Abstract
<p>Mindfulness research faces two recurring methodological problems: near-universal reliance on weak control conditions that cannot isolate specific mechanisms from expectancy effects, and systematic exclusion of low-socioeconomic status (SES) populations through design assumptions that presuppose high literacy, quiet private spaces, and contemplative familiarity. We present the Standardized Open-source Mindfulness Architecture (SOMA), a modular stimulus library designed to address both challenges. SOMA comprises 88 audio/script assets: 32 pre-specified Mindfulness–Active Control session pairs across 16 practice modules, written at Grade 5–6 reading level and designed for noisy, shared environments. A pre-registered validation randomised controlled trial (RCT; N = 360; ClinicalTrials.gov NCT07556744) provides proof-of-concept. The data supported the predicted double dissociation (Condition × Measure: F(1, 358) = 185.95, p = 2.2 × 10−34, BF10 ≈ 9.5 × 1063) and experiential equity across SES strata (Hedges' g = −0.07; TOST-confirmed within ±0.40), yet a small credibility gap remained, favouring the Mindfulness condition.</p>