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Frontiers in Psychology 01 frontiersin.org
The positive impact of
mindfulness interventions on the
explicit and implicit aective
attitudes toward vegetarian foods
AnnicaWinkelmair * and PetraJansen
Faculty of Human Sciences, University of Regensburg, Regensburg, Germany
Objectives: The main goal of our intervention study was to investigate whether
two conceptually dierent mindfulness interventions positively impacted the
explicit and implicit aective evaluations of vegetarian foods. We included
possible mediating variables (e.g., wellbeing) and related our results to the stage
model of self-regulated behavioral change (SSBC).
Methods: We implemented a compassion and caring-based mental training
(N = 31) and an adapted MBSR course (N = 34) as mindfulness interventions, and
a stress-reduction course (N = 26) as the active control group. The curriculums
consisted of 12 weekly group sessions á 75 min. All participants were tested pre-
and post-intervention and 3 months after the last intervention session, answered
questionnaires (mindfulness, compassion, wellbeing, items of the SSBC) and
completed an explicit aective evaluation task and an aective priming task.
Results: There was an improvement in the explicit attitudes toward vegetarian
foods regardless of the intervention group. In the SSBC, wefound a link between
the explicit attitudes toward vegetarian foods and the indicated stage in the model.
Multiple regression analysis revealed social and personal norms and a vegetarian/
vegan diet as the only significant predictors for goal intention in the SSBC.
Conclusion: The results of our study suggest that both conceptually dierent
mindfulness interventions, as well as a stress-reduction program, have a positive
impact on explicit aective attitudes toward vegetarian foods. Wehighlight the
meaning of inner dimensions and transformation for change processes for a
more sustainable diet and the role of social and personal norms.
KEYWORDS
mindfulness, attitudes, priming paradigm, vegetarian food, sustainable food
consumption, sustainability, behavioral change, intervention study
1. Introduction
e Intergovernmental Panel on Climate Change (IPCC) report states that “it is unequivocal
that human inuence has warmed the atmosphere, ocean, and land” (Allan etal., 2021, p.4). A
change of human behavior in a more sustainable direction thus seems inevitable. ere is also
an understanding that regarding sustainability, weneed to focus more on the inner worlds, like
emotions, thoughts, and beliefs, instead of addressing the climate crisis solely on collective or
technological levels (Ives etal., 2020). Current research highlights the importance of the inner
transformation that relates, for example, to values as a dimension of sustainability
OPEN ACCESS
EDITED BY
Nicholas T. Bello,
Rutgers, The State University of New Jersey,
UnitedStates
REVIEWED BY
Nadine Richter,
Dortmund University of Applied Sciences and
Arts, Germany
Suraj Benarji Teegala,
Rutgers University, UnitedStates
*CORRESPONDENCE
Annica Winkelmair
Annica.Winkelmair@ur.de
RECEIVED 05 April 2023
ACCEPTED 04 August 2023
PUBLISHED 04 October 2023
CITATION
Winkelmair A and Jansen P (2023) The positive
impact of mindfulness interventions on the
explicit and implicit aective attitudes toward
vegetarian foods.
Front. Psychol. 14:1158410.
doi: 10.3389/fpsyg.2023.1158410
COPYRIGHT
© 2023 Winkelmair and Jansen. This is an
open-access article distributed under the terms
of the Creative Commons Attribution License
(CC BY). The use, distribution or reproduction
in other forums is permitted, provided the
original author(s) and the copyright owner(s)
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does not comply with these terms.
TYPE Original Research
PUBLISHED 04 October 2023
DOI 10.3389/fpsyg.2023.1158410
Winkelmair and Jansen 10.3389/fpsyg.2023.1158410
Frontiers in Psychology 02 frontiersin.org
transformations (Woiwode etal., 2021). A noteworthy contribution to
pro-environmental behavior at the individual level involves adopting
a sustainable diet. e production and consumption of food can
account for 19–29% of global anthropogenic greenhouse gas (GHG)
emissions (Vermeulen etal., 2012). Hence, the food sector represents
a decisive area for action, and the decision for a sustainable form of
nutrition signicantly contributes to personal sustainability. ere are
dierent ways of following a sustainable diet, like the preference for
organic, regional, or seasonal foods but also the reduction of animal
products such as meat (Von Koerber etal., 2017). However, according
to the United Nations, a global development towards a plant-based
diet can make a signicant contribution to saving the world from the
greatest damage of climate change (Alvaro, 2017). us, a vegetarian
or even vegan diet is considered a promising and benecial form of
sustainable nutrition. Meanwhile, it is widely acknowledged that
deciencies in protein, a signicant macronutrient in meat-based
diets, do not necessarily manifest in vegetarian or vegan diets.
Moreover, health benets seem to arise from plant-based protein
sources (Ewy et al., 2022). ere are various positive eects of
vegetarian nutrition—besides its lower environmental impact—such
as better physical health, more positive feelings for moral reasons, and
overall higher quality of life (Hargreaves etal., 2021). However, only
7% of the German population reported eating vegetarian (Statista,
2020). Accordingly, there is a high interest in promoting vegetarianism
and, thus, a promising way to eat sustainably. Current research
acknowledges the concept of mindfulness as a mechanism to foster
sustainable consumption behavior and lifestyle (e.g., Ericson etal.,
2014; Fischer et al., 2017; Geiger et al., 2020). Since most of the
previous studies showed only small eects and were cross-sectional
(Geiger et al., 2019), our study adds to this lack of research by
investigating the potential impact of dierent mindfulness
interventions on the aective attitudes toward vegetarian foods in a
randomized controlled longitudinal design.
Mindfulness can bedescribed as “the awareness that emerges
through paying attention on purpose, in the present moment, and
nonjudgmentally to the unfolding of experience moment by moment”
(Kabat-Zinn, 2003, p.145). It can beregarded in several ways: as a
state that can beachieved through meditation, a dispositional trait, a
type of meditation practice, or an intervention (Vago and Silbersweig,
2012). Mindfulness as a trait can beincreased by regular meditation
practice and thereby caused neuroplastic changes (Hölzel etal., 2011).
Dierent forms of meditation can beused as elements of mindfulness
interventions, such as attentional or constructive meditation practices,
according to the classication scheme of Dahl etal. (2015). Attentional
practices aim to train processes related to the regulation of attention
and strengthen the cognitive function for being aware of the processes
of thinking, feeling, and perceiving. It can bedierentiated between
focused-attention and open-monitoring practices. Focused-attention
practices involve a narrowing of the attentional scope and
concentration on one single object, such as breath counting (Lutz
etal., 2008). Open-monitoring practices involve an expansion of the
attentional scope and, thus, a ow of perceptions, thoughts, and
awareness. A well-established and evidence-based example of open-
monitoring meditation practice is the Mindfulness-based stress-
reduction (MBSR) program. In this intensive mindfulness training,
the individual learns to observe experiences instead of being wholly
immersed (Kabat-Zinn, 1982). It includes formal mindfulness
practices to increase attentional control and the non-judgmental
attitudinal aspects of mindfulness. Constructive meditation practices
strengthen psychological patterns that foster wellbeing by replacing
maladaptive self-schemes with more adaptive self-understandings.
In contrast to the attentional family, meditation forms of the
constructive family involve an active and systematic change in the
cognitive and aective contents instead of monitoring and simply
observing the present thoughts and emotions (Dahl etal., 2015). A
widely used form of meditation within the constructive family of
meditation forms is loving-kindness meditation (LKM; Lippelt etal.,
2014). LKM focuses on developing love for oneself, a beloved person,
a stranger, and a person one does not like. is style of practice can
enhance mindfulness as well as the awareness of the own environment.
With its focus on warm-heartedness, it can also increase positive
emotions, emotional wellbeing (Fredrickson etal., 2017), a sense of
connectedness toward others (Hutcherson et al., 2008), and
compassion (Luberto etal., 2018) and impact prosocial behavior
(Böckler etal., 2018).
e concept of mindfulness is discussed as a potential related
factor for sustainability in sustainable consumption research. A core
quality of mindfulness is the ability to disengage from an automated
thought-processing mode (Rosenberg, 2004) and enable more
conscious choices by the disruption of routines. Besides that, Fischer
et al. (2017) identied at least three other mechanisms of trait
mindfulness for sustainable consumption: congruence of attitude and
behavior, non-material values and wellbeing, and prosocial behavior.
