Biological Signal Coupling for Integrity

Mechanism

The integrity envelope is the credentialed scope of behaviors an agent is permitted to take in a given context. Its width is computed from a set of contributing fields, of which biological signal is one. Biological signal is admitted into the envelope computation through a credentialed binding: a verified human identity is bound to a stream of physiological observations — heart-rate variability, respiration, gaze, voice spectrography, micro-expression, gait, or other modalities the policy reference admits — and the bound stream is evaluated for coherence against a baseline previously credentialed for that identity.

Coherence is evaluated structurally rather than heuristically. The mechanism computes a coherence score across the admitted modalities, comparing the live stream to the credentialed baseline under a policy-defined tolerance. When the score is within tolerance and the binding remains valid, the biological contribution to the envelope is positive and the envelope widens to admit a defined class of human-coupled actions: contractual commitments, consent-gated disclosures, joint decisions, therapeutic interventions, and other behaviors whose legitimacy depends on a verified, present, and coherent human counterpart. When the score falls below tolerance, when the binding lapses, or when the stream becomes unbound, the contribution is neutral or negative and the envelope narrows correspondingly.

The mechanism is policy-governed end to end. Which modalities count, how they are weighted, what tolerance applies, what baseline a given identity carries, and which behaviors fall inside the wider envelope versus inside the narrower envelope are all specified in the agent's policy reference. The agent's runtime does not interpret biological signal autonomously; it evaluates the credentialed policy against the credentialed signal and records the resulting envelope width as a structural object in lineage.

Operating Parameters

Binding strength is parameterized. The credential that binds an identity to a physiological stream may be strong (multi-modal liveness verification supported by an attested capture device with a hardware root of trust) or weak (single-modal capture from an unattested device). The policy reference defines which envelope widenings each binding strength may support; high-consequence widenings require strong binding, low-consequence widenings may be supported by weak binding, and out-of-policy widenings are simply unavailable regardless of binding.

Coherence tolerance is parameterized per modality and per behavior class. Therapeutic-context behaviors may admit broader physiological tolerance because the counterpart is expected to present atypical baselines; high-stakes contractual contexts may require tight tolerance and explicit liveness. The tolerance profile in force at the time of evaluation is recorded with the envelope, so a downstream auditor can reconstruct which tolerance was applied and why.

Temporal continuity is parameterized. The mechanism distinguishes a steady bound coherent signal from a recently bound signal and from a signal that lapsed and was rebound. Each temporal regime carries its own envelope contribution: a steady signal contributes more than a freshly bound one, and a rebound after lapse contributes only after a re-credentialing window. The continuity model prevents replay-style attacks in which a momentary coherent signal is staged to widen the envelope for a single high-consequence action.

Capability-tier coupling is parameterized. The biological contribution interacts with the agent's declared capability tier so that a tier permitted to take human-coupled actions evaluates the contribution actively, while a tier not permitted such actions ignores biological signal entirely. This prevents over-collection: agents that cannot use the signal do not receive it.

Alternative Embodiments

Embodiments differ in capture surface and binding root. A clinical embodiment uses dedicated medical-grade sensors with regulator-credentialed attestation; a consumer embodiment uses commodity wearables and phone cameras with platform attestation; an enterprise embodiment uses workstation-resident capture under a workforce-identity binding; a field embodiment uses ruggedized capture with hardware-attested keys. Across embodiments, the structural role of biological signal in the envelope computation is unchanged; only the credentialing path differs.

Embodiments differ in modality mix. A voice-first embodiment relies on spectrographic and prosodic features; a vision-first embodiment relies on gaze, micro-expression, and gait; a wearable-first embodiment relies on cardiac and respiratory features; a multi-modal embodiment fuses several. The coherence function is modality-agnostic: it scores the bound stream against the credentialed baseline under a policy-defined weighting, and the weighting is itself a parameter rather than a fixed feature of the architecture.

Embodiments differ in privacy posture. A privacy-preserving embodiment evaluates coherence locally under a trusted-execution environment and emits only the resulting envelope-contribution scalar; a forensic embodiment retains the raw stream under sealed custody for credentialed replay; a federated embodiment aggregates coherence across distributed evaluators that never share raw signal. The envelope outcome is identical across postures; the data-handling chain differs.

Composition With Other Integrity Contributions

Biological signal is one contribution among several to the integrity envelope. Other contributions include declared-policy alignment, lineage-history coherence, peer-attestation status, environmental-sensor integrity, and substrate-attestation status. The envelope at any instant is computed as a credentialed combination of these contributions under the policy reference. A wide biological contribution does not by itself widen the envelope; it widens the envelope only insofar as the other contributions admit widening. Conversely, a narrow biological contribution narrows the envelope even when other contributions would have admitted wider behavior, because the narrowest contributing field governs.

