This study aimed to (1) investigate the feasibility of three online-delivered mindfulness practices that emphasize different types of attentional focus: visceral body scan (VBS), somatosensory body scan (SBS), and external (non-body) meditation (ECM), and (2) gain insight into the potential effects of these interventions on interoceptive and other psychological outcomes.
Method
A pilot randomized controlled trial was conducted in a community-based sample recruited from social networks. It consisted of a 1-week online intervention of either VBS, SBS, or ECM. Feasibility measures included the study retention rate, adherence, mindfulness practice quality, mindfulness-related adverse effects, and acceptability. Several questionnaires on interoceptive, mindfulness, and emotional outcomes were administered before and after the intervention.
Results
A total of 48 adult individuals were enrolled. The retention rate was 66.20% and the adherence to the meditation practice was 56.53%. Acceptability and quality of the mindfulness practice were moderate, and most participants reported no adverse effects. We found some preliminary effects related to specific conditions (e.g., VBS was related to a decrease in attention to unpleasant bodily sensations), while other trends were found to be common among several conditions (e.g., VBS and SBS were associated with a preliminary decrease in the level of dampening of positive emotions).
Conclusions
Our findings suggest that improvements in feasibility are needed before this study design can be applied in larger-scale research. Hence, some refinements for the study protocol are proposed. Implications and future directions for this area of research are also discussed.
Preregistration This study was retrospectively registered in ClinicalTrials.gov on 31 January 2024 (NCT06237530).
Catherine Andreu was affiliated with the University of Valencia when the study was conducted and is currently affiliated with Universidade de Santiago de Compostela.
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Interoception refers to the processing of internal bodily cues by the central nervous system (Khalsa et al., 2018). According to Nord and Garfinkel (2022), visceral sources—such as cardiovascular, respiratory, gastrointestinal, bladder signals, and visceral pain—are universally considered interoceptive. Interoception differs from proprioception, which involves the perception of body position and movement in space. While proprioception enables coordination and balance—such as knowing where one’s limbs are without looking—interoception is more closely related to physiological self-awareness. For example, attending to and detecting interoceptive signals can involve focusing on one’s heartbeat and noticing subtle variations in its rhythm. Individuals with greater cardiac interoceptive accuracy may be more attuned to these changes. However, certain bodily sensations that are not strictly visceral—such as muscle tension, itch, or skin temperature—are more controversial, as they are considered interoceptive by some authors but also proprioceptive or exteroceptive by other researchers. Interoception is a multidimensional construct that includes various domains. These dimensions include performance in tasks related to attention and detection of interoceptive signals (referred to as interoceptive accuracy), and the assessment of an individual’s perception and evaluations of these signals (referred to as interoceptive sensibility) (Garfinkel et al., 2015).
Atypical interoception has been considered a risk factor for psychopathology (Brewer et al., 2021; Paulus et al., 2019), with evidence of alterations in interoceptive processing in several clinical and subclinical populations. For example, individuals with eating disorders often struggle to accurately perceive hunger and satiety cues, contributing to maladaptive eating behaviors (Jenkinson et al., 2018). Similarly, those with anxiety disorders may misinterpret normal physiological sensations—such as an increased heart rate—as signs of imminent danger, exacerbating their symptoms (Brewer et al., 2021). Moreover, deficits in interoceptive accuracy and/or sensibility have been observed in individuals with alexithymia (Brewer et al., 2016), poor emotion regulation skills (Füstös et al., 2013; Zamariola et al., 2019), and depression (Eggart et al., 2019; Harshaw, 2015).
Given the growing interest in interoceptive disturbances as a key mechanism involved in a wide variety of clinical conditions, several interventions have been proposed to improve interoceptive processing (i.e., to increase interoceptive accuracy or sensibility). These approaches include—but are not limited to—neuromodulation (e.g., vagus nerve stimulation), pharmacological interventions (e.g., adrenergic blockade such as propranolol), and psychological interventions, such as biofeedback and mindfulness-based interventions (Nord & Garfinkel, 2022; Weng et al., 2021).
Regarding psychological interventions, on the one hand, biofeedback consists of providing visual, acoustic, or tactile stimuli as feedback about one’s own physiological activity (Gartha, 1976), such as the heartbeat. Previous research shows that cardiac biofeedback can increase interoceptive accuracy after a single session compared to control conditions (Meyerholz et al., 2019; Schillings et al., 2022). However, this effect was not greater or even maintained when cardiac feedback was applied once a week for 3 weeks (Schillings et al., 2022). Furthermore, interoceptive sensibility (measured with confidence ratings about one’s cardiac interoceptive accuracy) was not significantly changed by cardiac biofeedback (Schillings et al., 2022).
On the other hand, mindfulness-based interventions refer to a wide variety of therapeutic techniques that use a mindfulness approach, which involves paying attention to moment-to-moment thoughts, feelings, and sensations in a nonjudgmental and accepting way (Kabat-Zinn, 2015). The use of mindfulness-based interventions to promote mental health in non-clinical settings is an increasingly common practice (Clarke et al., 2015), and a notable body of research has addressed their efficacy through randomized controlled trials (RCTs) (Galante et al., 2021). Meta-analytic studies have found that mindfulness-based approaches contribute to greater psychological well-being in a wide variety of clinical and non-clinical populations (Querstret et al., 2020; Zhang et al., 2021). However, the mechanisms of mindfulness need to be further elucidated, especially those pertaining to body awareness (Burzler et al., 2019), such as interoception.
Within the mindfulness approach, body scan is a meditative practice that involves voluntarily shifting attention to different parts of the body and noticing, without judgment, the physical sensations that occur there (Farb et al., 2015; Lima-Araujo et al., 2022). Therefore, body scan practice is considered a relevant technique for training interoceptive processing (e.g., Parkin et al., 2014; Weng et al., 2021). In particular, body scan seems to be a plausible way to promote the healthy (and mindful) attentional style of interoceptive sensibility described by Mehling (2016), as opposed to the anxiety-driven attentional style. The former involves an open, accepting, and non-reactive awareness of bodily sensations, while the latter is characterized by hypervigilance, catastrophizing, and misinterpretation of internal bodily cues, such as perceiving normal cardiac fluctuations as signs of impending danger. However, the evidence regarding the effects of the body scan on interoception is unclear. For instance, Bornemann et al. (2015) found that daily practice of body scan and breath meditation for 3 months was significantly associated with increased scores on five out of eight dimensions of the Multidimensional Assessment of Interoceptive Awareness (Mehling et al., 2012), a widely used self-reported questionnaire of interoceptive sensibility. In contrast, other studies found no significant benefits of the body scan. For instance, Karanassios et al. (2021) did not find any increase in interoceptive abilities (i.e., interoceptive accuracy or sensibility as measured with confidence ratings on one’s own accuracy) or reductions in severity of depressive symptoms after the body scan greater than those obtained with other active conditions, such as cognitive-behavioral therapy. Therefore, further research is needed to elucidate the effects of body scan practice on interoceptive processes. Beyond the effects of the body scan on interoception, effects on other psychological outcomes (for which interoception is known to be relevant) are also inconclusive. For instance, a recent meta-analysis on the effects of body scan meditation found no evidence of a beneficial effect on improving clinical symptoms such as depression compared to either active or passive control conditions (Gan et al., 2022).
At this point, it should be noted that body scan involves tracking bodily sensations in general (not just interoceptive signals); that is, it includes both interoceptive sensations (e.g., breathing) and somatosensory sensations, such as tactile (e.g., itching) and proprioceptive (e.g., muscle tension) (Dreeben et al., 2013; Kabat-Zinn, 2018). This variety of signal types that are the focus of attention in the body scan might explain why research did not provide consistent results. Additionally, even if effects are observed, the mechanisms responsible for them cannot be determined due to this heterogeneity in the target of the attentional focus (i.e., interoceptive and somatosensory sensations).
In sum, given the growing interest in interoceptive disturbances as a key transdiagnostic mechanism, several interventions have been proposed to improve interoceptive processing. Among these, body scan meditation is particularly relevant due to its mindfulness-based framework. However, its effects on interoceptive measures remain unclear, and its benefits for broader psychological outcomes, such as reductions in depressive symptoms, have not been consistently observed. One possible explanation is that body scan does not exclusively target interoceptive (visceral) signals. Instead, it involves a broader attentional focus, incorporating both somatosensory (e.g., tactile) and interoceptive (i.e., visceral) signals. This lack of specificity in attentional focus may dilute its effectiveness as a targeted interoceptive intervention.