However, in addition to its qualities of awareness, the gentle emotional
quality of mindfulness (Kabat-Zinn, 2003) that can beexperienced
through exercises of the constructive family such as LKM, can also
be seen in relation to sustainable consumption as it fosters
pro-environmental tendencies (Pfattheicher et al., 2016) and
sustainable decision making (Engel etal., 2020). As mentioned above,
the practice of LKM strengthens prosociality (Böckler etal., 2018) and
increases feelings of social connection (Hutcherson etal., 2008). ese
attributes, in turn, have been observed to belinked with sustainable
behavior (de Groot and øgersen, 2012). In the present study,
wefocus on the potential role of two conceptual dierent mindfulness
interventions—one rather cognitive, awareness focused and one
rather compassion oriented—for vegetarian food consumption.
e connection between mindfulness facets and sustainable
nutrition has been investigated in a few studies so far. For example,
Jacob etal. (2009) found a signicant link between sustainable food
practice and the frequency of mindfulness meditation. Hunecke and
Richter (2019) investigated the relation of ve dispositional
mindfulness facets (observing, describing, acting with awareness,
nonjudging of inner experience, nonreactivity to inner experience)
with the following constructs: construction of meaning in life,
sustainability-related meaning, personal ecological norm, and
sustainable food consumption. eir study revealed a direct
relationship between the mindfulness facet acting with awareness and
self-reported sustainable food consumption. An enhancement in this
dimension of mindfulness might thus support the choice of sustainable
food. However, this direct relation was only observed for sustainable
food choices but not for a vegetarian lifestyle which might bemore
inuenced by moral norms like animal welfare and ecological norms.
e follow-up study of Richter and Hunecke (2020) provides a
theoretical approach to how dierent dimensions of mindfulness and
the change process of human behaviors towards organic food
consumption are linked. eir model is based on the stage model of
Winkelmair and Jansen 10.3389/fpsyg.2023.1158410
Frontiers in Psychology 03 frontiersin.org
self-regulated behavioral change (SSBC) by Bamberg (2013), which
incorporates variables of the theory of planned behavior (Ajzen,
1991), the norm-activation model (Schwartz, 1977), and stages of
behavioral action adapted from the mindset theory of action phases
by Gollwitzer (1990). In the context of nutrition, the SSBC of Bamberg
(2013) has been applied to beef consumption by Klöckner (2017). is
investigation revealed attitudes as the main determinants for the
choice of an alternative behavior, e.g., the substitution of beef with
other meats or seafood, or vegetarian meals, and emphasizes the role
of social norms and the awareness of negative consequences of
behaviors through personal norms for the goal intention of reducing
beef consumption. In the framework of Richter and Hunecke (2020),
an adapted and reduced version of the SSBC by Bamberg (2013) was
used, comprising dierent types of intentions (goal intention, behavior
intention, implementation intention) and a xed sequence of stages
toward behavioral change (pre-decision, pre-action, action, and post-
action stages). ey include stage-specic variables that inuence
intentions and behavior such as social norms, personal norms,
attitudes, perceived behavior control, and dierent forms of self-
ecacy. eir cross-sectional online study revealed a signicant
relation between the mindfulness facet observing and goal intention
and an indirect eect on goal intention towards organic food
consumption, which was mediated by social and personal norms, and
explicit attitudes. e predictive value of personal and social norms,
attitudes, and perceived behavior control thus must beconsidered.
Siebertz et al. (2022) applied the adapted SSBC by Richter and
Hunecke (2020) in the context of vegetarian and vegan food
consumption and dispositional mindfulness. eir results showed that
the mindfulness facet observing correlated with the explicit attitudes
and goal intention and that personal norms mediated the link between
observing and goal intention. However, in the SSBC, only explicit
attitudes are considered. But besides these controlled-conscious
attitudinal aspects there is also an implicit, rather uncontrolled-
unconscious dimension of human attitudes as dual-process models
propose (Cameron etal., 2012). Combining both explicit and implicit
measurements can help reveal underlying attitudes and explain the
willingness for behavioral changes. By including implicit attitudes in
the model, the SSBC could benet from capturing not only self-
reports but also aspects that are rather unavailable to consciousness.
Conscious attitudes can be assessed through explicit
measurements, e.g., direct questions, whereas subconscious attitudes
require implicit measurements, like the aective priming task focusing
on the aective component of implicit evaluations. In this paradigm,
the response latency on a target stimulus aer the presentation of a
prime stimulus is measured (De Houwer et al., 2009). However,
research has proved that a person’s explicit and implicit attitudes are
not always related (Cameron etal., 2012). ere is a growing awareness
that individual consumption decisions are also inuenced by an
automatic, unconscious component (Panzone etal., 2016). Especially
in the eld of sustainability, considering both dimensions of attitudes
might be crucial as previous research revealed a low congruence
between explicit and implicit sustainability orientations (Steiner etal.,
2018). Consistent with this nding, Jansen etal. (2021) discovered a
more positive explicit attitude towards e-mobility compared to
gasoline cars, while no higher aective implicit rating could
beobserved. In the context of nutrition, previous research showed that
explicit attitudes toward vegetarian and vegan foods depend on the
preferred diet: Omnivores rated pictures of meat-based food as more
positive, and non-omnivores vegetarian and vegan food. Nevertheless,
all participants rated non-omnivorous food implicitly more positively
(Siebertz et al., 2022). In addition, another study using actual
supermarket shopping data could demonstrate that explicit and
implicit attitudes inuence consumer decisions dierently in specic
food categories (Panzone etal., 2016). ese ndings suggest that
research in sustainability and sustainable behavior could yield
important insights by exploring both explicit and implicit attitudes
and their (in)congruence (Steiner etal., 2018).
Mindfulness interventions might help to reconcile the
unconscious and conscious aspects of attitudes. Previous research
suggests that due to focusing on the current situation, mindfulness
meditation can reduce the impact of past experiences on the present
moment and therefore lead to reduced activation of automatic
associations (Lueke and Gibson, 2015). One central idea of
mindfulness is that it increases awareness of impulses, and while
accepting these events, a person can prevent automatically acting on
them. us, mindfulness has the potential to enhance controlled
processes while regulating automatic processes (Karremans and
Papies, 2017).
e main goal of this study was to investigate whether a cognitive
oriented mindfulness intervention and a compassion and caring-
based intervention that involves meditation forms of the constructive
family positively impact the explicit and implicit aective evaluations
of vegetarian foods as a form of sustainable nutrition. Weimplemented
two conceptual dierent mindfulness training programs: an adapted
MBSR training and a compassion and caring-based mental training
including LKM and aect dyads. As an active control group, a third
group received stress-reduction training. Since previous research
emphasizes the signicance of mediating factors in the relationship
between mindfulness and sustainable consumption, we included
possible inuencing variables such as wellbeing and compassion. Also,
weapplied the modied version of the SSBC of Richter and Hunecke
(2020) and investigated the role of explicit and implicit aective
attitudes for goal intention and their link to stage aliation towards a
vegetarian diet. Our hypotheses are as follows:
H1: First, since previous research showed a correlation between
mindfulness and aective attitudes (e.g., Jansen et al., 2021),
weassume that both the adapted MBSR and the compassion and
caring-based intervention groups improve the explicit and
implicit aective attitudes toward vegetarian foods compared to
the active control group. If the improvement is due to a change in
the daily awareness of impulses (Karremans and Papies, 2017;
Hunecke and Richter, 2019), it should be higher aer the
attention-focused meditation training (adapted MBSR) compared
to the compassion and caring-based mental training. On the other
hand, if the improvement is due to a change in the feeling of
connectedness to others (Hutcherson etal., 2008) and a higher
prosocial behavior (Böckler etal., 2018), it should bethe other
way around.
H2: According to Richter and Hunecke (2020), the behavioral
change toward sustainable food consumption follows a xed
sequence of stages. We, therefore, hypothesize that a higher stage
in the SSBC is linked to a more positive attitude toward
vegetarian food.
Winkelmair and Jansen 10.3389/fpsyg.2023.1158410
Frontiers in Psychology 04 frontiersin.org
H3: In the SSBC of Richter and Hunecke (2020), not only (explicit)
attitudes and the facets of mindfulness but also personal and
social norms are related to goal intention in the pre-decision stage.
For this, wewould like to investigate if mindfulness trainings
predict together with the attitudes toward vegetarian foods, social
and personal norms, a vegetarian diet, the dierent mindfulness
facets, compassion, and wellbeing the goal intention for a
vegetarian diet.
H4: In line with the results of Steiner etal. (2018), Jansen etal.
