Abstract This article proposes the Ability‐Attenuated 3PL (AA‐3PL), an extension of the three‐parameter logistic model designed to represent systematic discrepancies between latent ability and expressed performance (the ability‐expression gap). The model retains the conventional interpretation of 3PL item parameters while adding a parsimonious mechanism to capture structured performance attenuation that can arise from non‐ability influences in longitudinal and applied testing contexts. Evidence is established through a Bayesian simulation program spanning multiple study modules, including baseline multistage conditions, shape‐misspecification stress tests, identification‐constraint checks, a growth‐related extension, a one‐stage boundary case, and prior‐sensitivity analyses. Across attenuation conditions, AA‐3PL consistently reduces difficulty misattribution and improves overall model performance, while showing negligible differences from 3PL when no gap is present; robustness depends on aligning the attenuation shape with the underlying data pattern. An empirical two‐wave WJ‐PV illustration provides convergent support: AA‐family models better capture follow‐up systematic deviations than 3PL, with the shift‐augmented extension offering the most coherent improvements when cross‐wave shifts are present.
Tien‐Yu Hsieh (2026) studied this question.