In recent years, online formats have proven effective for delivering interventions while increasing accessibility and reducing costs and time (de Bruin et al., 2020; Jayawardene et al., 2017). They offer unique opportunities to reach diverse populations and facilitate cross-cultural investigations. In this sense, the inclusion of alternative language options in clinical trials has been recommended (Bodicoat et al., 2021). Novel mindfulness-based protocols can therefore be delivered online to examine both feasibility and the specific impact of targeting different bodily systems. Key feasibility indicators include recruitment (i.e., identification of eligible participants in a given time period), retention rate (i.e., percentage of enrolled participants who completed all the study procedures), adherence (i.e., percentage of daily meditation sessions completed), quality of mindfulness practice (i.e., persistent, non-striving focus on present-moment awareness during mindfulness meditation, with an open and accepting approach), safety (i.e., absence of meditation-related adverse effects), and acceptability (i.e., participant’s satisfaction with the study procedures). By systematically directing attention toward different bodily sensations, it would be possible to clarify whether focusing specifically on interoceptive (visceral) signals enhances interoceptive processing more effectively than the traditional, mixed-focus body scan. Ultimately, this could have important implications for conditions in which interoceptive processes play a crucial role.
The aims of this pilot RCT were (1) to assess the feasibility of implementing a novel meditation protocol focused on differentiating attentional targets (i.e., visceral, somatosensory, and external signals) and (2) to preliminarily explore their distinct psychological effects. An online format was employed, with all materials provided in Spanish and English. Feasibility was evaluated based on the following criteria: retention rate ≥ 80%, completion rate ≥ 70%, medium-to-high mindfulness practice quality, low incidence of adverse effects, and participant satisfaction, based on previous pilot studies (Eisele et al., 2023; Frommelt et al., 2023). The outcomes assessed included interoceptive sensibility, body self-awareness, mindfulness, alexithymia, emotion regulation, and depressive symptomatology. Three meditation conditions were designed: the visceral body scan (VBS), emphasizing internal organ sensations; the somatosensory body scan (SBS), focused on skin and musculoskeletal sensations; and the external control meditation (ECM), directing attention to the environment. We hypothesized general improvements across all conditions, given their mindfulness-based nature (Hill & Updegraff, 2012; Querstret et al., 2020), with greater increases in interoceptive sensibility for VBS compared to SBS and ECM, and enhanced body self-awareness for both VBS and SBS relative to ECM.
Method
Participants
The eligibility criteria included (1) age over 18 years, (2) being Spanish or English speakers, (3) ability to use a computer or smartphone, and (4) having daily access to a computer or smartphone with an Internet connection. Exclusion criteria were (1) being diagnosed with a severe psychiatric disorder (e.g., substance abuse, eating disorder, psychotic disorder); (2) severe visual or auditory difficulties that cannot be corrected with glasses or auditory aids; (3) having a medical condition that prevents participation in this study; (4) changes in psychotropic medication during the study; (5) having been exposed to any extremely traumatic event that is being re-experienced or interfering during the last month; (6) regular meditation practice in the current moment; and (7) body image–related difficulties, indicated by scores above 3 on the Body Image Shame Scale (BISS) (Duarte et al., 2015). The decision to exclude participants with high levels of body shame aimed to minimize the potential risk of distress. Body shame, which is a common risk and maintenance factor in eating disorders, is closely associated with self-criticism and self-rejection (Gilbert & Procter, 2006; Kelly et al., 2013). Given that two of the three conditions (i.e., VBS and SBS) require focused attention on one’s body, which is known to be associated with increased self-awareness (Palmer & Tsakiris, 2018), they could be distressing for individuals with high levels of body shame. While prior research has shown positive effects of mindfulness-based interventions in individuals with body image–related issues, these programs adapted the body-focused practices (e.g., body scan) to incorporate a compassionate perspective, which may help to mitigate potential risks (Albertson et al., 2015; Kristeller et al., 2014; Toole & Craighead, 2016).
Following sample size recommendations for pilot feasibility studies (Whitehead et al., 2016), we aimed to recruit 15 participants per treatment arm.
Procedure
The study design was a mixed design with a between-subjects factor (condition with three levels: visceral body scan -VBS-, somatosensory body scan -SBS-, external control meditation -ECM-) and a within-subjects factor (time, with two levels: pre- vs. post-training). A 1:1:1 randomization ratio was used. Random allocation was performed automatically using an R script (see Online Resource 1). The code for the random allocation sequence was generated by the first author, who also ran the code to assign participants to the experimental conditions.
After completing the pre-assessment, participants were involved in their corresponding meditation training for 7 days. On the eighth day, they were asked to complete the post-assessment. Participants provided voluntary informed consent before enrolling in the study. Participants received no financial incentives but were thanked and informed of their results. This study follows the extension of the CONSORT statement to pilot and feasibility trials (Eldridge et al., 2016) (see Online Resource 8).
All components of the study were conducted in an online environment. Participants were recruited through media announcements posted on the social media profiles of our research group and team members (e.g., Instagram, Facebook, LinkedIn). In addition, local collaborators were asked to disseminate study announcements on their social media accounts. Given the online nature of the recruitment, potential participants could come from various countries. To enhance inclusivity and facilitate future cross-cultural investigations of the meditation practices examined, study materials were provided in both English and Spanish. The information disseminated referred to “a study to get introduced into mindfulness practice,” and all procedures were fully explained in writing. In addition, participants could ask questions via email or telephone. It took 4 weeks to reach the target sample size, between 26 July and 21 August 2023.
As a first step, interested individuals completed a brief screening survey using the “Qualtrics” platform. Participants who met the eligibility criteria were emailed the link to the baseline survey and a brief outline of the study procedures (Fig. 1). After completing the baseline survey, they were emailed a 3-min psychoeducational video on mindfulness (Online Resource 2) and the instructions for installing and configuring the “m-Path” app, through which the intervention was delivered. After completing the intervention, they were emailed a link to the post-assessment survey. Upon completion, participants were emailed a report with some of their results in the measures administered and a thank you note. Participants were unaware that the study was testing different online interventions, or that they were assigned to a specific experimental condition. Emails containing assessments, instructions, psychoeducation, and individual outcome reports were identical for all the participants. Participants were sent reminders in the following cases: (1) if they did not complete the pre-intervention survey within 2 days of receiving it; (2) if they did not download the “m-Path” app within 2 days of receiving the instructions for it; and (3) if they did not complete the post-intervention survey within 2 days of receiving it.
After the pilot study began, two changes were made to the methods to reduce the risk of dropout: (1) a daily morning message was sent during the intervention as a reminder to perform the meditation practice via m-Path, and (2) an email was sent on the third day of meditation practice to remind participants of the psychoeducational content and that they could contact us if they had any difficulties or doubts about their participation in the study.
The psychoeducational materials and the three experimental conditions (VBS, SBS, and ECM) were created by two mindfulness instructors with expertise in delivering mindfulness-based treatments. The three conditions consisted of daily formal meditation practices delivered via 10-min recorded audio instruction using the “m-Path” app for 1 week. Participants were asked to find a quiet place to complete the daily 10-min practice at any time during the day. The scripts and audio recordings for all the conditions are provided in the Online Resource 2. The decision to use a 10-min meditation was informed by previous research on online mindfulness interventions. Specifically, several studies showed that daily 10-min meditation practices can improve several mental health outcomes—including affect, mindfulness, anxiety, and depression (Bailey et al., 2018; Cavanagh et al., 2013). In fact, Strohmaier et al. (2021) found that shorter meditations were more effective at increasing mindfulness and reducing stress than longer practices. Regarding the 1-week intervention duration, this decision was made based on the exploratory, feasibility-focused nature of the pilot study. Although previous research indicates that brief mindfulness programs (i.e., less than 2 weeks) yield positive, albeit small, effects on mental health outcomes among individuals without meditation experience (Schumer et al., 2018), it is also known that the benefits of mindfulness practice increase with more consistent practice (Bailey et al., 2018). Given that our primary aim was to assess the feasibility of the intervention rather than its efficacy, we opted not to extend the intervention duration further until its feasibility was confirmed.
The VBS consisted of a mindfulness exercise designed to bring awareness to visceral sensations in the cardiac, respiratory, gastrointestinal, and urinary systems. These physiological systems were chosen because most of the paradigms developed in the literature to assess interoception focus on them (Khalsa et al., 2018) and they are widely recognized in the literature as interoceptive senses (Nord & Garfinkel, 2022).
The SBS consisted of a mindfulness exercise designed to bring awareness to tactile (e.g., itching) and musculoskeletal (e.g., tension) sensations in different parts of the body, namely, the head and neck, back, arms, and legs. Body scan exercises typically focus on these types of bodily cues (in addition to breathing) (Williams, 2010).