(2021), and Siebertz et al. (2022), we expect only a marginal
correlation between the explicit and implicit aective ratings in
the pre-test, if any. However, since mindfulness might bea factor
that could lead to reduced activation of automatic associations
(Lueke and Gibson, 2015), wehypothesize a stronger correlation
between the explicit and implicit aective attitudes aer
the interventions.
2. Materials and methods
2.1. Participants
Using G*power (Faul et al., 2007), power analysis for the
repeated measurements ANOVA within-between interaction
(within factor: three time points of measurement, between factor:
three groups) of our central hypothesis 1 was performed.
Consequently, with a small eect size of f = 0.15, a power of
1–ß = 0.80, and a standard alpha probability of 0.05, weaimed for a
total sample size of N = 93. Participants were recruited through the
institute of sports science newsletter at the University of Regensburg
and student groups on social media. Students of sports science
received course credit for their participation. However, there was
no academic connection between the investigator and the subjects
to control for possible social desirability eects. e study was
conducted in line with the ethical guidelines of the Helsinki
Declaration and approved by the ethics board of the University of
Regensburg (Reference number: 20-1740-101). It was preregistered
prior to data collection at OSF.1 All participants were informed and
gave their written consent. Wecollected the data of 119 participants
pre-intervention, 98 post-intervention, and 94 at the time of
follow-up measurement three months aer the intervention. Six
participants le the study between the pre-test and follow-up in the
compassion and caring-based mental training group, four in the
adapted MBSR group, and seven in the active control group. Eight
subjects le the study before the intervention groups were assigned.
e primary reasons for dropout during the 12-week intervention
groups were the change of study program, prolonged illness, and
lack of time for attending the weekly group sessions. In addition,
three more participants had to beexcluded due to more than 50%
incorrect responses in the aective priming task, resulting in a nal
1 https://osf.io/gbvua
sample size of 91 participants (compassion and caring-based mental
training group: N = 31, adapted MBSR group: N = 34, active control
group: N = 26) consisting of 54 women and 37 men (M age = 22.44,
SD = 2.39).
2.2. Procedure and design
2.2.1. Intervention
We implemented two conceptually dierent mindfulness
curriculums as interventions and an active control group. All three
programs consisted of 12 weekly group sessions á 75 min and weekly
homework assignments. To keep group sizes as small as possible,
wescheduled two groups at dierent times for each program, resulting
in subgroup sizes of between 17 and 21 participants. Experienced
trainers with specic mindfulness education taught all groups. No
sustainability-related content was discussed or implemented in any of
the groups.
2.2.1.1. Compassion and caring-based mental training
e core exercises of this curriculum were LKM (Salzberg, 2004)
and aected dyads. In LKM, the participants are introduced to a way
to oer love to themselves, other people, or animals. People are asked
to mentally repeat phrases like “May I/you behappy,” “May I/you
be healthy,” “May I/you be safe,” and “May I/you live with ease”
(Trautwein etal., 2020). Furthermore, aect dyad situations were
applied where partners sit face to face, and one partner contemplates
a situation to a specic theme of the main topics. e other partner
listens attentively without giving any verbal or non-verbal feedback.
Each session included a talk about a specic topic. e main subjects
of this course were breath, handling dicult emotions, the four
Buddhist Brahmaviharas, prosociality, compassion, appreciative joy,
equanimity, forgiveness, gratitude, and self-compassion. All sessions
followed a xed sequence of quiet time, check-in, talk, meditation,
exercise, homework, and check-out.
2.2.1.2. Adapted MBSR training
e adapted MBSR training was taught in line with the original
course of Kabat-Zinn (1990). e well-established curriculum
includes the following elements of meditation: body scan, mindful
eating, emphasizing the breath, and sitting and walking meditation
training. Every session contained a talk about specic topics such as
dierent forms of meditation and problems that may arise with them,
dierent levels of sensation during meditation, coping with complex
thoughts and feelings, being mindful of the body, and attentional
control. e focus of this mindfulness group was on the rather
cognitive elements of mindfulness and its qualities of awareness. In
line with the compassion and caring-based mental training
curriculum, all sessions followed the same xed sequence of quiet
time, check-in, talk, meditation, exercise, homework, and check-out.
2.2.1.3. Active control group
We implemented a stress-reduction program as an active control
group. is course taught progressive muscle relaxation (PMR), as it
had already been used in mindfulness research (Gao etal., 2018). e
curriculum was taught in line with the manual by Hofmann (2020) and
included training in lying, sitting, and imagination practice. ere was
no overlap in content between the active control group and the two
Winkelmair and Jansen 10.3389/fpsyg.2023.1158410
Frontiers in Psychology 05 frontiersin.org
mindfulness interventions, and strict consideration was given to avoid
any mindfulness-related exercises in this stress-reduction program.
2.2.2. Experimental pre/post/follow-up design
We applied a three (group: compassion and caring-based mental
training, adapted MBSR, active control group) x three (time: pre-test,
post-test, follow-up) design. Participants were randomly assigned to
one of the three groups. ey were unaware of their group assignment
and were instructed not to interact with other study participants of
the other two groups about the content of the group sessions.
Participants had to attend at least nine weekly meetings (this diers
from our preregistered exclusion criterium of the maximum of two
missing sessions, but wedecided to mitigate this criterium due to the
current Covid-19 situation). ere were three time points of
measurement: (1) within two weeks before starting of the intervention
groups (pre-test), (2) within two weeks aer the last group sessions
(post-test), and (3) around three months aer the last group sessions
(follow-up). Weincluded a follow-up measurement to assess longer-
term changes beyond the intervention sessions. Wechose a three-
month period as this period corresponds to the semester break and
thus the post-tests were conducted at the end of the semester and the
follow-up tests at the beginning of the new semester. e tests lasted
about 20 min each and included questionnaires presented via the
soware Sosci Survey (Leiner, 2019) and two tasks for measuring
explicit and implicit attitudes. Both tasks were programmed in
OpenSesame (Mathôt etal., 2012).
2.3. Measures
We reported McDonald’s Omega as an internal consistency index
and used the pre-test data (N = 119) for its calculation.
2.3.1. Demographic data
Questions concerning age, gender, education state, mother
tongue, regular occupation, and family status were asked.
Furthermore, the frequency and average duration in minutes of
practicing yoga and meditation were assessed during the pre-test. In
addition, questions regarding personal diet were asked: weregistered
eating habits (vegan, vegetarian, and omnivorous) and the personal
importance of the own nutrition at all three measurement times to
record change over the intervention. Last, wemeasured engagement
with the content of the groups beyond the weekly sessions in the form
of home assignments at the post-test and engagement with the
material aer the last group session at the follow-up measurement in
weekly minutes.
2.3.2. Goal intention, stage aliation, social and
personal norms
For the implementation of the SSBC, goal intention, social and
personal norms, according to Richter and Hunecke (2020), were
assessed at all three measurement times. Two items measured the goal
intention to eat more vegetarian meals (r = 0.84, p < 0.001) on a ve-
point Likert scale from 1 (“does not apply”) to 5 (“fully applies”). Also,
social norm—the attitude of people considered personally necessary
toward vegetarian meals—was measured by two items (r = 0.67,
p < 0.001) and personal norm, in the sense of the own values toward
vegetarian meals, by four items (ω = 0.80). e items of both norms
had to beanswered on a ve-point Likert scale from 1 (“does not
apply”) to 5 (“fully applies”). Wecalculated the mean value for goal
intention and social and personal norms for the corresponding items.
Furthermore, stage aliation was determined by one single-choice
item with four options, one option for each stage.
2.3.3. Mindfulness
Aspects related to mindfulness were measured by the German
Five Facets Mindfulness Questionnaire (FFMQ; Baer etal., 2008;
Michalak et al., 2016). e FFMQ comprises 39 items on ve
dimensions: observing (ω = 0.77; e.g., “I notice the smells and
aromas of things.”), describing (ω = 0.93; e.g., “I amgood at nding
words to describe my feelings.”), acting with awareness (ω = 0.86;
e.g., “I nd myself doing things without paying attention.” [R]),
nonjudging of inner experience (ω = 0.93; e.g., “I think some of my
emotions are bad or inappropriate, and Ishould not feel them.” [R])
and nonreactivity to inner experience (ω = 0.84; e.g., “I perceive my
feelings and emotions without having to react to them.”). All items
had to berated on a ve-point Likert scale from 1 (“applies very
rarely”) to 5 (“applies very oen”), and the mean values for all ve
scales were composed.