The composition supports human-agent interaction in which the verified presence and physiological coherence of a human counterpart is a structural precondition for specific classes of agent action. A consent-gated medical disclosure is permitted only when the patient's bound coherent biological signal supports the gate; a high-value contractual commitment is permitted only when the counterparty's bound coherent signal is present; a therapeutic intervention is permitted only when the recipient's bound stream is within therapeutic tolerance. In each case, withdrawal of the signal narrows the envelope and the corresponding action becomes structurally unavailable rather than merely discouraged.

Prior-Art Distinction

Conventional biometric systems use physiological signal for authentication: a fingerprint or face match unlocks a session, after which the signal plays no further role. Conventional affective-computing systems use physiological signal as a heuristic input to a model whose output is unconstrained by structural guarantees; the model may modulate behavior on the basis of inferred emotion, but no auditable envelope governs which behaviors are admissible at which inferred state. Neither approach treats biological signal as a structural contribution to a credentialed behavioral envelope, neither binds capability tiers to signal status, and neither records the contribution in tamper-evident lineage.

The disclosed mechanism differs structurally. Biological signal is admitted as a credentialed contribution to a declared envelope; the envelope governs admissibility deterministically; the contribution is recorded with its binding strength, coherence score, tolerance, continuity regime, and resulting envelope delta; and capability-tier coupling prevents agents from receiving signal they may not use. The mechanism is auditable in the sense that an auditor can replay the lineage and reconstruct exactly which signal contributed which envelope width to which action.

Failure Modes and Their Structural Treatment

Several adversarial and incidental failure modes are addressed structurally. Spoofing, in which a synthesized physiological stream is presented to widen the envelope, is mitigated by liveness attestation in the capture path and by coherence comparison against an identity-bound baseline that a generic synthesis is unlikely to satisfy across all credentialed modalities simultaneously. Coercion, in which an authentic but unwilling counterpart is compelled to present a coherent signal, is mitigated by the policy reference admitting duress indicators — modality-specific features associated with non-volitional presentation — that narrow the envelope even when surface coherence is high; the duress profile and its evaluation are credentialed and recorded with the envelope outcome.

Drift, in which a counterpart's authentic baseline shifts over time due to age, illness, or context, is addressed by a credentialed re-baselining process rather than by silent tolerance widening. Re-baselining requires an explicit credentialed event recorded in lineage; envelopes computed before re-baselining are not retroactively reinterpreted. Lapse, in which the bound stream is interrupted by a capture failure or network loss, narrows the envelope immediately rather than persisting a stale wide envelope; the agent's runtime structurally cannot continue to execute human-coupled actions on the basis of a signal that is no longer being received.

Cross-identity confusion, in which the bound stream is correctly received but the binding to identity is mistaken — for example, a different person physically present at a capture device credentialed to another identity — is addressed by liveness-plus-identity attestation in which the credential chain binds not only the device and stream but the identity-specific baseline against which coherence is measured. A mismatched identity produces a low coherence score against the bound baseline and the envelope narrows, even when the substituted physiological signal is itself entirely coherent on its own terms.

Disclosure Scope

The disclosure encompasses the binding of credentialed biological signal to declared identity, the deterministic coherence evaluation against a credentialed baseline, the policy-governed weighting of modalities and tolerance per behavior class, the parameterization of binding strength, temporal continuity, and capability-tier coupling, the structural contribution of the resulting score to the integrity envelope, the composition with other envelope contributions under a narrowest-governs rule, and the recording of all contributing fields in tamper-evident lineage. Application domains include clinical and therapeutic agents, autonomous-vehicle human-presence verification, contractual and consent-gated enterprise interactions, and any human-agent setting in which the legitimacy of agent action depends on a verified, present, coherent human counterpart.

Equivalents within scope include any mechanism that admits credentialed physiological signal as a structural contribution to a declared behavioral envelope under deterministic, policy-governed evaluation, with binding strength, coherence, continuity, and capability-tier coupling recorded in tamper-evident lineage. Embodiments that omit any of these structural elements — for example, treating physiological signal as a heuristic input without envelope coupling, or admitting signal without credentialed binding, or modulating behavior without recording the contribution in lineage — fall outside the disclosed mechanism. The structural commitment is the conjunction of credentialed binding, deterministic evaluation, envelope contribution, and lineage record.