The receptivity edge
A score per member, per window — variable-ratio timing, the most durable schedule in behavioral science.
Display mode never touches PHI — no BAA required. Start in 5 minutes.
Same shaded window every day. The delivery minute is drawn at random inside it — no minute is favored.
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Same window Random minute By design
§1 · The receptivity threshold
Two curves, one crossing point. The dashed curve is what we usually optimize for — a message's content quality, its source authority, the clarity of the call to action. The solid curve is what actually predicts behavior change — the patient's state at the moment the message arrives. The crossing point is where the message becomes more important than the readiness to receive it. Below it, even a perfectly crafted message bounces off.
Health-content products that ignore the solid curve compete on the dashed one — better copy, better data, better claims. Signal competes on the solid curve. Every cue carries a 0–1 receptivity score that tells you which side of the threshold this patient is on right now. You spend your copy budget where it matters; we tell you when your copy actually has a shot.
The score is built from three configurable inputs (see §2). It does not require any data we don't already have — no biometric stream, no wearable integration, no extra patient-facing form. The inputs are what every cued-stream product already collects.
§2 · Anchor-and-jitter mechanic
Receptivity is not a black box. The score is built from three knobs that each side of the contract — patient, partner, Uphealth — gets to turn.
Illustrative pattern — the shape of the mechanism, not one member’s data.
Knob 1
The patient picks the time-of-day window — for example, "morning routine, 7 to 9 AM." That's the anchor; the patient knows roughly when a message arrives. Inside that window the minute is unpredictable — that's the jitter. Same window every day, different minute. Variable-ratio reinforcement (Skinner) — the schedule pattern that drives the most durable behavior in animals + humans alike — built into delivery, no per-template tuning required.
Knob 2
The template defines the arc length and the message frequency. A 30-day Pharma Init arc fires once a day; a Wellness arc fires three times a week; a Postpartum arc tapers from daily to weekly over six months. The cadence is a property of the template, not a knob the patient turns mid-arc — switching cadence means switching templates.
Knob 3
Every message carries include/exclude audience tags. The patient's roster carries matching tags. The intersection determines which messages are even in the pool for this patient's next cue. The receptivity score is computed across the in-pool set only; an excluded message doesn't drag down the score.
Why anchor-and-jitter, not "send at the optimal time"
"Optimal time" delivery — picking the single best minute for each patient — sounds great and degrades fast. The patient adapts to the predictable clock time, the message becomes background, the open rate decays. Anchor-and-jitter trades a small amount of predictability (the window) for a large amount of novelty (the minute) — mere-exposure habituation is defeated structurally, not via per-message tuning.
This isn't a hunch — it's measured. Because our engine draws the delivery minute at random inside the member's window, our logs form a running randomized experiment over send minutes — evidence a fixed-schedule sender can never produce. The verdict strengthens the design: within a window the member chose, no clock minute beats another. Clock time is not where response lives — novelty and member state are, which is exactly what variable-ratio delivery is built to use.
The behavioral-science substrate: variable-ratio reinforcement (Skinner) drives persistence; novelty + anticipation (Berlyne) drives attention; mere-exposure habituation (Zajonc) is what we're defeating. None of this is new — it's the same mechanism that makes slot machines, social-media feeds, and unread-message badges work. Signal applies it to a health-content channel, where the goal is durable behavior change rather than dwell time.
§3 · The score
Every cue response includes a receptivity field — a single float between 0.00 and 1.00. The number is advisory: it tells you Signal's confidence that this patient is above the threshold right now. What you do with it is up to your mode.
Display mode
You decide what to do with it
Deliver mode
Reach composes it for you
§4 · Signal vs Reach
Two questions, one decision. Signal answers "what is the right next message for this patient on this arc day?" Delivery intelligence answers "should this person get any message right now, and on what channel?" — then draws a random minute inside the window. In Display mode you read the score and decide; in Deliver mode delivery intelligence resolves the action for you.
Action
Send → email, jittered to 7:48 am
Why: tier is Open and the window is live; push has softened, so email carries the cue; the minute is drawn at random inside the window — the unpredictability is deliberate.
The receptivity score sets when. The readiness tier sets how hard to push. Together they resolve the one question that matters about every message: send it now, somewhere else, later, or not at all.
That engine is delivery intelligence — it ships inside every Signal cue.
SIGNAL
Picks the message · advisory
REACH
Picks the moment · binding
TOGETHER
What + when (decided)
A buyer running Deliver mode calls Signal once a day per active patient. Signal returns the next message + receptivity 0.74. Reach receives the message + the score + the patient's window setting, picks a random minute inside the 7-9 AM window (jitter), checks deliverability (Land), and sends. If Land says the address is failing, Reach swaps to a fallback channel. If receptivity is below 0.3 and the message-class tier is "Quiet," Reach holds for the next day's cue. The buyer sees one webhook per actually-sent message; everything else is silent + auditable.
§5 · Display vs Deliver
Receptivity is returned with every cue in both modes. What changes between modes is who renders the message, who picks the minute, and whether real PHI passes through Uphealth.
Display
Buyer renders · default
Deliver
Uphealth sends · opt-in
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