SOMA Validation RCT: Testing Structural Equivalence and Mechanistic Orthogonality of an Open-Source Mindfulness Stimulus Library (SOMA-VAL)

The Standardized Open-source Mindfulness Architecture (SOMA): A Modular, Equity-Engineered Stimulus Library for Mechanistic Mindfulness Research

Background: Mindfulness research faces two structural problems. First, weak active control conditions make it impossible to isolate specific mechanisms from expectancy and non-specific effects. Second, most protocols systematically exclude low-socioeconomic status (SES) populations through design assumptions that presuppose high literacy, quiet private spaces, and familiarity with contemplative practice.

Objective: This study validates the Standardized Open-source Mindfulness Architecture (SOMA), the first modular, open-source stimulus library purpose-built to address both challenges simultaneously. SOMA comprises 88 distinct audio assets organized around 16 sensory practice modules, each paired with a structurally equivalent active control script engineered to induce analytically orthogonal cognitive processing.

Design: Pre-registered randomized controlled trial using a 2×2 mixed design (Condition [Mindfulness vs. Active Control] × Measure [State Mindfulness Scale vs. Analytical Engagement Scale]), with quota sampling to ensure equal representation of participants with and without a university-level degree (n = 180 per SES stratum).

Setting: Online, via Prolific Academic recruitment platform and Qualtrics survey software.

Participants: N = 360 English-proficient adults aged 18 years and older (or the applicable minimum age of majority in the participant's country of residence) without a current mental health diagnosis or treatment, and without a current meditation practice.

Intervention: Each participant listens to a single 12-minute audio-guided exercise. Participants are randomly assigned to either the Mindfulness condition or the Active Control condition, and within that condition to one of 16 practice scripts. Mindfulness scripts guide bottom-up experiential awareness; Active Control scripts guide top-down analytical processing of the same everyday activities.

Primary Outcomes: (1) Credibility and expectancy equivalence between conditions (H1: Two One-Sided Tests on Credibility and Expectancy Questionnaire composite, equivalence bounds d = ±0.40); (2) mechanistic double dissociation - higher state mindfulness in the Mindfulness condition and higher analytical engagement in the Active Control condition (H2: 2×2 mixed ANOVA, interaction term as primary criterion).

Exploratory Outcome: SES-related differential experiential accessibility (H3: independent-samples t-test plus equivalence test on Semantic Differential composite by SES group).

Study Overview

• Status: Not yet recruiting
• Conditions: Healthy Volunteers; Mindfulness
• Intervention / Treatment: Behavioral: SOMA Audio-Guided Mental Training Exercise

Detailed Description

The SOMA Validation RCT is a proof-of-concept deployment of the Standardized Open-source Mindfulness Architecture (SOMA) library, testing whether the library's two core design goals - mechanistic orthogonality between Mindfulness and Active Control conditions, and equitable accessibility across socioeconomic strata - have been achieved before the library is used in large-scale multi-site efficacy trials.

The study uses a randomized, single-blind, parallel-group 2×2 mixed design. Each participant is randomly assigned to either the Mindfulness condition or the Active Control condition and listens to a single 12-minute audio track. Within each condition, participants are further randomized to one of 16 practice scripts, with approximately equal allocation across scripts. Mindfulness and Active Control scripts are structurally matched on duration, word count, and narrator voice, and cover the same 16 everyday activities and sensory domains - the difference lies exclusively in the cognitive mechanism targeted. Blinding is achieved via a neutral cover story framing both conditions as "Mental Efficiency Training." Researchers analyzing data are not blinded.

Three pre-registered hypotheses are tested. H1 (confirmatory) tests whether the Active Control condition is perceived as equally credible as the Mindfulness condition, using Two One-Sided Tests (equivalence bounds d = ±0.40, one-sided α = .05) on the Credibility and Expectancy Questionnaire (CEQ) composite, with script assignment as covariate. H2 (confirmatory) tests whether the two conditions produce a mechanistic double dissociation - Mindfulness greater than Active Control on the State Mindfulness Scale (SMS) and Active Control greater than Mindfulness on the Analytical Engagement Scale (AES) - using a 2×2 mixed ANOVA (Condition × Measure). The interaction term is the primary confirmatory criterion (α = .05); planned one-tailed contrasts provide confirmatory directional evidence. The SMS measures bottom-up experiential awareness; the AES, developed specifically for this study, measures top-down analytical engagement. H3 (exploratory) tests whether Low-SES and High-SES participants show equivalent experiential responses on a Semantic Differential composite, using an independent-samples t-test plus equivalence test (bounds d = ±0.40).

Primary analyses follow an intention-to-treat approach: all participants who completed the study are included regardless of performance on the Script Comprehension Check. A pre-specified sensitivity analysis repeats all primary analyses excluding participants who fail both Script Comprehension Check items. In the unlikely event that the target N of 360 is not reached within four weeks of launch, data collection will close and analyses will proceed on the achieved sample, with any shortfall reported transparently as a deviation.

