of the EMDR 2.0 therapy pro-
tocol with the standard EMDR protocol in affecting
emotionality and vividness of distressing autobiogra-
phical memories in a non-patient sample. The results
of the present study did not support the hypothesis
that EMDR 2.0 would be more effective than tradi-
tional EMDR therapy in reducing emotionality and
vividness of distressing memories, both directly post-
intervention and at follow-up after one and four
weeks. Individuals in both treatment conditions
showed equal effects. There was only partial support
for the hypothesis that EMDR 2.0 would be more
efficient than EMDR. Participants in the EMDR 2.0
condition needed fewer sets than in the EMDR con-
dition to induce the same emotionality and vividness
decreasing effect as EMDR. Conversely, the two inter-
ventions did not differ in session-duration-time.
If fewer sets were needed in EMDR 2.0 to get
similar effects, why were effects not observed in dif-
ference in session time or lower emotionality or vivid-
ness scores? One could argue that the enhanced WM
loading used in EMDR 2.0 could have resulted in
overloading the WM and thereby making it impossible
for some participants to keep the aversive memory in
mind. Recent research has repeatedly shown that WM
taxation in EMDR follows a dose–response relation-
ship (Littel & Van Schie, 2019; Maxfield et al., 2008;
Van Schie, Van Veen, Engelhard, Klugkist, & Van den
Hout, 2016; Van Veen et al., 2015), but participants
also need to hold the memory in mind for it to be
processed (Van Veen et al., 2016). To what extent
participants were able to keep the disturbing memory
in mind while executing the dual tasks was not mon-
itored. Reports from several participants in the EMDR
2.0 condition after completing the study – admitting
they were happy to engage in the dual tasks so they
didn’t have to think about the distress-evoking mem-
ory – add to the likelihood of this possibility. On the
other hand, had there been no WM capacity left, and
had participants not been able to keep the memory in
mind, no effect of EMDR 2.0 would have been
observed. Future research should monitor whether
participants are keeping the memory in mind while
performing the dual tasks, and dual tasks should be
adjusted to their capacities if they are unable to do so.
Another, quite logical explanation for the lack of
differences in time and effect is the time that is used
for other elements in the intervention. The active
desensitization in EMDR 2.0 therapy, if one takes
into account that the duration of a set is approxi-
mately 30 seconds, was more or less 4.5 minutes,
while in conventional EMDR this was 6.5 minutes.
This suggests that the bulk of the intervention time
is filled with other elements of the therapy. Going
back to target and explaining the dual tasks are
examples of that. Even more so, since participants
went back to target more quickly in EMDR 2.0, it is
clear the back to target procedure also takes up more
time. Another explanation for the absence of differ-
ence in session time and effect might be due to the
sample used and the memories resulting therefrom.
It seems plausible that in patients suffering from
PTSD, more time is spent to process the memory
and therefore its desensitization to SUD zero
requires more sets. It is likely that due to the sample
of non-clinical participants, the aversive memories
8S. J. M. A. MATTHIJSSEN ET AL.

are easier to mould. Furthermore, one could argue
that for easy to manipulate memories there might
be, by all means, less difference in the effects of
EMDR and EMDR 2.0 since there might be less
need for added motivation, activation and/or desen-
sitization. Data was collected amongst a non-patient
sample who were motivated to participate in this
study, in contrast to the avoidance of the distressing
memory that is typically observed in patients suffer-
ing from PTSD (American Psychiatric Association,
2013). EMDR 2.0 is developed specifically for indi-
viduals who do not respond to EMDR because of
avoidance to fully activate a memory – an effect
witnessed in clinical practice, and because regular
dosages of working memory taxation seem insuffi-
cient to elicit effect.
Although not resulting in difference in session time,
the finding that in EMDR 2.0 fewer sets are needed to
reach the same effect in desensitization and reduction
of vividness brings up the question on the usefulness
of monitoring associations or the need to inquire
about associations. Although positive effects on
EMDR effectiveness have been observed by allowing
the internal association process (Rogers & Silver,
2002), the added effect of associations has not been
studied empirically (Van den Hout & Engelhard,
2012), and it is debatable whether associations, or
verbalizing these is an effective and thus essential
ingredient of EMDR therapy.
This study has several limitations. The first is the
use of a fixed time-limit of maximum 20 minutes. This
rendered us unable to detect whether there were any
differences in session duration when one would pro-
ceed to resolve emotionality of all memories.
Comparing total amount of time would have resulted
in a more straight comparison in session durations.
Furthermore, in the sample 25 out of 62 participants
reached a SUD score of zero, which reflects on the
mean session time, but also indicates that some of the
easier to mould memories compile a large part in the
means, thereby maybe not reflecting the variance in
effort of desensitizing. Also, no process measure was
included to determine the velocity of the decline of
emotionality ratings during the session. Therefore, it
is difficult to have a more refined view on the slope of
emotionality or vividness decrease. In future research,
longer sessions could be used to obtain better under-
standing of the decline in emotionality scores during
the session, and process measures could be taken into
account. Furthermore, although the use of non-
clinical sample sheds light on defining mechanisms,
a limitation of the use of such a sample is the general-
izability of the findings. More research must be con-
ducted in patient groups to determine whether EMDR
2.0 can be a better-working alternative to standard
EMDR for a specific groups of patients or not.
In conclusion, since EMDR 2.0 is found to be as
effective as standard EMDR in desensitizing aversive
memories in non-clinical participants, but results sug-
gest it might be somewhat more efficient, it is worth-
while investigating the efficacy and efficiency in
a target group of patients suffering from a clinically
relevant trauma-related symptom level. Also, future
research needs to focus on further dismantling work-
ing mechanisms. Since EMDR 2.0 is composed of
several possible enhancing mechanisms, research
needs to answer the question what mechanisms are
in the end responsible for improving clinical treatment
results.
Acknowledgments
We want to thank the EMDR therapists who participated in
this study.
An ethical statement if one is necessary
Institutional Review Board Statement:
The study was conducted according to the guidelines of the
Declaration of Helsinki, and approved by the Ethics
Committee of the Faculty of Social and Behavioural
Sciences, Utrecht University (Registration ID: 19-127;
approval date: 21 October 2019).
Informed Consent Statement
Informed consent was obtained from all subjects involved in
the study.
Author statement
SM, TB and AdJ designed the research and methodology.
CvR and TV collected the data. SM and TB supervised data
collection. SM and AdJ trained the EMDR therapists and
supervised treatment fidelity. TB analysed the data. SM, TB
and AdJ wrote the original draft paper, SM, TB, CvR, TV,
and AdJ reviewed and edited. SM, TB, CvR, TV, and AdJ
approved the final manuscript.
Disclosure statement
Ad de Jongh receives income from published books on
EMDR therapy and for training postdoctoral professionals
in this method. Ad de Jongh and Suzy Matthijssen received
income from webinars on EMDR 2.0. We have no other
known conflict of interest to disclose.
Data availability statement
Data available on request due to privacy/ethical restrictions. The
data that support the findings of this study are available from the
corresponding author, SM, upon reasonable request. The data are
not publicly available due to their containing information that
could compromise the privacy of research participants.
Furthermore, participants were not asked to give consent to save
their data in a public data repository.
EUROPEAN JOURNAL OF PSYCHOTRAUMATOLOGY 9

Funding
This research was supported by a grant from the Dutch
EMDR association (in Dutch: ‘Vereniging EMDR
Nederland’)
ORCID
Suzy J.M.A. Matthijssen http://orcid.org/0000-0002-
5537-112X
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