HRV Biofeedback Dissertation Audit — v0.3.5

Audit question

What does the public results-bearing evidence actually support behind the 2026 keynote claim that HRV biofeedback improves emotion regulation and decreases callous-unemotional (CU) traits?

Primary anchor

Maria Petridou doctoral dissertation, University of Cyprus, approved 16 November 2021:

Distinct Neurophysiological Patterns Associated with Differentiated Levels of Antisocial Behaviour, Callous-Unemotional Traits and Anxiety: The Effectiveness of HRV Biofeedback Training with Video Games.

Supervisor: Kostas A. Fanti.

Primary source: https://gnosis.library.ucy.ac.cy/bitstream/handle/7/65328/Maria_Petridou_PhD.pdf?isAllowed=y&sequence=1

Intervention architecture

The intervention combined a conventional HRV biofeedback protocol with Zukor's Drive, an interactive biofeedback video game.

• duration: two weeks;
• six sessions total;
• three sessions per week;
• approximately 30 minutes per session;
• Session 1: determine individual resonance frequency across paced breathing rates;
• Session 2: learn paced breathing pattern;
• Session 3: synchronize HRV with breathing and train above a performance threshold;
• Sessions 4–6: add Zukor's Drive to increase engagement and peak performance.

The dissertation describes the comparison as Intervention versus Waiting List (WL).

Sample and design

The dissertation reports a randomized controlled design and labels it double-blind, but the public text does not make the scope of blinding sufficiently clear for the atlas to treat blinding as independently verified.

Sample-count issue

The dissertation contains internally inconsistent counts across its abstract and methods:

• abstract: 148 participants overall; 93 selected from a longitudinal cohort plus 53 university participants (which itself totals 146);
• methods: 96 selected from the longitudinal cohort plus 53 university participants;
• 110 completed both pre- and post-intervention phases;
• allocation reported as 56 Intervention and 54 Waiting List;
• final physiological sample reported as 106 after technical losses.

The atlas therefore uses N=110 randomized/completing pre-post; N=106 final physiological sample for the intervention audit and separately records the upstream recruitment-count discrepancy.

Pre/post stress protocol

Participants completed the same physiological stress battery before and immediately after the intervention period:

• aversive/affective pictures;
• Stroop task;
• Math task;
• affective/emotional scripts.

Main physiological outcomes included:

• Skin Conductance (SC) reactivity;
• Low-Frequency / High-Frequency HRV ratio (LF/HF).

CU traits, antisocial behavior, and anxiety were used to differentiate participant profiles and test moderation/heterogeneity. In the dissertation's intervention analyses they are not established as equivalent to direct treatment outcomes.

Results that are directly supported

1. Skin-conductance response

The dissertation abstract states that HRV biofeedback with Zukor's Drive increased SC among individuals high in antisocial behavior and CU traits. Task-level analyses indicate that effects varied by stressor and subgroup rather than appearing as one uniform treatment effect.

Interpretation boundary: increased SC indicates altered physiological arousal/reactivity. It is not by itself a direct measure of empathy, symptom remission, or durable behavioral improvement.

2. LF/HF response

The dissertation reports several subgroup-by-intervention effects on LF/HF during stress.

Examples include:

• during affective-picture conditions, reductions differed according to combinations of CU traits, antisocial behavior, anxiety, and intervention status;
• high-CU / low-antisocial participants showed a reported pre/post LF/HF reduction with d≈.74;
• high-antisocial / low-CU participants showed a reported reduction with d≈.69;
• during Stroop, high-anxiety participants in training showed a small LF/HF reduction relative to waiting list (reported d≈.15);
• other tasks produced mixed or null results, including no significant LF/HF effect for affective scripts.

The dissertation summarizes the most clinically relevant pattern as reduced LF/HF under stress among participants with comorbid antisocial behavior, CU traits, and anxiety.

3. Emotion regulation

The dissertation interprets the altered SC and LF/HF response patterns as evidence of improved emotional regulation and clinical potential for heterogeneous antisocial populations.

Atlas classification:

• supported: intervention-related changes in physiological stress-response patterns in selected subgroups/tasks;
• supported as author interpretation: those physiological changes are framed as improved emotion regulation;
• not directly established: broad behavioral or clinical emotion-regulation improvement by an independent distal outcome.

What the dissertation does NOT establish

Direct reduction in CU traits

The public dissertation evidence located in this audit does not demonstrate that CU trait scores themselves decreased following HRV biofeedback.

CU traits are prominently used as a grouping/moderating construct. The intervention's reported results are principally physiological stress-response changes. Therefore the 2026 keynote statement that HRV biofeedback produced "decreases in callous-unemotional traits" currently crosses an evidence boundary that the thesis alone does not support.

Status: keynote claim — source unresolved.

Durable treatment efficacy

The dissertation explicitly identifies absence of follow-up as a limitation. Maintenance of any effect is therefore unknown.

Specific treatment effect beyond nonspecific engagement

The comparator was a waiting list rather than an active/sham biofeedback or game condition. Expectancy, researcher contact, repeated practice, breathing training, and game engagement therefore cannot be cleanly separated.

Important measurement constraint — LF/HF

The dissertation interprets lower LF/HF as improved autonomic/emotional regulation. That interpretation requires qualification.

Modern HRV methodology cautions that LF/HF should not be treated as a direct measure of cardiac sympathetic output or a simple sympathovagal balance. LF power reflects multiple processes, including parasympathetic and baroreflex influences, and interpretation is condition-dependent.

Atlas rule: encode the empirical result as change in LF/HF ratio, then separately encode the author's regulatory interpretation. Do not collapse the two.

Key methodological sources:

• Reyes del Paso et al. (2013), Psychophysiology, DOI 10.1111/psyp.12027.
• Quigley et al. (2024), Psychophysiology publication guidelines, DOI 10.1111/psyp.14604.
• 2026 HRV rigor/reproducibility guidelines, PubMed PMID 42495990.

2024 SSSP continuity

The SSSP 2024 poster title:

Play and Regulate! Can HRV Biofeedback training with video games improve emotional regulation of stress for young adults with differentiated levels of Antisocial Behavior, CU traits, and Anxiety? — Maria Petridou, Kostas Fanti.

The title, population description, constructs, and intervention are highly consistent with the dissertation lineage. The public poster-session programme does not expose results, so it is best treated as a later presentation of the same or closely related HRV-biofeedback programme, not as independent replication.

Manuscript status as of September 2026

Maria Petridou's current University of Limassol profile lists:

Petridou, M., & Fanti, K.A., The effectiveness of HRV Biofeedback training with video game on externalizing and internalizing problems — under review, Journal of Applied Psychophysiology and Biofeedback.

No public results-bearing manuscript was located during this audit. It cannot yet be used as peer-reviewed confirmation of reductions in externalizing/internalizing symptoms or CU traits.

Evidence verdict

Genealogy consequence

This branch should be drawn as:

psychophysiological heterogeneity → HRV/SC identified as candidate regulatory markers → six-session HRV biofeedback + video-game intervention → subgroup/task-specific physiological changes → author interpretation: improved emotion regulation → OPEN GATE: symptom/trait reduction and durability

The atlas must not draw a completed arrow from HRV biofeedback to reduced CU traits until a results-bearing source is recovered.