The ECM consisted of a mindfulness exercise designed to bring awareness to external stimuli, including sounds and visual properties of the environment.
Measures
Socio-demographic Characteristics and Eligibility Information
We collected information on gender, age, education level, occupation, country of birth, country of residence, height, weight, and physical exercise (i.e., sports, dance, or circus arts).
Pre- and Post-intervention Measures
The following outcomes were assessed: interoceptive sensibility, body self-awareness, mindfulness, alexithymia, emotion regulation, and depressive symptomatology. The selection of these outcomes was based on their direct relevance to the objectives. In particular, interoceptive sensibility and body self-awareness were prioritized given their close link to the theoretical rationale underlying the body-focused meditation conditions (i.e., VBS and SBS). Recognizing the multifaceted and heterogeneous nature of interoception, a battery of complementary measures was used to ensure comprehensive assessment (see descriptions below). In addition, a mindfulness questionnaire was included as a core component common to all conditions, and measures of alexithymia and emotion regulation were added due to their relevance on mindfulness in general and body scan in particular (Bornemann & Singer, 2017; Hill & Updegraff, 2012; Shireen et al., 2024). Finally, depressive symptomatology was assessed, as it is one of the clinical symptoms most present in systematic reviews and meta-analyses in this field (Gan et al., 2022; Querstret et al., 2020; Zhang et al., 2021). Below is a detailed description of each measure.
Interoceptive Sensibility
Previous research suggests that interoceptive sensibility as measured by different instruments does not overlap; that is, different questionnaires assess different constructs (Desmedt et al., 2022; Vig et al., 2022). Since one of the main components of the interoceptive questionnaires is the processing of internal bodily sensations in a broad sense, and attention to internal (visceral) bodily sensations is a crucial aspect of this study, we decided to include several measures to capture this broad construct more accurately. The Multidimensional Assessment of Interoceptive Awareness-2 (MAIA-2) (Desdentado et al., 2023; Mehling et al., 2018) was administered, which consists of 37 items rated on a 6-point Likert scale, ranging from 0 (never) to 5 (always). Based on the work of Ferentzi et al. (2021), we computed an overall score that included all the dimensions of this questionnaire except for the Not-Distracting and Not-Worrying subscales, which were calculated separately. Higher scores reflect higher levels of interoceptive sensibility. The MAIA-2 captures a general mindful and healthy interoceptive attentional style, not so much focused on the attention paid to bodily sensations per se as other instruments do, but on the interpretation, valuation, or use made of them. In this study, the internal consistency of the MAIA-2 total score (αpre = 0.94, αpost = 0.94, ⍵pre = 0.96, ⍵post = 0.96), as well as the Not-Distracting (αpre = 0.71, αpost = 0.65, ⍵pre = 0.89, ⍵post = 0.90) and Not-Worrying (αpre = 0.83, αpost = 0.54, ⍵pre = 0.84, ⍵post = 0.58) subscales, was adequate, except for the post-training Not-Worrying subscale.
In addition, the State Interoceptive Awareness Questionnaire (SIAQ) (Pollatos et al., 2016) was used to assess interoceptive sensations (e.g., “My heart beats calmly and steadily”) in the following modalities: heartbeat, breathing, trembling, temperature/sweating, and gastrointestinal sensations. It includes 18 items rated on a 5-point Likert scale, ranging from 1 (not at all) to 5 (very strongly). Higher scores indicate higher levels of self-reported perception of the bodily signals evaluated. As there was no Spanish validation of this instrument, the items were translated by the authors. Unlike the MAIA-2, the SIAQ assesses the extent to which certain visceral sensations are the object of attention, regardless of how they are interpreted or valued or of beliefs about their interoceptive ability. The internal consistency for the SIAQ was adequate (αpre = 0.85, αpost = 0.84, ⍵pre = 0.90, ⍵post = 0.88).
Finally, the Interoceptive Sensitivity and Attention Questionnaire (ISAQ) (Bogaerts et al., 2022) was also administered. It includes 17 items rated on a 5-point Likert scale, ranging from 1 (strongly disagree) to 5 (strongly agree). The ISAQ includes the following dimensions: sensitivity to neutral bodily changes, attention to unpleasant bodily sensations, and difficulty disengaging from unpleasant bodily sensations. The ISAQ was conceptualized as the individual’s belief in their interoceptive ability and the degree to which one feels engaged by interoceptive signals. The internal consistency for the sensitivity to neutral sensations (αpre = 0.76, αpost = 0.78, ⍵pre = 0.83, ⍵post = 0.86) and attention to unpleasant bodily sensations (αpre = 0.71, αpost = 0.81, ⍵pre = 0.44, ⍵post = 0.16) was acceptable according to at least one of the two coefficients. In contrast, the internal consistency for difficulty disengaging from unpleasant bodily sensations was consistently poor (αpre = 0.28, αpost = 0.18, ⍵pre = 0.46, ⍵post = 0.46), similar to previous research (Bogaerts et al., 2022).
Bodily Self-awareness
It was operationalized as the sense of selflessness, defined as an allocentric (vs. egocentric) frame of reference characterized by broad feelings of unity and interdependence with people and things in the environment beyond the self, which is commonly fostered by mindfulness practice (Hanley et al., 2020). In this study, we used the Perceived Body Boundaries Scale (PBBS) (Dambrun, 2016) to measure the salience of perceived body boundaries and the Spatial Frame of Reference Continuum (SFoRC) (Hanley & Garland, 2019) to measure the extent to which the area within the field of awareness experienced as self-constituent extends beyond the physical body (allocentric vs. egocentric frame of reference).
The PBBS is a visual analog scale (VAS) that depicts seven human bodies, ranging from almost imperceptible at the left pole (labeled “my body boundaries are almost imperceptible”) to extremely salient at the right pole (labeled “my body boundaries are extremely salient”). Scores can range from 0 to 15.50, with higher scores indicating greater salience in perceiving body boundaries.
The SFoRC is a VAS depicting five concentric circles surrounding the outline of a human figure, and individuals are asked to indicate how far they feel that their self extends beyond their physical body. Scores range from 1 to 6, with higher scores reflecting a more allocentric (vs. egocentric) frame of reference.
Mindfulness
We used the short form of the Five Facet Mindfulness Questionnaire (FFMQ-SF) (Asensio-Martínez et al., 2019; Baer et al., 2012). It is a 15-item instrument that measures the tendency to be mindful in daily life and has been successfully used to measure weekly changes. Items are rated on a 5-point Likert scale, from 1 (never or very rarely true) to 5 (very often or always true). It includes the following dimensions: observing, describing, acting with awareness, non-judging internal experience, and non-reactivity to internal experience. Higher scores indicated higher levels of the corresponding dimension. The internal consistency for the FFMQ-SF subscales was consistently acceptable, with α ranging from 0.72 to 0.92 and ⍵ ranging from 0.79 to 0.95.
Alexithymia
The Perth Alexithymia Questionnaire-Short Form (PAQ-S) (Becerra et al., 2021; Preece et al., 2023) is a 6-item measure that provides an overall index of alexithymia. Items are answered on a 7-point Likert scale, ranging from 1 (strongly disagree) to 7 (strongly agree). Higher scores indicate higher levels of alexithymia. The internal consistency for the PAQ-S was adequate (αpre = 0.88, αpost = 0.79, ⍵pre = 0.95, ⍵post = 0.91).
Emotion Regulation
We used the short-form version of the Difficulties in Emotion Regulation Scale (DERS-SF) (Kaufman et al., 2016) and the Responses to Positive Affect Questionnaire (RPA) (Feldman et al., 2008).
The DERS-SF is an 18-item questionnaire that measures the degree of difficulty in regulating emotions. Items are rated on a 5-point Likert scale, ranging from 1 (almost never) to 5 (almost always). It includes the following dimensions: (1) lack of emotional awareness of one’s own emotions; (2) self-reported difficulty in completing tasks and concentrating in the presence of negative emotions; (3) limited access to regulatory strategies that the individual perceives as effective; (4) nonacceptance of negative emotional states; (5) self-reported difficulty in controlling one’s behavior in the presence of negative emotional states; and (6) lack of emotional clarity, i.e., limited knowledge and clarity about one’s emotional states. However, as suggested by the bifactor analysis conducted by Moreira et al. (2022), a total score without the items from the lack of emotional awareness subscale was calculated, with higher scores indicating higher difficulties in regulating emotions. The internal consistency for the DERS-SF total was adequate (αpre = 0.90, αpost = 0.92, ⍵pre = 0.94, ⍵post = 0.94). The internal consistency for the DERS-SF awareness subscale was as follows: αpre = 0.72, αpost = 0.65, ⍵pre = 0.76, ⍵post = 0.75.