2.3.4. Compassion
Compassion was assessed using the Compassion Scale (CS;
Pommier et al., 2020). It comprises 16 items on four subscales:
kindness (e.g., “I like to bethere for others in times of diculty.”),
common humanity (e.g., “Everyone feels down sometimes, it is part
of being human.”), mindfulness (e.g., “I pay careful attention when
other people talk to me.”), and (inverted) indierence, separation, and
disengagement (e.g., “I do not concern myself with other people’s
problems.”, “I cannot really connect with other people when they are
suering.”, “I do not think much about the concerns of others.”). In the
present study, a translated German version applied by Siebertz etal.
(2022) was used. e participants stated how oen they feel or behave
in a specic way on a ve-point Likert scale from 1 (“almost never”)
to 5 (“almost always”). It should be noted that the CS subscale
mindfulness diers conceptually from mindfulness as it was assessed
by the FFMQ since its items concern interpersonal relationships in
contrast to the latter. Wecomputed the mean value of all 16 items
(ω = 0.72).
2.3.5. Wellbeing
Wellbeing was measured by the Brief Inventory of riving (BIT;
Su etal., 2014; Hausler etal., 2017). e BIT consists of ten items (e.g.,
“I amoptimistic about my future”) that had to beevaluated on a ve-
point Likert scale from 1 (“strongly disagree”) to 5 (“strongly agree”).
e mean value over all items was composed (ω = 0.80).
2.3.6. Explicit aective attitudes
We used an explicit aective evaluation task presenting ve
pictures of vegetarian foods and ve meat dishes in random order. e
pictures were derived from the food-pics extended image dataset
(Blechert et al., 2019) and were matched in terms of familiarity,
arousal, and valence using the ratings provided by the database. is
same set of pictures has been used in the study of Siebertz etal. (2022).
Also in line with the study design of Siebertz etal. (2022), weasked
the following question for each picture: “How much do youlike the
food in the picture?.” ey had to answer on a seven-point Likert scale
Winkelmair and Jansen 10.3389/fpsyg.2023.1158410
Frontiers in Psychology 06 frontiersin.org
from 1 (“not at all”) to 7 (“very much”) within 5 s to assess their
spontaneous reaction. e mean scores for the explicit rating of
vegetarian and meat-based foods were calculated.
2.3.7. Implicit aective attitudes
An aective priming paradigm (Fazio etal., 1995; Hutcherson
etal., 2008) using the same pictures of the explicit evaluation task was
applied. We implemented a short practice trial with four other
non-food-related pictures before the central part of the task started.
First, an initial xation point was shown for 2000 ms in the center of
the screen. Aer this, a picture of either a vegetarian or a meat dish
appeared briey for 315 ms. Aer another xation point for 135 ms, a
word picked randomly from a pool of four positive and four negative
words retrieved from the Berlin Aective Word List (BAWL-R; Võ
etal., 2009) was shown. e participants had to decide whether the
shown word was positive or negative via the arrow keys and react as
quickly as possible since the word disappeared aer 1750 ms, see
Figure1. Each picture was combined with each word, resulting in 80
trials. If participants skipped a trial by answering too slowly, the trial
with its respective picture-word combination was repeated at the end
of the task. On average, over the 80 trials, M = 4.69 (SD = 9.15) in the
pre-test, M = 2.66 (SD = 5.07) in the post-test, and M = 2.16 (SD = 2.43)
in the follow-up, had to beimputed due to incorrect or too fast (below
100 ms) responses. Aer checking visually that empty values were
missing at random, they were imputed by multiple imputation
algorithms and pooling means. Subsequently, reaction times when
categorizing picture-primed positive words were subtracted from
reaction times when categorizing picture-primed negative words,
separately for both picture categories and averaged, respectively. us,
a higher dierence score reected a more positive attitude.
2.3.8. Personal evaluation of sustainability
e participants had to indicate on a seven-point Likert scale
from 1 (“not at all”) to 7 (“very much”) how sustainable they evaluated
the vegetarian and meat dishes shown in the pictures used in the
explicit aective evaluation task and the aective priming paradigm.
Weseparately composed the mean value for the vegetarian (ω = 0.68)
and the meat-based (ω = 0.82) food pictures.
2.4. Statistical analysis
A three (time: pre-test, post-test, follow-up) x three (group:
compassion and caring-based mental training, adapted MBSR, active
control group) ANOVA with repeated measurements was conducted
to nd out if the intervention groups had an impact on the explicit and
implicit aective attitudes toward vegetarian foods (hypothesis 1). To
analyze if stage aliation aects the explicit and implicit aective
attitudes toward vegetarian foods (hypothesis 2), two one-way
ANOVAs with stage aliation as an independent variable were
performed for all three measurements. Multiple linear regression
analyses for the post-test and follow-up measurement were calculated
for the dependent variable goal intention and the following predictors
(hypothesis 3): group (compassion and caring-based mental training,
adapted MBSR, active control group), explicit and implicit aective
attitudes toward vegetarian foods, social norm, personal norm,
vegetarian/vegan diet, the aspects of mindfulness (observing,
nonreactivity, acting with awareness, nonjudging, describing),
compassion and wellbeing. To account for multicollinearity, variance
ination factors (< 2.05) and tolerance (> 0.48) were considered and
regarded as appropriate (O’Brien, 2007). e correlations between the
explicit and implicit aective attitudes were calculated for all three
measurement times (pre-test, post-test, and follow-up) and both food
categories separately (hypothesis 4). Weconducted a matched-pairs
t-test to test whether there was a dierence between the explicit rating
of vegetarian and meat-based foods. Likewise, to analyze if there was
a dierence between the implicit aective ratings of meat and
vegetarian foods, another matched-pairs t-test was performed for the
reaction time dierence score between negative and positive words.
Last, weperformed another matched-pairs t-test to test whether there
was a dierence in the personal evaluation of sustainability between
the two categories of vegetarian and meat-based foods. Exploratorily,
a possible change in mindfulness, compassion, and wellbeing due to
the intervention was examined. e Greenhouse–Geisser adjustment
was used for relevant results to correct for violations of sphericity.
Analyses were performed using IBM Statistics SPSS 28.
3. Results
3.1. Demographic data
Age, education state, frequency of practicing meditation and yoga
(at pre-test), as well as done home assignments (at post-test), and
engagement with the contents of the group aer the last session (at
follow-up) are shown separately for each the three intervention groups
in Table 1. e age of the participants diered between the three
groups, χ
2
(2) = 9.72, p = 0.008, as well as the number of attended group
sessions (compassion and caring-based mental training group:
M = 10.29, SD = 0.74, adapted MBSR group: M = 10.44, SD = 0.89,
active control group: M = 9.85, SD = 0.63; χ
2
(2) = 8.28, p = 0.016), but
with no dierence between the two mindfulness intervention groups.
FIGURE1
Procedure of the implicit aective priming task.
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Frontiers in Psychology 07 frontiersin.org
In addition, eating habits (vegetarian/vegan, omnivorous), the
importance of their nutrition, and the three highest-rated reasons if a
vegetarian/vegan diet was chosen are presented in Table 2 over all
three points of measurement separately for the three groups.
3.2. Eects of groups on the explicit and
implicit aective attitudes toward
vegetarian foods (hypothesis 1)
e repeated measure ANOVA for the explicit aective attitudes
toward the vegetarian dishes showed a signicant main eect of time,
F(1.74, 152.82) = 4.43, p = 0.017, partial η
2
= 0.048. ere was no main
eect of group (F(2, 88) = 0.60, p = 0.552), as well as no signicant
interaction between time and group (F(3.47, 152.82) = 1.21, p = 0.346).
Subsequent performed Bonferroni-adjusted matched-pairs t-tests
(p < 0.017) revealed a signicant dierence between the explicit attitudes
in the pre-test and post-test, t(90) = −3.12, p = 0.001, 95% CI [−0.42,
−0.09], d = 0.79, as well as pre-test and follow-up, t(90) = −2.20,
p = 0.015, 95% CI [−0.46, −0.02], d = 1.06, but not between post-test and
follow up, t(90) = 0.15, p = 0.441, see Figure2. e repeated measure
ANOVA for the implicit rating revealed no main or interaction eects.
