T = a + b·log2(D/W+1)A two-layer model of why interface interaction and technology uptake diverge with age: a live, clickable Fitts's-Law UI test on the left, and a per-cohort diffusion-of-innovation S-curve on the right.
Every click is a genuine Fitts's-Law trial: T = a + b·log2(D/W+1), where D is the on-screen distance to the target and W is its width (set by the accessibility slider). The Age and Experience sliders raise the model's a (base perceptual-motor latency) and b (sensitivity to difficulty), which in turn widen a short "not-yet-armed" window on each new target and increase cursor tremor — so higher age genuinely produces slower, less accurate real clicks, not a scripted number.
The right-hand chart plots a logistic adoption curve A(t) = L / (1+e^(−k(t−t₀))) for five age cohorts. Older cohorts get a later midpoint t₀, a shallower slope k, and a lower ceiling L — the compounding lag and incomplete saturation documented in digital-divide research. Click a cohort chip to inspect it.
Left-click the highlighted target to play the interface test; right-drag or pinch to look around the panel; use the sliders to change test-user age, UI element size, training level and game pace.