The Responses to Positive Affect Questionnaire (RPA) (Feldman et al., 2008; Hidalgo-García et al., 2019) is a 16-item questionnaire that measures responses to positive moods, including dampening (i.e., thoughts that are likely to dampen positive emotional states), self-focused positive rumination (i.e., rumination on aspects of the self and the pursuit of goals relevant to the self), and emotion-focused positive rumination (i.e., rumination on positive mood). Items are rated on a 4-point Likert scale, ranging from 1 (almost never) to 4 (almost always), with higher scores reflecting greater use of such strategy. The internal consistency for the RPA subscales was questionable according to α, which ranged from 0.46 to 0.66. However, it was acceptable according to ⍵, which ranged from 0.72 to 0.90.
Depressive Symptomatology
We used the Patient Health Questionnaire-9 (PHQ-9) (Kroenke et al., 2001), which is rated on a 4-point Likert scale, ranging from 0 (never) to 4 (almost every day). Higher scores indicate greater severity. The internal consistency for the PHQ-9 was adequate (αpre = 0.82, αpost = 0.88, ⍵pre = 0.91, ⍵post = 0.93).
The trait measures (i.e., MAIA-2, ISAQ, FFMQ-SF, PAQ-S, DERS-SF, and RPA) were adapted in the post-assessment by referring to “the last week” in the instructions. The instruments that originally referred to “the last two weeks” (i.e., PHQ-9) or to “the present moment” (i.e., SIAQ) were adapted by referring to “the last week” in both the pre- and post-assessments. The pre- and post-intervention surveys lasted approximately 20–30 min.
Final Measures
Meditation-Related Adverse Effects
The items of the Meditation-Related Adverse Effect Scale – Mindfulness-Based Program (Britton et al., 2018) were administered to assess the occurrence of specific adverse effects (e.g., “anxiety”) in their dichotomous form (yes/no questions), following the work of Goldberg et al. (2022). In addition, the items developed by Goldberg et al. (2022), which assess the frequency of “challenging, difficult, or distressing experiences” as a result of meditation, the impairment caused by such experiences, and the duration of this impairment, were included. In addition, another item measured the extent to which participants felt glad to have practiced meditation (considering the adverse effects) rated on a 6-point Likert scale, ranging from 1 (strongly disagree) to 6 (strongly agree). Participants were also asked to report any other symptoms as a result of meditation.
Acceptability
It was assessed using the Treatment Satisfaction Scale (adapted from Borkovec and Nau (1972) by Tur et al., 2022), which includes the following items rated from 0 (not at all) to 10 (very much): (1) “How logical did this intervention seem to you?”; (2) “How much do you think the intervention has been useful to you?”; (3) “How much would you recommend this intervention to a friend?”; (4) “How much do you think this intervention has been aversive (unpleasant, annoying) for you?”; and (5) “To what extent do you think you will use the strategy practiced here in the future?” Moreover, participants completed the Patient Global Impression of Change (PGIC) scale by Guy (1976) by rating their perception of overall change during the study on a 7-point scale (very much improved; improved; minimally improved; no change; minimally worse; worse; very much worse).
Mindfulness Practice Quality
It was assessed in two ways: (1) after the entire training (i.e., in the post-assessment survey) with the Practice Quality-Mindfulness (PQ-M) (Del Re et al., 2012), which consists of 6 items rated on a VAS ranging from 0 to 100, with higher scores reflecting a higher level of practice quality, and (2) a single-item PQ-M (“How would you rate the overall quality of your meditation practice today?”) administered immediately after the daily practice (Goldberg et al., 2020). This measure was responded to on a 10-point Likert scale, with higher scores reflecting higher levels of practice quality. In this study, the internal consistency of the 6-item PQ-M was adequate based on McDonald’s omega coefficient (α = 0.56, ⍵ = 0.88).
Qualitative Data
Finally, participants were asked for feedback through the following open-ended questions at the end of the post-intervention survey on the Qualtrics platform: (1) “Do you think that participating in this study has helped you learn something or become aware of something? If so, what did you learn?”; (2) “Do you think that doing the meditation practice has helped you improve anything? If so, what benefits have you noticed?”; (3) “Does this practice make sense to you, and why?”; (4) “Please describe the sensations, thoughts and/or feelings you have had while doing the meditation practice”; (5) “What difficulties have you found when doing the meditation practice?”; (6) “What did you like most about the meditation practice? And what did you like the least?”; and (7) “What do you think is the objective or hypothesis of the study?”.
Adherence
In this study, adherence was assessed by the percentage of meditation practices performed. The “m-Path” app allowed for verification of the playback time and duration of the audio recording. These data were used to calculate the number of days of meditation practice for each participant.
Data Analyses
Data were managed and analyzed using R 4.2.2 (R Core Team, 2022) and RStudio 2023.06.0 + 421 (Posit team, 2023). Descriptive statistics were used to report feasibility and acceptability, as well as the outcome measure data. Descriptive statistics were reported as means and standard deviations (SD) for continuous data, whereas absolute frequencies and relative frequencies (percentages) were reported for categorical data. Narrative descriptions were used to report qualitative data from participants’ feedback.
Given that pilot studies are considered underpowered and unrepresentative, the hypothesis-testing approach regarding the effects of the experimental conditions on outcome variables is not appropriate (Eldridge et al., 2016). Therefore, we focused on a descriptive approach. Two-way ANOVAs were computed using the “rstatix” package (Kassambara, 2023) to preliminarily explore potential trends related to the experimental conditions. The ANOVAs included a between-subjects factor (VBS, SBS, ECM) and a within-subjects factor (pre, post). ANCOVAs controlling for adherence were not performed, as the assumptions for this analysis (i.e., a moderate and consistent linear relationship between adherence and the outcomes among conditions) were not met (see Table S1, Online Resource 3). F statistics and size effects (partial eta-squared, ηp2) were reported, but statistical significance based on the p-value was not considered. ηp2 values of 0.010, 0.060, and 0.140 indicate small, medium, and large effects, respectively (Cohen, 1969). We also reported the 95% confidence intervals, although it should be noted that they reflect a large degree of uncertainty for small sample sizes (i.e., they are very wide). Thus, they should not be used as a tool for hypothesis testing in the context of pilot studies due to statistical underpower (Eldridge et al., 2016). Finally, for those variables with interaction effects that reached at least a medium size, we also performed one-way ANOVAs on the post-training scores. Three decimal points were taken into account for p-values and size effects for precision.
Reliability consistency was calculated using the “psych” package (Revelle, 2022). Specifically, Cronbach’s alpha (α) and McDonald’s omega (⍵) coefficients were calculated for all measures.
Results
Recruitment and Retention Rates
A total of 117 participants were screened for eligibility. Of these potential participants, 46 were excluded. Specifically, 23 (19.67%) did not meet the inclusion/exclusion criteria and 23 (19.67%) did not complete the pre-intervention assessment. Of the 71 participants who were randomized, 13 did not receive the allocated intervention (they did not download the app or did not engage with any meditation practice), and were therefore considered to have dropped out before starting. The remaining 58 participants started the intervention. Of these, 47 completed at least some meditation practices and the post-intervention survey and were included in the final analyses (VBS, 19; SBS, 13; ECM, 15). Therefore, the final analyzed sample consisted of 47 participants (VBS, 19; SBS, 13; ECM, 15), corresponding to a retention rate of 66.20% (VBS, 73.08%; SBS, 65%; ECM, 60%). Therefore, 40.17% of those initially interested in the study completed their participation. Figure 2 displays the CONSORT flow chart. We found no clues that could have predicted dropping out. For instance, there were no differences in PHQ-9 scores according to a Welch t-test (t (36.80) = 1.05, Cohen’s d = 0.29, 90% CI = [− 0.21, 0.79]).
Fig. 2
Participant flow chart describing recruitment and retention of participants. Note. VBS, visceral body scan; SBS, somatic body scan; ECM, external control meditation
The study included 47 participants aged between 20 and 67, M = 39.89 (SD = 13.42. Most participants were self-identified as female (78.72%) and chose to complete the study in Spanish (93.62%). In addition, most participants reported having some level of university studies (80.85%), being employed (74.47%), being born in Spain (78.72%), and living in Spain (87.23%). Those with a different country of origin or residence were mainly from Spanish-speaking Latin American countries (e.g., Colombia, Uruguay, Venezuela, Argentina). However, a few resided in other countries, including the United States, France, Switzerland, India, and Australia. The characteristics and socio-demographic data of the participants included in data analyses are presented in Table 1.