3.3. Stage aliation and explicit and
implicit aective attitudes toward
vegetarian foods (hypothesis 2)
In all three measurements, the explicit aective attitudes toward
vegetarian foods descriptively were more positive the “higher” the stage
of the participants (see Table3). Regarding the implicit attitudes, the
same tendency could benoted with one exception in the follow-up (see
Table4). e one-way ANOVA with stage aliation as an independent
variable revealed a signicant dierence regarding the explicit aective
attitudes toward the vegetarian dishes between the dierent levels of
stage aliation in the pre-test, F(3, 87) = 4.70, p = 0.004, partial η
2
= 0.140,
the post-test, F(3, 87) = 5.79, p = 0.001, partial η
2
= 166, and in the
follow-up, F(3, 87) = 9.42, p < 0.001, partial η
2
= 0.245. Turkey post-hoc
analyses revealed a signicant dierence between pre-decision and
post-action stages (pre-test: −0.97, p = 0.017, 95% CI [−1.81, −0.13],
post-test: −1.19, p = 0.004, 95% CI [−2.07, −0.30], follow-up: −1.57,
p < 0.001, 95% CI [−2.56, −0.58]) and pre-action and post-action stages
(pre-test: −0.84, p = 0.039, 95% CI [−1.65, −0.32], post-test: −1.09,
p = 0.040, 95% CI [−2.14, 0.55], follow-up: −1.45, p = 0.001, 95% CI
[−2.44, −0.46]). ere were no signicant dierences regarding implicit
aective attitudes in all three measurements.
3.4. Eects of groups, attitudes, social and
personal norms, vegetarian diet,
mindfulness facets, compassion, wellbeing
on the goal intention (hypothesis 3)
e results of the multiple regression analysis for goal intention
in the post-test showed that 82% (adjusted R2 = 0.61) of the variance
is explained, F(14, 76) = 11.01, p < 0.001, with the two signicant
predictors personal norm and vegetarian/vegan diet (see Table5a).
In the multiple regression analysis in the follow-up, 86% (adjusted
R
2
= 0.68) of the variance is explained with the model, F(14,
76) = 14.87, p < 0.001. Besides personal norms and a vegetarian/
vegan diet, social norm was the third signicant predictor (see
Table5b).
TABLE1 Mean (SD) of age, meditation, and yoga practice (min per year), home assignments and engagement with content of group after the last
session (min per week), and relative frequency of education state, yoga, and meditation practice for each group.
AgeaEducationaMeditation practice
(min/year)a
Yoga practice
(min/year)a
Home
assignments
(min/week)b
Engagement
since last session
(min/week)c
Compassion and
caring-based
mental training
(N = 31)
23.65 (3.23)
High School: 90.3%
Bachelor: 6.5%
Master: 3.2%
418.87 (1022.84)
Never: 6.5%
Once: 48.4%
Sometimes/year: 16.1%
Sometimes/month: 25.8%
Daily: 3.2%
1170.48 (2279.37)
Never: 6.5%
Once: 29.0%
Sometimes/year: 29.0%
Sometimes/month: 29.0%
Daily: 6.5%
32.45 (44.46) 15.00 (25.63)
Adapted MBSR
training (N = 34) 21.94 (3.77) High School: 97.1%
Master: 2.9%
391.91 (1022.54)
Never: 8.8%
Once: 52.9%
Sometimes/year: 11.8%
Sometimes/month: 23.5%
Daily: 2.9%
1559.41 (3140.73)
Never: 8.8%
Once: 35.3%
Sometimes/year: 17.6%
Sometimes/month: 23.5%
Daily: 14.7%
20.15 (33.68) 17.65 (32.18)
Active control
group (N = 26) 21.65 (2.21) High School:
100.0%
220.96 (502.30)
Never: 7.7%
Once: 57.7%
Sometimes/year: 15.4%
Sometimes/month: 15.4%
Daily: 3.8%
1550.96 (3643.67)
Never: 11.5%
Once: 34.6%
Sometimes/year: 23.1%
Sometimes/month: 19.2%
Daily: 11.5%
16.54 (16.84) 7.88 (12.26)
ameasured at pre-test.
bmeasured at post-test.
cmeasured at follow-up.
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3.5. Correlations between explicit and
implicit aective attitudes toward
vegetarian and meat-based foods
(hypothesis 4)
ere was a signicant correlation between the explicit aective
attitudes and the implicit aective attitudes toward vegetarian meals
in the pre-test, r = 0.27, p = 0.011, but neither in the post-test (r = 0.16,
p = 0.121) nor follow-up (r = −0.04, p = 0.719). ere was no correlation
between the explicit and implicit aective attitudes toward the meat
dishes (pre-test: r = 0.06, p = 0.600; post-test: r = 0.06, p = 0.600;
follow-up: r = 0.04, p = 0.701).
3.6. Dierence between explicit and
implicit aective attitudes toward
vegetarian and meat-based foods
e paired t-test revealed a signicant dierence between explicit
aective attitudes toward vegetarian and meat dishes in the pre-test
(vegetarian: M = 4.34, SD = 1.02; meat: M = 3.40, SD = 1.79),
t(90) = 3.90, p < 0.001, 95% CI [0.46, 1.42], post-test (vegetarian:
M = 4.59, SD = 1.15; meat: M = 3.28, SD = 1.74), t(90) = 5.07, p < 0.001,
95% CI [0.80, 1.82], and at the time of the follow-up test (vegetarian:
M = 4.58, SD = 1.26; meat: M = 3.11, SD = 1.65), t(90) = 5.65, p < 0.001,
95% CI [0.96, 1.99]. Another paired t-test also resulted in a signicant
dierence between implicit aective attitudes toward vegetarian and
meat dishes in the pre-test (vegetarian: M = 23.74, SD = 70.04; meat:
M = −15.44, SD = 86.97), t(90) = 3.40, p = 0.001, 95% CI [16.28, 62.07],
post-test (vegetarian: M = 11.09, SD = 60.31; meat: M = −4.55,
SD = 75.61), t(90) = 1.70, p = 0.047, 95% CI [−2.69, 33.96] and at the
time of the follow-up test (vegetarian: M = 19.04, SD = 58.34; meat:
M = 1.17, SD = 56.38), t(90) = 2.42, p = 0.009, 95% CI [3.20, 32.53]. e
explicit and implicit aective attitudes toward the pictures of the
vegetarian dishes were more positive than toward the meat pictures,
with a small to medium eect size for the explicit attitudes (pre-test:
d = 0.41, post-test: d = 0.53, follow-up: d = 0.59) and small eect size for
the implicit attitudes (pre-test: d = 0.36, post-test: d = 0.18, follow-up:
d = 0.25).
TABLE2 Mean (SD) of importance of nutrition and three highest rated reasons for a chosen vegetarian/vegan diet and relative frequency of eating
habits for each group.
Pre-test Post-test Follow-up
Eating
habit
Importance
nutritiona
Reasons
for veg
dieta, b
Eating
habit
Importance
nutritiona
Reasons
for veg
dieta, b
Eating
habit
Importance
nutritiona
Reasons
for veg
dieta, b
Compassion
and caring-
based
mental
training
(N = 31)
Vegetarian/
vegan:
35.5% (11)
Omnivore:
64.5% (20)
4.39 (0.62)
Sustainability:
4.45 (0.93)
Health: 4.18
(1.08)
Moral: 4.09
(0.83)
Vegetarian/
vegan:
41.9% (13)
Omnivore:
58.1% (18)
4.35 (0.55)
Sustainability:
4.54 (0.66)
Moral: 4.15
(0.80)
Health: 3.92
(1.44)
Vegetarian/
vegan:
35.5% (11)
Omnivore:
64.5% (20)
4.35 (0.66)
Sustainability:
4.91 (0.30)
Moral: 4.36
(0.81)
Health: 4.27
(1.01)
Adapted
MBSR
training
(N = 34)
Vegetarian/
vegan:
44.1% (15)
Omnivore:
55.9% (19)
4.38 (0.65)
Sustainability:
4.20 (1.01)
Moral: 4.00
(1.20)
Health: 4.00
(0.93)
Vegetarian/
vegan:
50.0% (17)
Omnivore:
50.0% (17)
4.35 (0.69)
Sustainability:
4.24 (0.66)
Health: 4.18
(0.73)
Moral: 4.12
(0.93)
Vegetarian/
vegan:4.1%
(15)
Omnivore:
55.9% (19)
4.32 (0.73)
Sustainability:
4.33 (0.72)
Moral: 4.33
(0.72)
Health: 4.33
(0.72)
Active
control
group
(N = 26)
Vegetarian/
vegan:
30.8% (8)
Omnivore:
69.2% (18)
4.08 (0.69)
Sustainability:
4.38 (0.74)
Health: 4.38
(0.52)
Moral: 4.25
(0.71)
Vegetarian/
vegan:
42.3% (11)
Omnivore:
57.7% (15)
4.12 (0.77)
Moral: 4.36
(1.03)
Sustainability:
4.27 (0.79)
Health: 4.09
(0.94)
Vegetarian/
vegan:
42.3% (11)
Omnivore:
57.7% (15)
4.27 (0.72)
Moral: 4.55
(0.69)
Sustainability:
4.09 (0.83)
Health: 3.73
(0.79)
ascale from 1 (“not at all”) to 5 (“very much”).
bif vegetarian or vegan was specied at “Eating habit”.
