research-package · RP-PROD-002
Operationalizing Product Legibility
Product Legibility can be measured, but not responsibly as a context-free aesthetic score. The evidence supports a task-, population-, and environment-specific profile built from six gates: action possibility, discoverability, interpretability, executability, feedback closure, and consequence comprehension. A single average is unsafe because severe failure in one critical dimension can be concealed by strength elsewhere. This REP replaces the proposed additive score with a gated measurement architecture, distinguishes diagnostic metrics from outcome metrics, and provides a repeatable Product Legibility Evaluation Protocol. It also finds that classic predictive laws such as Fitts' and Hick's are useful locally but cannot serve as universal product-quality laws without checking their assumptions.