Table 1
Characteristics and demographic information of participants in the VBS, SBS, and ECM groups
VBS (n = 19)
SBS (n = 13)
ECM (n = 15)
Age (years), M (SD)
41.53 (12.13)
41.85 (15.10)
36.13 (13.61)
Gender (women), n (%)
17 (89.47%)
10 (76.92%)
11 (68.75%)
Education, n (%)
None
0 (0%)
0 (0%)
0 (0%)
Primary school
0 (0%)
1 (7.69%)
1 (6.67%)
Secondary school
2 (10.53%)
0 (0%)
0 (0%)
Baccalaureate/vocational training
2 (10.53%)
3 (23.08%)
0 (0%)
University bachelor’s degree
5 (26.32%)
5 (38.46%)
7 (46.67%)
University master’s degree
7 (36.84%)
3 (23.08%)
4 (26.67%)
PhD
3 (15.79%)
1 (7.69%)
3 (20%)
Occupational status, n (%)
Student
1 (5.26%)
1 (7.69%)
2 (13.33%)
Employed
16 (84.21%)
10 (76.92%)
9 (60%)
Housework
1 (5.26%)
0 (0%)
1 (6.67%)
Unemployed
1 (5.26%)
1 (7.69%)
1 (6.67%)
Retired
0 (0%)
0 (0%)
1 (6.67%)
Permanent incapacity for work
0 (0%)
0 (0%)
1 (6.67%)
Time off work
0 (0%)
1 (7.69%)
0 (0%)
Country of origin (Spain), n (%)
15 (78.95%)
11 (84.62%)
11 (73.33%)
Country of residence (Spain), n (%)
17 (89.47%)
12 (92.31%)
12 (80%)
Body mass index, M (SD)
23.53 (3.71)
22.93 (4.16)
22.75 (2.62)
VBS visceral body scan, SBS somatosensory body scan, ECM, external control meditation
Feasibility
Study Adherence
Regarding the meditation practice, we found seven unfinished meditation sessions (in different participants). Specifically, they were played for a few seconds (e.g., 10 s), so we counted them as missing. The percentage of meditation sessions performed was 56.53% for the total sample. Specifically, the percentage of meditation sessions performed per group was as follows: 53.38% for the VBS group, 60.44% for the SBS group, and 57.14% for the ECM group. Table S3 (Online Resource 4) shows the frequency and percentage of session completion among conditions. Figure S1 (Online Resource 5) shows the percentage of meditation practice performed in all sessions for participants in the VBS, SBS, and ECM conditions.
Mindfulness Practice Quality
Overall, the single-item PQ-M (ranging from 1 to 10) had M = 7.21 (SD = 1.88) in the total sample. Specifically, the mean scores on the single-item PQ-M per groups were as follows: 7.11 (SD = 1.56) for the VBS group, 7.69 (SD = 1.69) for the SBS group, and 6.88 (SD = 2.30) for the ECM group. Regarding the mean scores on the 6-item PQ-M (ranging from 0 to 100) at the post-intervention assessment, it was 63.34 (SD = 17.91) in the total sample. Specifically, the mean scores on the 6-item PQ-M per groups were as follows: 61.11 (SD = 18.10) for the VBS group, 63.19 (SD = 17.34) for the SBS group, and 66.28 (SD = 18.95) for the ECM group. Figure S2 (Online Resource 6) shows the box plots by group for the single-item PQ-M and for the 6-item PQ-M.
Safety
Overall, most participants reported no meditation-related adverse effects in the three conditions. However, there were a few exceptions (Table 2). Specifically, a few participants reported anxiety and emotional sensitivity in the VBS group, as well as emotional sensitivity in the SBS group, and anxiety, traumatic re-experiencing, emotional sensitivity, difficulty sleeping, headaches and/or body pain, and feeling disconnected from everything in the ECM group. However, the frequency of meditation-related adverse effects and their associated impairment were low. No other negative effects of meditation practice were reported. Overall, even considering the adverse effects that they might have experienced, the total sample felt glad to have practiced meditation, M = 4.91 (SD = 1.36) (ranging from 1 to 6). On average, in this item, the VBS group had M = 4.47 (SD = 1.58), the SBS had M = 5.23 (SD = 1.17), and the ECM group had M = 5.2 (SD = 1.15). A one-way ANOVA revealed no substantial differences among conditions (F (2,44) = 1.72, ηp2 = 0.073), although the mean score was slightly lower in the VBS than in the SBS and ECM groups. Therefore, the study procedures appear to be safe.
Table 2
Meditation-related adverse effects in the VBS, SBS, and ECM groups, and in the total sample
Variable
VBS
(n = 19)
SBS
(n = 13)
ECM
(n = 15)
Total sample
(n = 47)
Frequency of specific adverse effects (yes/no), n (%)
Trouble thinking clearly
0
0
0
0
Anxiety
3 (15.79%)
0
1 (6.67%)
4 (8.51%)
Traumatic re-experiencing
0
0
2 (13.33%)
2 (4.26%)
Emotional sensitivity
2 (10.53%)
1 (7.69%)
1 (6.67%)
4 (8.51%)
Trouble enjoying things
0
0
0
0
Feeling distant or cut off from others
0
0
0
0
Difficulty sleeping
0
0
1 (6.67%)
1 (2.13%)
Experiencing headaches and/or body pain
0
0
1 (6.67%)
0
Sensitive hearing
0
0
0
0
Feeling disconnected from everything
0
0
1 (6.67%)
1 (2.13%)
None of the above
15 (78.95%)
12 (92.31%)
12 (92.31%)
39 (82.98%)
Frequency of adverse effects, n (%)
Never
8 (42.11%)
11 (84.62%)
11 (73.33%)
30 (63.83%)
Rarely
2 (10.53%)
2 (15.38%)
3 (20%)
7 (14.89%)
Occasionally
8 (42.11%)
0 (0%)
0 (0%)
8 (17.02%)
Regularly
0 (0%)
0 (0%)
0 (0%)
0 (0%)
Frequently
0 (0%)
0 (0%)
1 (6.67%)
1 (2.13%)
Frequency impairment, n (%)
Never
12 (63.16%)
13 (100%)
14 (93.33%)
39 (82.98%)
Rarely
1 (5.26%)
0 (0%)
0 (0%)
1 (2.13%)
Occasionally
4 (21.05%)
0 (0%)
0 (0%)
4 (8.51%)
Regularly
0 (0%)
0 (0%)
1 (6.67%)
0 (0%)
Frequently
1 (5.26%)
0 (0%)
0 (0%)
1 (2.13%)
Duration impairment, n (%)
1 day or less
5 (26.32%)
2 (15.38%)
0 (0%)
7 (14.89%)
A few days a week
2 (10.53%)
0 (0%)
1 (6.67%)
3 (6.38%)
The whole week
0 (0%)
0 (0%)
0 (0%)
0 (0%)
Othersa
1 (5.26%)
0 (0%)
0 (0%)
1 (2.13%)
I have not felt any dysfunction
11 (57.89%)
11 (84.62%)
14 (93.33%)
36 (76.6%)
aOne person reported that the duration of the impairment lasted a few minutes
Acceptability
Table 3 shows the results of acceptability for participants in the three experimental conditions and in the total sample. Scores on satisfaction items (ranging from 0 to 10) were medium-to-high in all groups. The 58.69% of the total sample perceived that practicing meditation had produced some changes for the better to a varying degree (and increases to 65.63% for those who meditated at least 3 days). However, the rest of the participants reported not having perceived any change.