FIGURE2
Means (SE) of the explicit aective attitudes toward vegetarian and
meat-based foods in pre-test, post-test, and follow-up.
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3.7. Rating of sustainability of the
vegetarian and meat foods
ere was a signicant dierence between the personal evaluation
of sustainability between the vegetarian and meat foods at the pre-test
(vegetarian: M = 6.08, SD = 0.59; meat: M = 1.65, SD = 0.65),
t(90) = 50.50, p < 0.001, 95% CI [4.25, 4.60], post-test (vegetarian:
M = 6.15, SD = 0.53; meat: M = 1.55, SD = 0.58), t(90) = 60.13, p < 0.001,
95% CI [4.44, 4.75], and at the time of the follow-up test (vegetarian:
M = 6.09, SD = 0.58; meat: M = 1.57, SD = 0.59), t(90) = 52.09, p < 0.001,
95% CI [4.35, 4.70]. is indicates a higher sustainability evaluation
for the vegetarian dishes with a medium to large eect size for the
three measurement time points (pre-test: d = 0.84, post-test: d = 0.73,
follow-up: d = 0.83).
3.8. Exploratory analysis
In an exploratory manner, weinvestigated whether there were
changes in mindfulness (FFMQ), compassion (CS), and wellbeing
(BIT) between the pre-test and post-test, dependent on the
intervention group. Regarding mindfulness, a repeated measure
ANOVA showed only an eect for the factor time, F(1, 88) = 8.61,
p = 0.004, part ial η
2
= 0.089, but not for group, F(2, 88) = 0.03, p = 0.966,
partial η
2
= 0.001 or the interaction between time and group, F(2,
88) = 1.38, p = 0.257, partial η
2
= 0.030. e mindfulness score was
higher in the post-test (M = 3.30, SD = 0.50) compared to the pre-test
(M = 3.40, SD = 0.51). No signicant changes in compassion and
wellbeing depended on time, group, or the interaction of time and
group. Furthermore, there was no correlation between the dierence
of the pre- and post-test in the explicit attitudes toward vegetarian
food and the change in mindfulness over time, r = 95% CI [−0.10,
0.31]. Wefurther investigated whether the interventions impacted the
explicit aective attitudes toward meat-based foods. e repeated
measure ANOVA showed a signicant main eect of time, F(1.81,
159.40) = 5.44, p = 0.007, partial η
2
= 0.058, but neither a main eect of
group (F(2, 88) = 0.14, p = 0.870) nor a signicant interaction between
time and group (F(3.62, 159.40) = 1.19, p = 0.315). Post-hoc Bonferroni-
adjusted matched-pairs t-tests (p < 0.017) revealed a signicant
dierence between pre-test and follow-up, t(90) = 2.76, p = 0.003, 95%
CI [0.08, 0.50], d = 1.01, as well as post-test and follow-up, t(90) = 2.23,
p = 0.014, 95% CI [0.02, 0.33], d = 0.75 (see Figure2).
In an additional exploratorily analysis, we also considered
potential gender dierences in the explicit aective attitudes. An
independent sample t-test revealed no signicant dierences between
women and men in their explicit aective attitudes toward vegetarian
foods during the pre-test. However, there were dierences at the time
of post-testing with more positive attitudes in women (M = 4.89,
SD = 1.10) compared to men (M = 4.17, SD = 1.09), t(89) = −3.06,
p = 0.003, 95% CI [−1.18, −0.25], d = −0.65. Regarding explicit
attitudes toward meat-based foods, the pattern was reversed, with
signicant gender discrepancies in both pre-test (Z = −4.11, p < 0.001,
Spearman’s ρ = −0.43) and post-test (Z = −3.89, p < 0.001, Spearman’s
ρ = −0.41), as demonstrated by a Wilcoxon-Mann–Whitney test. Men
showed more positive attitudes (pre-test: M
Rank
= 59.70, post-test:
M
Rank
= 58.96) than women (pre-test: M
Rank
= 36.61, post-test:
MRank = 37.12).
4. Discussion
e results showed that the explicit rating of the vegetarian foods
increased signicantly between pre-test and post-test, and pre-test and
follow-up regardless of the assigned group. ere were no signicant
changes in the implicit attitudes toward the vegetarian pictures.
Including the SSBC, our results revealed a signicant dierence in the
explicit aective attitudes toward vegetarian foods depending on stage
aliation between the pre-decision and post-action stages and the
pre-action and post-action stages at all three testing times.
Nevertheless, no such connection could befound for the implicit
measurements. Also contrary to our assumptions, the multiple
regression model identied only two signicant predictors for goal
TABLE3 Explicit aective attitudes toward vegetarian foodsa in the self-regulated behavioral change (SSBC).
Pre-test Post-test Follow-up
Stage Stage aliation N M SD N M SD N M SD
Pre-decision
My meals oen contain meat-based
foods, and Ido not intend to change
that in the future.
11 3.64*,1 0.96 12 3.7*,3 1.28 10 3.4*,5 1.42
Pre-action
ese days I’m thinking about eating
vegetarian meals more oen instead
of meat-based ones, but Ido not
know exactly how to implement that
yet.
12 3.77*,2 1.05 8 3.8*,4 0.83 10 3.52*,6 1.05
Action
I’ve decided to eat vegetarian instead
of meat-based meals more oen in
the future, and I’ve already educated
myself on how to make that happen.
15 4.35 0.84 11 4.46 0.96 9 4.38 0.85
Post-action
I prefer to eat vegetarian instead of
meat-based meals as oen as possible
and will maintain this in the future.
53 4.61*,1,2 0.98 60 4.89*,3,4 1.07 62 4.97*,5,6 1.1
ascale from 1 (“not at all)” to 5 (“very much”).
*signicant dierence p < 0.05, superscript numbers (1–6) denote the respective signicantly dierent means.
Winkelmair and Jansen 10.3389/fpsyg.2023.1158410
Frontiers in Psychology 10 frontiersin.org
intention in the post-test: personal norm and a vegetarian/vegan diet.
In addition to these two factors, the relation between social norms and
goal intention was also signicant at the follow-up. Last, in
contradiction to the fourth hypothesis, we found a signicant
correlation between the explicit and implicit aective attitudes toward
vegetarian foods in the pre-test but neither in the post-test and
follow-up nor between the explicit and implicit aective attitudes
toward the meat-based dishes.
4.1. Intervention groups and explicit and
implicit aective attitudes toward
vegetarian foods
As stated, the intervention eect towards a more favorable
rating of vegetarian foods was rather general and unrelated to the
assigned intervention. Neither the adapted MBSR and the
compassion and caring-based as mindfulness interventions nor the
stress-reduction program of the active control group seem more
suitable for improving the explicit attitudes toward vegetarian
foods. A possible explanation is that these attitudinal changes are
attributed to the general engagement with oneself every week for
75 min, 12 weeks long, and not specic mindfulness practice. By
taking time for themselves in stressful everyday life—whether in a
mindfulness course or stress-reduction training—participants
reect, connect with themselves on a deeper level, and might set
inner transformations in motion. According to Woiwode et al.
(2021, p.853), “inner dimensions and transformation are essential
to understand and facilitate personal and collective processes of
change in terms of our awareness and relationship to ourselves,
others, and the environment.” Another interesting (exploratory)
result is that the interventions seem to have aected the explicit
aective attitudes toward meat-based foods. However, in contrast
to the attitudes toward vegetarian dishes, the rating decreased over
time. Again, this eect of the intervention was independent of the
assigned group. Both conceptually dierent mindfulness
interventions and the PMR training thus might not only improve
the explicit attitudes toward vegetarian foods but also worsen the
attitudes toward meat dishes which is also benecial for the choice
of a sustainable diet. Our exploratory analysis showed an
improvement in mindfulness measured by the FFMQ in both
mindfulness intervention groups, which can beconsidered a control
measure for the eectiveness of the curriculums. However, the
mindfulness score also increased in the active control group over
time. is is consistent with previous research that indicates that
although mindfulness is a mechanism specic to mindfulness
interventions like MBSR, stress-reduction programs such as PMR
can also improve mindfulness (e.g., Agee etal., 2009; Gao etal.,
2018). An explanation for this result is that there are some
overlapping aspects of PMR and mindfulness curriculums like
MBSR, as both programs incorporate components that cultivate
attentional processes. In PMR, the participants are guided to focus
attention on specic muscle groups and their contraction and
relaxation. ough achieved through physical rather than mental
exercise, the concentration on the present moment is quite similar
to the key elements of MBSR, like awareness of the present moment
and attentional control. However, the changes in the explicit
attitudes and the mindfulness score did not correlate. In addition,
there were no positive changes in wellbeing for both mindfulness
interventions and the active control group. is null eect
contradicts previous ndings that mindfulness interventions aect
personal wellbeing (Geiger etal., 2020) and questions wellbeing as
a mechanism for the relation between mindfulness and sustainable
consumption in the context of vegetarian food (Fischer etal., 2017).
