Definition
A cognitive prosthetic is a tool that supports human cognition by absorbing the work the unaided brain reliably drops — much as a leg prosthesis absorbs the work the absent leg would have done. Checklists are the canonical example in Gawande's The Checklist Manifesto; the frame extends to calendars, runbooks, dashboards, post-mortem templates, and any other deliberately external memory or attention aid.
The framing is non-pejorative. A surgeon using a checklist is no more diminished than a runner using a stopwatch. The prosthetic compensates for a known limit — in this case, the working-memory and attention limits of even expert humans under load.
Why it matters
How it works
The design loop is straightforward. First, name the cognitive limit you are trying to support: working memory under load, attention over a long shift, prospective memory across days, accurate self-assessment under pressure. Second, design an instrument that targets that limit specifically — a short list at a pause-point for working memory, an alarm for time-bound attention, a calendar entry with context for prospective memory. Third, make using the instrument cheap enough at the relevant moment that the expert will actually reach for it. Boorman's surgical-checklist budget of 60–90 seconds and Pronovost's five-step central-line list are both engineered around this third point.
The deepest claim of the cognitive-prosthetic frame is that expertise has limits the expert cannot reliably see. Tools that respect those limits are not insults to expertise; they are how expertise scales.