Table 3
Acceptability results for participants in the VBS, SBS, and ECM groups
Variable
VBS (n = 19)
SBS (n = 13)
ECM (n = 15)
Total sample (n = 47)
Satisfaction, M (SD)
1. Meaningful
6.26 (2)
7.69 (1.84)
6.36 (1.77)
6.7 (2.46)
2. Useful
5.95 (2.53)
7.15 (1.86)
5.50 (2.11)
6.15 (2.63)
3. Would recommend it
6.63 (2.77)
7.62 (2.14)
6.79 (2.4)
6.96 (2.73)
4. Aversivea
1.26 (2.28)
0.54 (0.78)
0.86 (0.76)
0.93 (1.68)
5. Would use it in the future
5.95 (3.42)
5.92 (3.07)
5.93 (3.23)
5.93 (3.43)
Change perception, n (%)
Very much improved
2 (10.53%)
0 (0%)
1 (7.14%)
3 (6.52%)
Improved
5 (26.32%)
6 (46.15%)
5 (35.71%)
16 (34.78%)
Minimally improved
3 (15.79%)
3 (23.08%)
2 (14.29%)
8 (17.39%)
No change
9 (47.37%)
4 (30.77%)
6 (42.86%)
19 (41.30%)
Minimally worse
0 (0%)
0 (0%)
0 (0%)
0 (0%)
Worse
0 (0%)
0 (0%)
0 (0%)
0 (0%)
Very much worse
0 (0%)
0 (0%)
0 (0%)
0 (0%)
VBS visceral body scan, SBS somatosensory body scan, ECM external control meditation. The scoring range for satisfaction items was 0–10. aThe direction of the scores on the aversiveness item is opposite to the direction of the rest of the satisfaction items
Preliminary Effects of Attending to Different Cues in Meditation Practice
Results of Measures Administered Pre- and Post-intervention
Table 4 shows the means and standard deviations for the outcome measures at the pre- and post-intervention assessments for participants in the VBS, SBS, and ECM groups, the 95% confidence intervals for the mean differences between the pre- and post-intervention assessments, and the F statistics and size effects (ηp2) for the time and interaction effects.
Table 4
Descriptive statistics for the outcome measures (pre and post) for the VBS, SBS, and ECM conditions and results of ANOVAs
VBS (n = 19)
SBS (n = 13)
ECM (n = 15)
Time
Time × condition
Pre
Post
95% CI
Pre
Post
95% CI
Pre
Post
95% CI
F(1,44)
ηp2
F(2,44)
ηp2
Lower
Upper
Lower
Upper
Lower
Upper
MAIA-2 total
3.18 (0.53)
3.37 (0.66)
− 0.21
0.58
3.03 (0.9)
3.29 (0.91)
− 0.47
1.00
3.08 (1.13)
3.18 (0.89)
− 0.66
0.86
5.93
0.119
0.35
0.016
MAIA-2 not-distracting
2.42 (0.98)
2.49 (0.85)
− 0.54
0.68
2.26 (0.67)
2.6 (0.59)
− 0.17
0.86
2.01 (1.03)
2.41 (0.81)
− 0.29
1.09
3.66
0.077
0.58
0.026
MAIA-2 not-worrying
2.46 (0.93)
2.71 (0.79)
− 0.32
0.81
2.91 (0.94)
2.94 (0.90)
− 0.67
0.82
2.52 (1.04)
2.71 (0.72)
− 0.49
0.86
2.55
0.055
0.21
0.009
SIAQ
1.88 (0.69)
1.77 (0.5)
− 0.50
0.29
1.86 (0.47)
1.78 (0.42)
− 0.46
0.26
2.12 (0.57)
1.89 (0.58)
− 0.67
0.19
4.65
0.096
0.43
0.019
ISAQ neutral sensations
31.21 (6.4)
31.68 (5.69)
− 3.51
4.46
31.92 (4.15)
32 (5.2)
− 3.74
3.89
29.73 (5.06)
31.8 (4.62)
− 1.56
5.69
2.93
0.062
1.37
0.059
ISAQ unpleasant sensations
14.16 (2.34)
12.95 (3.01)
− 2.99
0.57
12.92 (3.09)
13.54 (3.5)
− 2.06
3.29
12.47 (3.96)
14 (3.4)
− 1.23
4.30
0.46
0.010
3.43
0.135
ISAQ engaging with unpleasant sensations
14.37 (2.34)
13.95 (2.48)
− 2.01
1.17
14 (2.55)
14.31 (1.89)
− 1.52
2.13
15.2 (2.31)
15.2 (1.93)
− 1.59
1.59
0.01
0.000
0.36
0.016
PBBS
10.51 (3.24)
10.19 (3.32)
− 2.47
1.84
9.9 (4.13)
10.15 (3.53)
− 2.87
3.36
11.17 (4.16)
12 (2.45)
− 1.75
3.41
0.29
0.007
0.54
0.024
SFoRC
3.16 (1.54)
3.58 (1.43)
− 0.55
1.40
3.15 (1.28)
3.77 (1.3)
− 0.43
1.66
3.4 (1.45)
2.87 (1.41)
− 1.60
0.54
0.95
0.021
4.14
0.159
FFMQ-SF observing
14.79 (3.29)
15.11 (3.56)
− 1.94
2.57
13.31 (3.45)
13.38 (2.93)
− 2.52
2.67
14.4 (3.04)
15.4 (2.75)
− 1.17
3.17
2.60
0.056
0.88
0.038
FFMQ-SF describing
18.68 (4.22)
19.16 (4.23)
− 2.31
3.25
18.54 (3.91)
19.08 (3.12)
− 2.33
3.41
17.73 (4.79)
18.13 (4.19)
− 2.97
3.77
1.74
0.038
0.01
0.001
FFMQ-SF acting
15.68 (4.82)
15.47 (4.97)
− 3.43
3.01
16 (2.97)
16.77 (3.47)
− 1.85
3.39
13 (4.26)
15.47 (4.09)
− 0.66
5.59
4.36
0.090
2.82
0.114
FFMQ-SF non-judgment
15.21 (4.17)
15.37 (4.9)
− 2.84
3.16
15.31 (4.46)
14.08 (5.84)
− 5.45
2.99
15.67 (5.33)
16.13 (5.67)
− 3.65
4.58
0.20
0.005
1.21
0.052
FFMQ-SF non-reactivity
16.05 (2.66)
16.16 (2.67)
− 1.65
1.86
15.85 (2.54)
16 (2.77)
− 2.00
2.31
16.73 (4.54)
16.8 (4.65)
− 3.37
3.50
0.10
0.002
0.00
0.000
PAQ-S
18.58 (8.87)
14.68 (6.4)
− 9.00
1.21
15.69 (8.25)
14.54 (6.48)
− 7.18
4.87
18.93 (10.33)
14.8 (5.16)
− 10.34
2.08
7.39
0.144
0.66
0.029
DERS-SF awareness
5.42 (1.84)
6 (1.73)
− 0.60
1.75
6 (2.52)
5.85 (2.34)
− 2.12
1.81
6 (2.75)
5.73 (2.46)
− 2.22
1.69
0.04
0.001
1.25
0.054
DERS-SF total
1.76 (0.48)
1.71 (0.54)
− 0.39
0.29
1.76 (0.66)
1.72 (0.68)
− 0.58
0.50
1.67 (0.64)
1.63 (0.65)
− 0.53
0.43
1.17
0.026
0.00
0.000
RPA dampening
20.58 (3.81)
19.11 (3.56)
− 3.90
0.95
19.15 (4.22)
17.08 (3.95)
− 5.39
1.23
19.67 (4.94)
19.67 (3.92)
− 3.34
3.34
5.20
0.106
1.33
0.057
RPA emotion-focused
10.63 (3.29)
10.79 (2.32)
− 1.72
2.04
11.54 (2.57)
9.62 (2.72)
− 4.07
0.22
12 (3.05)
11.87 (2.92)
− 2.37
2.10
3.35
0.071
3.33
0.132
RPA self-focused
9.42 (2.89)
8.37 (2.41)
− 2.81
0.70
9.92 (2.36)
8.23 (2.62)
− 3.71
0.33
10.27 (3.13)
9.2 (2.4)
− 3.16
1.02
20.28
0.315
0.52
0.023
PHQ-9
5.11 (4.32)
4.00 (3.21)
− 3.62
1.41
3.85 (2.82)
4.08 (4.7)
− 2.94
3.41
5.40 (4.72)
5.07 (6.2)
− 4.47
3.80
0.55
0.012
0.53
0.023
VBS visceral body scan, SBS somatosensory body scan, ECM external control meditation, MAIA-2 Multidimensional Assessment of Interoceptive Awareness-2, SIAQ State Interoceptive Awareness Questionnaire, ISAQ Interoceptive Sensitivity and Attention Questionnaire, PBBS Perceived Body Boundaries Scale, SFoRC Spatial Frame of Reference Continuum, FFMQ-SF, Five Facet Mindfulness Questionnaire-Short Form, PAQ-S Perth Alexithymia Questionnaire-Short Form, DERS-SF Difficulties in Emotion Regulation Scale-Short Form, RPA Responses to Positive Affect Questionnaire, PHQ-9 Patient Health Questionnaire-9, 95% CI, 95% confidence interval of the mean differences
We found moderate time effects for the total scores on the MAIA-2, the Not-Distracting subscale of the MAIA-2, the SIAQ, sensitivity to neutral bodily changes (ISAQ), acting with awareness (FFMQ), and the dampening and the emotion-focused positive rumination subscales of the RPA. Specifically, the total sample showed an average tendency to higher levels of interoceptive outcomes (except for the SIAQ, which showed the opposite pattern), higher levels of acting with awareness, and lower levels of positive emotion dampening after the intervention compared to baseline. We also found large time effects for self-focused positive rumination (RPA) and alexithymia (PAQ-S), with a trend to lower scores after the intervention than before.