Also, contradictory to previous research showing that LKM may
enhance compassion (Luberto et al., 2018), there was no
enhancement of compassion in the compassion training group. One
reason might bethat the intervention time of 12 weekly sessions of
75 min was too short and not intensive enough to change wellbeing
and compassion. For instance, in the study of Trautwein et al.
(2020), the training modules lasted for three months and included
a three days long intensive retreat, 13 weekly group sessions á
120 min, as well as daily home exercises with audio streams for
guided meditations and an interface for the dyadic exercises on an
internet platform and smartphone applications. Another possible
explanation worth considering is that there might be a third
standard set of factors related to mindfulness and sustainable
behavior (Geiger etal., 2020) or sustainable nutrition in particular.
TABLE4 Implicit aective attitudes toward vegetarian foodsa in the self-regulated behavioral change (SSBC).
Pre-test Post-test Follow-up
Stage Stage aliation N M SD N M SD N M SD
Pre-decision My meals oen contain meat-based foods, and
Ido not intend to change that in the future. 11 −17.28 44.49 12 −16.7 90.44 10 −5.38 32.35
Pre-action
ese days I’m thinking about eating
vegetarian meals more oen instead of meat-
based ones, but Ido not know exactly how to
implement that yet.
12 24.31 56.85 8 −11.4 40.96 10 19.72 82.56
Action
I’ve decided to eat vegetarian instead of meat-
based meals more oen in the future, and I’ve
already educated myself on how to make that
happen.
15 29.26 51.15 11 8.55 30.55 9 32.08 76.88
Post-action
I prefer to eat vegetarian instead of meat-based
meals as oen as possible and will maintain
this in the future.
53 30.55 79.44 60 20.11 57.94 62 20.98 54.4
aRTpicture-primed negative words—RTpicture-primed positive words; the higher the value, the more positive the attitude.
Winkelmair and Jansen 10.3389/fpsyg.2023.1158410
Frontiers in Psychology 11 frontiersin.org
For example, Wamsler et al. (2021) mention ve internal
transformative qualities—awareness, connections, insight, purpose,
and agency—that might mediate the relationship between
mindfulness and pro-environmental behavior.
TABLE5a Regression-analysis with the criterion goal intention in the post-test.
Goal intention (post-test)
Variable (post-test) b SE βt p 95% CI
Compassion and caring-based
mental traininga−0.13 0.22 −0.05 −0.58 0.567 [−0.56, 0.31]
Adapted MBSR traininga−0.02 0.22 −0.01 −0.10 0.919 [−0.46, 0.42]
Explicit attitudes toward vegetarian
food 0.09 0.09 0.08 1.00 0.320 [−0.09, 0.26]
Implicit attitudes toward vegetarian
food 0.00 0.00 0.02 0.34 0.734 [0.00, 0.00]
Social norm 0.04 0.10 0.04 0.43 0.669 [−0.15, 0.23]
Personal norm 0.62 0.12 0.49 5.27 < 0.001 [0.38, 0.85]
Compassion (CS) 0.13 0.26 0.04 0.50 0.622 [−0.40, 0.66]
Wellbeing (BIT) 0.08 0.18 0.04 0.44 0.658 [−0.28, 0.44]
Nonjudging of inner experience
(FFMQ) 0.17 0.12 0.13 1.43 0.157 [−0.07, 0.42]
Describing (FFMQ) 0.04 0.12 0.03 0.36 0.722 [−0.20, 0.28]
Observing (FFMQ) 0.05 0.17 0.02 0.28 0.782 [−0.29, 0.38]
Acting with awareness (FFMQ) −0.09 0.16 −0.05 −0.56 0.576 [−0.40, 0.23]
Nonreactivity (FFMQ) −0.03 0.15 −0.02 −0.20 0.840 [−0.33, 0.27]
Vegetarian/vegan diet 0.80 0.21 0.33 3.82 < 0.001 [0.38, 1.22]
aReference group: Active control group.
TABLE5b Regression-analysis with the criterion goal intention in the follow-up.
Goal intention (follow-up)
Variable (follow-up) b SE βt p 95% CI
Compassion and caring-based
mental traininga
−0.28 0.19 −0.11 −1.47 0.147 [−0.66, 0.10]
Adapted MBSR traininga−0.11 0.19 −0.05 −0.58 0.561 [−0.49, 0.27]
Explicit attitudes toward vegetarian
food
0.13 0.08 0.14 1.65 0.102 [−0.03, 0.29]
Implicit attitudes toward vegetarian
food
0.00 0.00 0.06 0.96 0.343 [0.00, 0.00]
Social norm 0.21 0.08 0.20 2.79 0.007 [0.06, 0.36]
Personal norm 0.57 0.11 0.43 5.06 < 0.001 [0.34, 0.79]
Compassion (CS) 0.13 0.24 0.04 0.55 0.585 [−0.34, 0.60]
Wellbeing (BIT) 0.11 0.18 0.05 0.61 0.544 [−0.24, 0.46]
Nonjudging of inner experience
(FFMQ)
−0.03 0.01 −0.03 −0.35 0.731 [−0.23, 0.16]
Describing (FFMQ) 0.09 0.01 0.07 0.93 0.353 [−0.10, 0.29]
Observing (FFMQ) −0.18 0.15 −0.09 −1.25 0.214 [−0.47, 0.11]
Acting with awareness (FFMQ) 0.19 0.15 0.11 1.28 0.205 [−0.11, 0.50]
Nonreactivity (FFMQ) −0.09 0.13 −0.05 −0.70 0.486 [−0.36, 0.17]
Vegetarian/vegan diet 0.69 0.19 0.28 3.54 < 0.001 [0.30, 1.07]
aReference group: Active control group.
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Frontiers in Psychology 12 frontiersin.org
4.2. Implementation of the SSBC
Regarding the SSBC, our results conrm the plausibility of the
suggested sequence in the vegetarian context: the explicit aective
attitudes were descriptively more positive the higher the stage in the
model. According to Richter and Hunecke (2020), people in the rst
stage—the pre-decision stage—might have no problem awareness of
their environmentally harmful behavior and, thus, no plan to change
their diet. In the second stage, the pre-action, awareness for a
necessary change is formed, but there is no concrete plan for
implementation, as this concretization comes only in the action
phase. In this stage, people have planned the time and realization of
their new behavior. Last, the change is accomplished in the post-
action stage and the new behavior has become a new habit. Wefound
a signicant dierence in the explicit aective attitudes between the
stages pre-decision and post-action, as well as pre-action and post-
action. is link between attitudes toward vegetarian foods and an
actual implemented vegetarian diet again highlights the importance
of human attitudes for sustainable behavior, especially when
comparing earlier stages of behavioral change and the post-action
phase. is development was not reected in the implicit attitudes, at
least statistically. However, it is in line with the study of Siebertz etal.
(2022), who also did not nd any evidence for a possible role of
implicit attitudes in the SSBC toward vegetarian and vegan nutrition.
Does this mean implicit attitudes are irrelevant to the behavioral
change towards a vegetarian diet? Before making such a signicant
conclusion, it is worth using other implicit measurements in further
studies. In the SSBC, attitudes, social, and personal norms are stage-
specic variables for goal intention in the pre-decision stage.
Nevertheless, attitudes did not predict goal intention in our study. A
reason for this might bethe dierent ratings of explicit attitudes. In
our study, participants had to explicitly rate pictures of vegetarian and
vegan food. In the study of Richter and Hunecke (2020), they had to
complete a questionnaire. Food pictures draw attention and activate
brain areas related to reward, salience, and cognitive control (Blechert
etal., 2019). is is not the case for questionnaires. ere was no
relationship between any of the mindfulness facets and goal intention,
which contradicts previous studies that showed a relation between
the mindfulness aspect of observing and goal intention (Richter and
Hunecke, 2020; Siebertz et al., 2022) and describing and goal
intention (Richter and Hunecke, 2020). However, this emphasizes the
importance and predictive value of one’s social and personal norms.
is result strengthens the normative pathway in the two-pathway
model of pro-environmental behavior (iermann and Sheate, 2020).