Quota sampling is used at the recruitment stage to ensure n = 180 per SES stratum (Low-SES: no university-level degree; High-SES: university-level degree or higher), recruited via two linked studies on the Prolific Academic platform with mutual exclusion between studies. SES is not used as a stratification variable at the randomization stage.

Full pre-registration, analysis code with simulated data, and all stimuli are available at osf.io/m76cg.

• Study Type: Interventional
• Enrollment (Estimated): 360
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Alessandro Sparacio, Ph.D. in Psychology; Phone Number: 8072 8247; Email: Alessandro_Sparacio@a-star.edu.sg

Study Locations

• Singapore
  • Singapore, Singapore
    • Online
    • Contact: Alessandro Sparacio, Ph.D. in Psychology; Phone Number: 8072 8247; Email: Alessandro_Sparacio@a-star.edu.sg

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

Aged 18 years or older (or the legal age of majority in the participant's country of residence, whichever is higher)

Fluent in English (English as first language or self-reported fluent language)

Able to listen to a 12-minute audio recording with headphones, earphones, or device speaker

Access to a device capable of completing an online survey

Exclusion Criteria:

Current diagnosis of a mental health condition

Currently receiving or waiting for treatment for mental health symptoms (e.g., psychological therapy or psychiatric medication)

Regular yoga or meditation practice in the last six months

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Mindfulness Condition; Participants listen to one 12-minute SOMA Mindfulness audio track randomly assigned from 16 script pairings. Tracks guide bottom-up experiential awareness of everyday sensory and bodily experience (e.g., body scan, mindful walking, mindful eating, awareness of breath). All tracks are narrated by the same voice actor under identical recording conditions.	Behavioral: SOMA Audio-Guided Mental Training Exercise; A single 12-minute audio-guided exercise from the Standardized Open-source Mindfulness Architecture (SOMA) library. The SOMA library comprises 88 distinct assets organized around 16 sensory practice modules (formal and informal) paired with structurally equivalent active control scripts. All materials are equity-engineered to a Grade 5-6 reading level, deployable without a meditation teacher, and free under CC BY-NC-SA 4.0 (osf.io/m76cg).
Active Comparator: Active Control Condition; Participants listen to one 12-minute SOMA Active Control audio track matched to the same practice domain as the assigned Mindfulness track. Tracks guide top-down analytical processing of the same activities (e.g., seating area analysis, spatial navigation exercise, meal organization, weekly schedule optimization). Matched to Mindfulness tracks on duration (±30 seconds), word count (898-957 words), narrator voice, and recording conditions.	Behavioral: SOMA Audio-Guided Mental Training Exercise; A single 12-minute audio-guided exercise from the Standardized Open-source Mindfulness Architecture (SOMA) library. The SOMA library comprises 88 distinct assets organized around 16 sensory practice modules (formal and informal) paired with structurally equivalent active control scripts. All materials are equity-engineered to a Grade 5-6 reading level, deployable without a meditation teacher, and free under CC BY-NC-SA 4.0 (osf.io/m76cg).

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Credibility/Expectancy Questionnaire (CEQ) composite score	CEQ composite 3-item composite (Logic, Success, Recommendation) from the Credibility and Expectancy Questionnaire (Devilly & Borkovec, 2000), each item rated on a 1-9 scale (1 = not at all, 9 = extremely). Composite score range: 1-9; higher scores indicate greater perceived credibility and expectancy. Primary outcome for H1 (structural equivalence).	Immediately after audio exposure (single time point)
Mechanistic Double Dissociation: State Mindfulness Scale and Analytical Engagement Scale Interaction Score	State Mindfulness Scale (SMS; Tanay & Bernstein, 2013): 7 items rated 1-5 (1 = not at all, 5 = very well); range 1-5, higher scores indicate greater state mindfulness. Analytical Engagement Scale (AES; purpose-built for this study): 5 items rated 1-5 (1 = not at all, 5 = very much); range 1-5, higher scores indicate greater analytical engagement.	Immediately after audio exposure (single time point)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Semantic Differential scale	Three bipolar 7-point items assessing subjective experiential quality of the exercise: Sensing/Feeling vs. Analysing/Estimating; Judging/Correcting vs. Accepting/Allowing; Past or Future vs. Here and Now. Composite score range: 1-7; higher scores indicate a more mindfulness-consistent experiential quality.	Immediately after audio exposure (single time point)