We found at least medium-size interaction effects (condition × time) for attention to unpleasant bodily sensations (ISAQ), acting with awareness (FFMQ), salience of perceived body boundaries (SFoRC), and emotion-focused positive rumination (RPA) (Fig. 3)
Fig. 3
Box plots for outcome variables with medium or large interaction effects between condition (VBS, SBS, and ECM) and time (pre, post). Note. VBS, visceral body scan; SBS, somatosensory body scan; ECM, external control meditation; ISAQ, Interoceptive Sensitivity and Attention Questionnaire; FFMQ-SF, Five Facet Mindfulness Questionnaire-Short Form; RPA, Responses to Positive Affect Questionnaire
Regarding attention to unpleasant sensations (ISAQ), SBS and ECM groups tended to show an increase from pre- to post-intervention, whereas the VBS group tended to decrease over the same period. A one-way ANOVA for differences between conditions in post-intervention scores on this dimension showed results consistent with a zero effect (F (2,44) = 0.44, ηp2 = 0.020).
Regarding acting with awareness (FFMQ), a tendency to increase from pre- to post-intervention assessment was found for the ECM condition. A one-way ANOVA for differences between conditions in post-intervention scores on this dimension showed results consistent with a zero effect (F (2,44) = 0.42, ηp2 = 0.019).
Regarding the spatial frame of reference, the box plot showed that the ECM tended to report lower scores at post-intervention than the VBS and the SBS groups, whereas their distributions overlapped at pre-intervention. A one-way ANOVA for differences between conditions in post-intervention scores on this dimension showed a medium effect size (F (2,44) = 1.73, ηp2 = 0.073).
Regarding emotion-focused positive rumination (RPA), it tended to decrease in the SBS group from pre- to post-intervention, whereas it remained stable in the VBS and the ECM groups. A one-way ANOVA for differences between conditions in post-intervention scores on this dimension showed a medium effect size (F (2,44) = 2.54, ηp2 = 0.103).
The main effect of condition did not reach a medium size for any of the study variables. Figure S3 (Online Resource 7) shows box plots for all the outcome variables measured at pre- and post-intervention by condition.
Qualitative Data from Participants’ Feedback
A number of notable considerations emerged from the participants’ responses to the open-ended questions.
As positive feedback, participants in the ECM condition reported that meditation helped them to be more aware of details of the environment on a day-to-day basis without judgment (e.g., clutter) and “to connect with the world around me” (Spanish women, 43 years old, employed) while participants in the VBS and SBS conditions reported that they learned to feel their bodily sensations. Participants in all conditions reported that meditation helped them to reduce anxiety, be more present, and be non-judgmental. Participants in all conditions reported experiencing relaxation, calm, peace, well-being, and serenity. Some of them said that these sensations induced by meditation were immediate. What they liked the most was the feeling of relaxation and comfort after meditating, being able to take a moment for themselves during the day, and “get off the automatic pilot” (Spanish man, 25 years old, employed).
On the negative side, the most common difficulties encountered in all conditions were finding the time and place to practice meditation and being easily distracted. It should be noted that a few participants reported feeling anxious because they could not concentrate as much as they wanted to. Participants in all conditions least liked the fact that the meditation audio was the same every day. In addition, some of them pointed out that the pauses after the instructions were too short. Moreover, two participants in the SBS suggested that meditation made them more aware of some muscle problems they already had (e.g., “What I like the most is spending some time with myself, and what I like the least is that it reminds me that I have muscle contractions,” said a 24-year-old employed Spanish woman).
Finally, participants’ blindness to the study hypotheses was confirmed by their responses to the open-ended question about the study hypotheses.
Discussion
In this study, we proposed a study design to test whether focusing attention on different stimuli (i.e., visceral, somatosensory, and external—visual and auditory—cues in mindfulness practice) had differential effects on psychological outcomes. The primary aim of this pilot study was to determine the feasibility of delivering different meditation exercises focused on these three types of sensory stimuli (i.e., visceral body scan -VBS-, somatosensory body scan -SBS-, and external control meditation -ECM-) to adult, non-clinical individuals in an online format. We also aimed to preliminarily investigate whether body scan practice focused on interoceptive vs. somatosensory signals (compared to an external control meditation) might have specific effects on interoceptive and other psychological processes, namely, bodily self-awareness, mindfulness, alexithymia, emotion regulation, and depression.
The target sample size of 15 participants per condition was achieved in a 4-week period. However, it should be noted that the retention rate was more than 10 points below the originally set criterion (80%). Previous research has pointed out dropout as a major barrier to the use of Internet-based interventions. For example, it has been shown that dropout rates in RCT examining the effects of mobile-app-based interventions for chronic disease range from 16 to 63% (Meyerowitz-Katz et al., 2020). Similar rates have been found in other studies (e.g., Lewis et al., 2020; Torous et al., 2016).
Furthermore, among participants who did not withdraw, study adherence was also lower than the initial target rate (70%) for completed meditative sessions (56.53%). The adherence rates found in this study were not very different from those obtained in previous studies testing mindfulness training in non-clinical individuals. However, it is worth noting that most studies did not report this information (Gilmartin et al., 2017). Furthermore, a recent meta-analytic review found that adherence to smartphone-based mental health interventions was less than optimal (Linardon & Fuller-Tyszkiewicz, 2019).
Although we included daily reminders and individualized reports on one’s results as strategies to encourage adherence to the mindfulness practice and study retention, there may have been insufficient motivation to complete the practice. It should be noted that the sample included individuals from the community (primarily Spanish speakers, but also English speakers) who were recruited through social networks and were not actively seeking any type of treatment. Thus, it is possible that studies such as this one might have captured the attention of some people for a short period of time, but that it was soon moved on to other competing online stimuli. In addition, a completely online approach to introducing meditation practice may not have been optimal for inexperienced meditators. Moreover, participant feedback might have shed light on the reasons for the low adherence observed across the board in all experimental conditions in this study.
Participants in all groups complained that the audio recordings were the same every day, which may have led to reduced engagement, and thus, early disengagement from the study. Previous online mindfulness-based interventions using audio recordings for guided practice have typically included a specific audio for specific components or modules of the treatment (Kemper & Khirallah, 2015), which could not be applicable to the current study design focused on examining the effects of a particular mechanism. Other studies investigating audiotaped body scan mindfulness meditation for daily home practice typically involved some type of face-to-face contact with researchers, such as weekly training sessions (Wahbeh et al., 2016) or information and assessment sessions (Fischer et al., 2017; Schultchen et al., 2019). Along these lines, previous research showed that hybrid vs. online interventions offer some advantages regarding usability, which might affect study completion (Ebenfeld et al., 2021). Moreover, some studies also included compensation for participants, either monetary or credit points (Fischer et al., 2017; Schultchen et al., 2019), which is known to decrease attrition rates in smartphone-delivered interventions (Linardon & Fuller-Tyszkiewicz, 2019). A few participants also reported some adverse effects that should not be overlooked. Anxiety and emotional sensitivity (i.e., operationalized as “being annoyed by little things”) were the more common adverse effects reported. Based on qualitative data, they reported not being able to concentrate as much as desired, which could reflect wrong judgments or expectations about the meditation practice.
Despite the unfavorable results in the feasibility aspects noted above, the results of the satisfaction items, supported by qualitative data, indicated a moderate level of acceptability of mindfulness practice in all three experimental conditions of this study. The item on future intention to use the meditation practice of the study had the lowest acceptability ratings, which is congruent with the engagement issues discussed.
Finally, the mindfulness practice quality observed in this study was 8 points below the results found by Del Re et al. (2012) in a small sample of participants who were enrolled in a mindfulness-based stress reduction program (MBSR), at the first week, on the 6-item PQ-M (range, 0–100). However, the mean scores on the single-item PQ-M (range, 1–10) found in our study were more than 1 point above the mean scores observed by Goldberg et al. (2020) throughout MBSR. Thus, the mindfulness practice quality found in this study was not consistently as expected. However, it should be noted that none of these measures has yet been validated in Spanish individuals, so future studies should address this psychometric validation to better draw conclusions about the mindfulness practice quality obtained in this population.