Nevertheless, people’s values and personal attitudes are part of the
inner transformation concept. is nding again highlights the
relevance of inner dimensions for sustainability (Woiwode
etal., 2021).
4.3. Explicit and implicit aective attitudes
toward vegetarian foods
We compared the explicit and implicit aective attitudes toward
pictures of either vegetarian or meat-based foods. Participants rated
explicitly and implicitly vegetarian dishes more positive than the
foods based on meat at all three measurements before and
independent of the assigned intervention group. is is in line with
previous results regarding the nutrition-related sustainability of
Siebertz et al. (2022). In this study, non-omnivore participants
evaluated explicitly and implicitly vegetarian compared to meat-
based foods more positively. e dierentiation between vegetarian
and omnivore could not beconducted in the study presented here
due to the relatively small number of participants. e individual
rating of sustainability of the shown dishes revealed that the
vegetarian dishes were estimated to bemore sustainable than the
meat foods, suggesting that the attitudes toward vegetarian and
sustainable foods could have been investigated. However, among the
participants that followed a vegetarian or vegan diet, the three most
reported reasons for their eating behavior choices were sustainability,
morale, and health. Hopwood etal. (2020) identied health as the
most common motive for non-vegetarians to consider a vegetarian
diet. Further individual characteristics of vegetarians can begender,
age, education, and income, such as personality traits (Pfeiler and
Eglo, 2018). erefore, the motives for maintaining a vegetarian or
vegan lifestyle are manifold and may becomplex. us, the more
positive attitude toward vegetarian dishes cannot beattributed clearly
to the perceived sustainability of the shown foods. Contrary to our
fourth hypothesis, there was a correlation between the explicit and
implicit evaluations of vegetarian foods in the pre-test but not in the
post-test and follow-up. e lack of correlation is in line with
previous ndings that suggested a low congruence between the
explicit and implicit attitudes in the context of sustainability (Steiner
etal., 2018; Jansen etal., 2021). However, weassumed there might
be a congruence aer the mindfulness intervention groups since
mindfulness could reduce the activation of automatic associations
(Lueke and Gibson, 2015). e reason for this might bethe choice of
the implicit measurement paradigm (see 4.4. Limitations).
4.4. Limitations
We implemented a controlled longitudinal intervention instead of
a cross-sectional design to allow causal conclusions and interpretations
of eects. However, some limitations must beconsidered.
First, weonly considered attitudes toward vegetarian foods as one
possible way of sustainable eating behavior. As stated before, there are
many dierent types of sustainable nutrition and following a vegetarian
lifestyle is just one of them. In addition, sustainable eating behavior has
more dimensions than just food consumption. Factors like, for example,
cultivation and production of food or recycling and disposal of
packaging also must beconsidered as well in terms of sustainability (see
Geiger etal. (2018) for an integrative cube framework of sustainable
consumption behavior). Second, regarding the implementation of the
SSBC, it must benoted that the sample size of each stage was rather
small (e.g., 11in pre-decision stage, see Table3). us, discriminatory
validity is limited. Furthermore, stage aliation was determined by one
single-choice item and was therefore only based on self-report that
could bebiased by other factors such as social desirability. Another
major methodological drawback of our study is the lack of signicant
results regarding the implicit aective attitudes in our investigation. e
reason might be the choice of the implicit measurement method.
Weused an implicit aective priming paradigm as aective motives are
seen as relevant factors in environmental psychology (Steg, 2005).
Another established task could bethe Implicit Association test (IAT)
which focuses on cognitive aspects of attitudes (see Greenwald and Lai,
Winkelmair and Jansen 10.3389/fpsyg.2023.1158410
Frontiers in Psychology 13 frontiersin.org
2020). However, priming procedures generally suer from lower
reliability (e.g., Cameron et al., 2012). Another limitation of our
investigation might bethe choice of picture material in the explicit and
implicit measurement. As taste varies between people, it cannot
beassured that individual preferences did not impact aective attitudes.
Especially in the explicit rating, the participants had to indicate whether
they “like” the displayed foods regardless of sustainability aspects. As
mentioned above, the reasons for a vegetarian diet are various, and no
clear inferences can be derived as to whether attitudes toward
sustainability were measured. In addition, as we did not monitor
whether the participants were hungry or satiated during the tests, a
possible sensation of hunger or appetite could also have inuenced the
aective evaluation of the dishes. Other limiting factors underlie the
structure of our sample. Demographic analyses of the three intervention
groups revealed signicant discrepancies regarding age and attended
group sessions. Moreover, our sample included both vegetarian/vegan
and omnivorous participants. Previous research indicated that there are
attitude dierences between vegetarians/vegans and omnivores in terms
of a more positive attitude toward vegetarian products in vegetarians
compared to omnivores and a more positive attitude toward meat in
omnivores compared to vegetarians (e.g., Barnes-Holmes etal., 2010;
Siebertz etal., 2022). us, it might bemore crucial to improve the
attitudes toward vegetarian foods especially of omnivorous people.
Future studies might prot from rather omnivorous samples to
determine the impact of mindfulness interventions on the attitudes
toward vegetarian foods, as larger eects can be achieved in this
population. Last, as our explorator y analysis revealed gender dierences
in the explicit aective attitudes toward both vegetarian and meat-based
foods. is discrepancy is in line with previous research suggesting that
nutritional attitudes and eating habits might vary with gender (e.g., Love
and Sulikowski, 2018), implying that gender should be taken into
account as a factor in future studies on intervention eects on attitudes
toward foods.
4.5. Implications for research and practice
In our intervention study, there was an improvement in the
explicit aective attitudes toward vegetarian foods for all three
12 weeks long curriculums—compassion and caring-based
intervention with LKM, a rather attention-focused adapted MBSR
course, and as an active control group PMR training—despite the
group assignment. ese ndings highlight the value of implementing
mindfulness and stress-reduction trainings as potential interventions
to promote vegetarianism and, thus, a way of sustainable food
consumption. Accordingly, more courses of this form should bemade
accessible to a broad public as possible. However, implementing the
SSBC revealed social and personal norms as signicant predictors of
goal intention, thus aiming for a vegetarian diet. Future studies
should focus more on social and personal norms and values as
changes in individual inner dimensions are promising for
sustainability and possibly in particular sustainable nutrition. Last,
since our study showed no signicant results for the implicit aspects
of attitudes, researchers should consider dierent implicit
measurements to validate their results and gure out the most
appropriate method in the specic case.
Data availability statement
e datasets presented in this study can be found in online
repositories. e names of the repository/repositories and accession
number(s) can befound at: https://osf.io/x9jaq/?view_only=9a68fdb
44e6f4b1d986565492dda9202.
Ethics statement
e studies involving humans were approved by the ethics board
of the University of Regensburg (Reference number: 20-1740-101).
e studies were conducted in accordance with the local legislation
and institutional requirements. e participants provided their written
informed consent to participate in this study.
Author contributions
PJ designed the study and developed the theoretical framework. AW
conducted the implementation, organized the project, and wrote the rst
dra of the manuscript. All authors performed the statistical analyses,
edited the manuscript, read, and approved the nal submitted version.
Funding
is research was nancially supported by EDEN foundation (Im
Stierverband für die Deutsche Wissenscha; Barkhovenallee 1
45239 Essen), grand ID S0289/10048/20. ere was no involvement
in study design, collection, analysis, and interpretation of data, or
writing of the manuscript.
Acknowledgments
We want to thank Nadine Richter for providing us with the material
of the measurement of the SSBC and Jens Blechert for providing the
picture material for the explicit and implicit measurements. Nadine
Richter had no involvement in study design, collection, analysis,
interpretation of data, the writing of this article or the decision to submit
it for publication.
Conflict of interest
e authors declare that the research was conducted in the
absence of any commercial or nancial relationships that could
beconstrued as a potential conict of interest.
Publisher’s note
All claims expressed in this article are solely those of the authors
and do not necessarily represent those of their aliated organizations,
or those of the publisher, the editors and the reviewers. Any product
that may be evaluated in this article, or claim that may be made by its
manufacturer, is not guaranteed or endorsed by the publisher.
Winkelmair and Jansen 10.3389/fpsyg.2023.1158410
Frontiers in Psychology 14 frontiersin.org
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