Clay field therapy for complex PTSD: a single-case study with HRV measurement

Figures

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  Figure 1. The eight haptic praxes observed during CFT. Schematic representation of the eight generic categories of haptic praxes performed during therapeutic clay work (27): Pressing, Squeezing, Kneading, Gliding, Digging, Covering, Releasing/Throwing, and Shaping. Each praxis is defined by a set of standardized observational descriptors enabling the coding of haptic gestures produced during CFT sessions. HAPTIC, Haptic Analysis and Processing of Therapeutic Interactions with Clay; CFT, Clay Field Therapy (28).

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  Figure 2. Temporal structure of a CFT session: three phases and reference conditions. Organization of a session into Phase 1 (verbal stabilization; mean duration: 7 min 10 s, SD = 2.9), Phase 2 (haptic work; mean duration: 63 min, SD = 14.24), and Phase 3 (verbal integration; mean duration: 6 min 16 s, SD = 2.7). The 3F (first 3 minutes) and 3L (last 3 minutes) segments used as reference conditions are indicated. CFT, Clay Field Therapy; 3F, first 3 minutes; 3L, last 3 minutes.

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  Figure 3. Within-session SDNN and RMSSD profiles across the 10 clay field therapy sessions. CFT, Clay Field therapy; SDNN, Standard Deviation of NN intervals; RMSSD, Root Mean Square of Successive Differences; MRR, Mean RR interval. Each panel displays window-by-window values (3-min epochs) for one session, with SDNN in the upper row and RMSSD in the lower row. Panel color encodes the dominant autonomic profile family named in the session label, not the individual session; sessions sharing a profile share a color. Orange denotes profiles of sympathetic co-activation and instability (S1, S3, S8, S9), gray denotes low-baseline tonus profiles (S2, S7), and the remaining colors denote singular profiles (S4, dark red; S5, green; S6, purple; S10, blue). The dashed line indicates the baseline level, computed as the mean of all windows excluding spike windows. Spike windows (MRR > 900 ms) are marked with a downward triangle (▼) and excluded from baseline computation. Phase backgrounds indicate the three therapeutic phases: Phase 1 — Stabilization & safety (yellow); Phase 2 — Clay fieldwork (session color); Phase 3 — Integration & consolidation (green). Session labels reflect the dominant autonomic…

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  Figure 4. Within-session change in LF/HF ratio (FFT) between the first 3 minutes (3F, circles) and the last 3 minutes (3L, squares) across the 10 CFT sessions, sorted by ascending 3F value. CFT, Clay Field Therapy. Each line represents an individual session (S1–S10), sorted from lowest (top) to highest (bottom) 3F value. Numerical values indicate observed 3F and 3L measurements. Green = sessions with high initial sympathetic dominance (3F) converging toward lower LF/HF at 3L (vagal rebalancing); orange = sessions with low 3F LF/HF diverging toward higher values at 3L (residual sympathetic activation); gray = mixed profile. Given the exploratory nature of this analysis (n = 10 sessions, single-case design), no inferential statistics are reported.

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  Figure 5. Distribution of SDNN by therapeutic phase of CFT and relative position with respect to normative reference values (n = 10 sessions). CFT = Clay Field Therapy. Phase 1: stabilisation and safety (n = 10, mean duration = 7 min 10 s, SD = 2.9); Phase 2: haptic work (n = 10, mean duration = 63 min, SD = 14.24); Phase 3: integration and consolidation (n = 10, mean duration = 6 min 16 s, SD = 2.7). The shaded area represents the normative ±1σ interval for SDNN (134.9 ± 34.2 ms; 44). Horizontal bars indicate the phase mean calculated on valid values only (Phase 1: 154.4 ms, n = 9; Phase 2: 140.9 ms, n = 10; Phase 3: 129.8 ms, n = 9). Open circles indicate values outside the ±1σ interval. Grey crosses indicate values excluded from comparative analyses due to movement artefacts identified during visual inspection of the recordings: S6-start (SDNN = 594.53 ms) and S4-end (SDNN = 720.76 ms).

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  Figure 6. Autonomic profiles and haptic engagements in session 10: window-by-window analysis. Panel (a) Window-by-window evolution of global cardiac variability (SDNN, ms, solid line) and vagal tone (RMSSD, ms, dashed line) during session 10. Colored bands indicate normative reference intervals: green (± 1σ, 101–169 ms), orange (± 2σ, 66–203 ms), and red (beyond ±2σ, > 203 ms); the horizontal dotted line demarcates the +3σ threshold (238 ms). Vertical dashed lines mark the two major autonomic peaks: Peak 1 (12:02 min, orange line) and Peak 2 (29:59 min, blue line). Panel (b) Evolution of the LF/HF ratio computed by FFT spectral analysis (orange line, circles) and AR analysis (blue dashed line, squares) for the same time windows. Colored bands delimit zones of parasympathetic predominance (LF/HF < 1, green), sympathovagal balance (LF/HF 1–2, orange), and sympathetic predominance (LF/HF > 2, red). Panels (a, b) — Video frames synchronized to the two autonomic peaks (28). Panel (a) (12:02 min): high-intensity symbolic support shaping, coinciding with Peak 1 (SDNN = 460 ms, LF/HF FFT = 18.52). Panel (b) (29:59 min): maximum-intensity symbolic internalization shaping, coinciding with Peak 2…