This study revealed certain trends in the three mindfulness-based practices on key interoceptive processes and health-related psychological outcomes. Specifically, the VBS was uniquely related to a decrease in attention to unpleasant bodily sensations (e.g., “When I have difficulty breathing, I focus on that”)—an interoceptive aspect that is related to anxious and somatic symptomatology (Bogaerts et al., 2022; Mehling, 2016)—whereas both the SBS and ECM groups tended to show an increase in this dimension. One possible explanation for this pattern of results is that the VBS group may have developed a greater ability to regulate their attention toward and away from unpleasant visceral sensations. Additionally, participants in this group may have learned to habituate or reinterpret these signals, reducing their salience. This aligned with studies suggesting that interoceptive training can facilitate regulatory mechanisms that mitigate distress associated with bodily sensations (Farb et al., 2015; Khalsa et al., 2018). In contrast, the increase in attention to unpleasant sensations observed in the SBS and ECM groups may reflect different underlying mechanisms. The SBS group may have developed heightened overall sensitivity to bodily sensations, including the unpleasant ones. For the ECM group, it is possible that directing attention away from the body during practice led to a heightened contrast when returning to bodily sensations afterward, ultimately increasing awareness of unpleasant bodily signals. A key question arising from these findings is whether participants in the VBS group perceived visceral sensations as more or less unpleasant than somatosensory sensations before and after the intervention. Future studies could investigate this by incorporating explicit ratings of the valence of visceral and somatosensory sensations, helping to determine whether these group differences arise from the nature of the sensation itself rather than just shifts in attention.
In addition, a surprising unique effect was found for the SBS group: a decrease in emotion-focused positive rumination (e.g., “Think about how happy you feel”), which is a strategy that enhances positive affect. In contrast, it remained stable in the VBS and the ECM groups. While this reduction in the SBS condition may seem counterintuitive, it does not necessarily indicate a maladaptive outcome. Instead, it might reflect a shift toward alternative regulatory strategies, such as acceptance, which is a core aspect of mindfulness-based practices. Future studies should clarify how SBS influences the use of a broader range of positive emotion regulation strategies.
Furthermore, ECM was related to an increase in the level of acting with awareness (i.e., attending to what is happening in moment-to-moment experience), suggesting that shifting attentional focus to external auditory and visual stimuli may have facilitated a broader awareness of the present moment. This could be explained by the possibility that ECM trained the ability to sustain attention on dynamic stimuli in the environment, thereby enhancing the capacity to remain present in everyday moments. In other words, it is possible that the attentional training in ECM generalized more easily to daily life contexts, where attention is typically directed toward external stimuli.
Broadening of the spatial frame of reference (i.e., higher level of selflessness) occurred in both body conditions (i.e., VBS and SBS), which has been related to better stable mental well-being (Dambrun, 2017). Moreover, they were also associated with a decrease in the level of dampening of positive emotions (e.g., “My streak of luck is going to end soon”). Finally, the total sample showed slight decreases in alexithymia scores and increased their overall scores on interoceptive sensibility (MAIA-2) from pre- to post-intervention. No other trend effects were found in the rest of the study variables (e.g., difficulties in emotion regulation of negative emotions or depression).
Given the small sample size of the current pilot study, special caution should be taken in interpreting these preliminary results, which should be considered a descriptive (rather than inferential) approximation of the performance of the interventions examined. Moreover, the low mean level of adherence across all experimental conditions may have biased the results. In particular, the lack of adherence could have blurred the distinctions between the effects of each condition. Conversely, it might have led to the observed trends being attributed to random variation rather than intentional manipulation of our independent variable.
Limitations and Future Directions
Despite the inconclusiveness of the results, this study suggests that focusing on visceral vs. somatosensory signals could represent distinct mechanisms involved in the body scan meditation, based on some unique effects of these conditions. However, they also might have some common trend effects that are not shared with non-bodily, external meditation. This is consistent with previous neuroimaging studies showing the partial overlap of neural networks associated with visceral and somatosensory body signals (Herman et al., 2021; Park & Blanke, 2019; Salvato et al., 2020), as well as evidence of the positive relationship between both visceral and somatosensory processing and mental health (Eshkevari et al., 2012; Khalsa et al., 2018; Macpherson et al., 2021). This study also suggests that clarifying the bodily perceptual mechanisms involved in mindfulness-based training, such as the body scan, may allow for the optimization of designs for different clinical conditions according to their needs.
Although this study may have served as a spur to investigate the research question posed in this paper on a larger scale, a number of amendments to the interventions and procedures studied could be suggested from our findings for large-scale implementation. Specifically, two possible directions emerged. First, a single-session version of the experimental conditions of this study could be tested in a laboratory setting to examine their immediate effects not only on self-report, state measures, but also on physiological and/or neuroanatomical outcomes. Second, a more ecologically valid RCT, in line with the procedures of this pilot study, could be adopted with the following considerations: given the observed recruitment and retention rates, getting collaborators for recruitment could be helpful in achieving a sufficiently large sample size for a large-scale RCT. In addition, the inclusion of parallel versions of the audio recordings for each of the experimental conditions, by avoiding repetition, could increase engagement and thus the adherence and retention rate. Moreover, interactive sessions, either face-to-face or synchronous online, might be beneficial for increasing adherence and ensuring adequate psychoeducation, which could also positively impact safety (by reducing adverse effects), mindfulness practice quality, and acceptability. In addition, the meditation audio recordings themselves should also include psychoeducational cues as reminders. Finally, the duration of each session, as well as the duration of the intervention in a future large-scale study, might need to be longer than 10 min or 1 week, respectively, for its effects to be more detectable. It is worth highlighting that participants were given the flexibility to choose their posture (sitting, standing, or lying down) and whether to keep their eyes open or closed during the meditation practices. This approach aimed to enhance comfort and adherence. However, its impact on the quality of practice remains unknown. Future research should collect and report this information to investigate whether these conditions affect the quality or the benefits of mindfulness-based practices and for whom.
To our knowledge, this is among the first experimental studies aimed at disentangling the effects of attending to different types of bodily cues, which are typically combined or mixed in mindfulness practices such as body scan. However, several limitations of this study should be mentioned as well. First, as mentioned above, the suboptimal retention rate and adherence limited the other results provided in this study. Second, given the nature of pilot studies, the small sample size made it less likely to detect changes due to manipulation of the independent variable. Additionally, effect size estimates might have been prone to fluctuation due to the limited sample. Future research with larger samples is needed to confirm the robustness of the reported effects and ensure their replicability. Third, it should be noted that the interventions in our study differed from those in other mindfulness-based programs, such as MBSR, in several aspects. For instance, while MBSR includes body awareness practices, such as the body scan, as a means to cultivate mindfulness in longer meditation sessions, our interventions incorporated shorter, structured practices in which the body awareness (or the environment awareness in the ECM condition) was the primary focus. In addition, our practices were specifically designed to provide sufficient guidance for non-meditators in an online format. Therefore, direct comparisons with other mindfulness interventions should be made with caution. Fourth, most of the measures used in this study were originally designed to assess trait constructs, and the adaptation made in this study to fit the duration of the intervention has not been psychometrically validated. Along these lines, another limitation was the short duration of the meditation training, as 1 week might have been too short to improve psychological outcomes as intended in this study. Nevertheless, it should be emphasized that the current pilot RCT was foremost designed to assess feasibility rather than meaningful differences in the meditation exercises that were proposed, so the preliminary contribution of this study seems to be able to provide insight for studies following this line of research. Finally, the pilot nature of this study did not allow for cross-cultural comparisons. However, it laid the groundwork for future RCTs by providing the study materials in two different languages.
In conclusion, this study has helped to identify key aspects of the feasibility of different mindfulness-based exercises to better understand the interoceptive mechanisms typically assumed to be involved in meditation practice and their effects on other psychological processes. Hence, future experimental studies could benefit from the insights of this study, ensuring an appropriate design for testing the effects of specific body scan interventions on clinical and well-being outcomes.
Acknowledgements
The authors wish to thank CIBERObn, an initiative of the Instituto de Salud Carlos III (ISC III CB06 03/0052).
Declarations
Ethical
Informed consent was obtained from all participants included in the study prior to their participation in the study. All procedures in studies involving human participants were performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments. The Ethics Committee at the University of Valencia (reference: #2569173) approved the study.
Use of Artificial Intelligence Statement
AI was used to assist in writing, optimizing, and debugging R code for the statistical analyses. The authors carefully reviewed and verified all code and results.
Conflict of Interest
The authors declare no competing interests.
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