Decision-Making Capacity Threshold Simulator

Clinical Scenario

Pick a scenario, or set the risk slider and interview scores yourself.

Decision risk / gravity 50

Capacity Interview (MacCAT-style)

Understanding 70

Appreciation 70

Reasoning 70

Expressing a choice 70

Determination

Capacity present — decision stands

Composite score

70.0

Required threshold

50.0

Weakest domain

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How it works

Bioethics and law (Appelbaum & Grisso's four-abilities model, embedded in tools like the MacCAT-T) assess decisional capacity along four criteria: understanding the diagnosis and options, appreciating how they apply to one's own situation, reasoning through the trade-offs, and being able to express a stable choice.

Courts and clinicians then apply the sliding-scale standard (Drane; Buchanan & Brock): the bar for capacity is not fixed — it rises with how much harm a wrong choice could cause. Refusing a lunch tray needs almost no capacity to respect; refusing life-saving treatment demands a much higher, more carefully verified capacity.

Composite = 0.30·Understanding + 0.30·Appreciation + 0.25·Reasoning + 0.15·Choice
Threshold(risk) = 20 + 0.6 · risk        (20 at trivial risk → 80 at extreme risk)
Capacity met  ⇔  Composite ≥ Threshold(risk)

Case buttons — load a real dilemma's typical risk level and a plausible interview profile.
Risk slider — how much harm a wrong choice could cause; raises the threshold plane in the 3D view.
Four interview sliders — simulate how the patient scored on each capacity domain during a structured interview.
When the composite bar clears the plane, the disk glows green and the patient's own choice is respected (autonomy); when it falls short, it glows red and a surrogate/best-interest decision-maker is triggered (beneficence) — this is exactly the trade-off between respecting autonomy and protecting a vulnerable patient that makes capacity assessment ethically fraught, not just clinical box-checking.

Understanding Appreciation Reasoning Choice Threshold plane

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