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
CEQ Item 3 (Wellbeing) - exploratory	Single item assessing emotional outcome expectancy, analysed separately from the primary H1 composite.	Immediately after audio exposure
Perceived Nature / Blinding Check	Mechanism identification item (categorical, 5 options) and confidence rating slider (0-100%). Outcome-neutral quality check for blinding adequacy.	Immediately after audio exposure
Audio Clarity, Cognitive Demand, Instruction Clarity	Outcome 6a - Audio Clarity Single item: "How clear was the audio quality of the recording?" rated on a 5-point scale (1 = very unclear, 5 = very clear). Reported descriptively. Outcome 6b - Cognitive Demand Single item: "How mentally demanding did you find this exercise?" rated on a 5-point scale (1 = not at all demanding, 5 = extremely demanding). Reported descriptively. Outcome 6c - Instruction Clarity Single item: "How easy was it to follow the instructions in the exercise?" rated on a 5-point scale (1 = very difficult, 5 = very easy). Reported descriptively.	Immediately after audio exposure

Collaborators and Investigators

• Sponsor: Institute for Human Development and Potential (IHDP), Singapore
• Collaborators: Charles University, Czech Republic; The University of Queensland

Publications and helpful links

General Publications

• Devilly GJ, Borkovec TD. Psychometric properties of the credibility/expectancy questionnaire. J Behav Ther Exp Psychiatry. 2000 Jun;31(2):73-86. doi: 10.1016/s0005-7916(00)00012-4.
• Tanay G, Bernstein A. State Mindfulness Scale (SMS): development and initial validation. Psychol Assess. 2013 Dec;25(4):1286-99. doi: 10.1037/a0034044. Epub 2013 Sep 23.
• Sparacio A, Davies JN, Lee E, Schmitt JAJ. Feasibility and Acceptability of a Smartphone-Delivered Mindfulness Intervention for Stress Reduction in Adult Singaporeans: Pilot Randomized Controlled Trial. JMIR Ment Health. 2025 Aug 19;12:e77793. doi: 10.2196/77793.
• Sparacio A, IJzerman H, Ropovik I, Giorgini F, Spiessens C, Uchino BN, Landvatter J, Tacana T, Diller SJ, Derrick JL, Segundo J, Pierce JD, Ross RM, Francis Z, LaBoucane A, Ma-Kellams C, Ford MB, Schmidt K, Wong CC, Higgins WC, Stone BM, Stanley SK, Ribeiro G, Fuglestad PT, Jaklin V, Kubler A, Ziebell P, Jewell CL, Kovas Y, Allahghadri M, Fransham C, Baranski MF, Burgess H, Benz ABE, DeSousa M, Nylin CE, Brooks JC, Goldsmith CM, Benson JM, Griffin SM, Dunne S, Davis WE, Watermeyer TJ, Meese WB, Howell JL, Standiford Reyes L, Strickland MG, Dickerson SS, Pescatore S, Skakoon-Sparling S, Wunder ZI, Day MV, Brenton S, Linden AH, Hawk CE, O'Brien LV, Urgyen T, McDonald JS, van der Schans KL, Blocker H, Ng Tseung-Wong C, Jiga-Boy GM. Self-administered mindfulness interventions reduce stress in a large, randomized controlled multi-site study. Nat Hum Behav. 2024 Sep;8(9):1716-1725. doi: 10.1038/s41562-024-01907-7. Epub 2024 Jun 11.

Helpful Links

• The OSF page of the project with all the relevant study documentation.

Study record dates

Study Major Dates

• Study Start (Estimated): May 5, 2026
• Primary Completion (Estimated): May 31, 2026
• Study Completion (Estimated): May 31, 2026

Study Registration Dates

• First Submitted: April 13, 2026
• First Submitted That Met QC Criteria: April 22, 2026
• First Posted (Actual): April 29, 2026

Study Record Updates

• Last Update Posted (Actual): May 4, 2026
• Last Update Submitted That Met QC Criteria: April 28, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: Mindfulness; Randomized Controlled Trial; Socioeconomic Status; Active Control; Expectancy; Open Science; Stimulus Library; Mechanistic Research; Credibility
• Other Study ID Numbers: ASTAR-IHDP-2025-108-SOMA-VAL; osf.io/m76cg (Registry Identifier: Open Science Framework); 2025-108 (Registry Identifier: A*STAR Institutional Review Board)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: De-identified participant-level data will be shared in a public repository (Open Science Framework, osf.io/m76cg) after study completion and publication. The dataset will include all survey responses (excluding any inadvertently identifying information) and the analysis code needed to reproduce all reported results. Data sharing is a pre-specified condition of participation and is disclosed in the participant information sheet.
• IPD Sharing Time Frame: De-identified individual participant data and all supporting information will be available on the Open Science Framework (osf.io/m76cg) within 12 months of primary study completion. Data will remain publicly accessible indefinitely.
• IPD Sharing Access Criteria: Open access. No registration or application required. All de-identified data, analysis code, study protocol, statistical analysis plan, and informed consent form will be freely available for download at osf.io/m76cg. Data are shared under CC BY-NC-SA 4.0 - free for academic, clinical, and public research use.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF; ANALYTIC_CODE

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No