Keeping an eye on looking measures: Towards more robust developmental methods

A persistent challenge in experimental developmental psychology is determining which of many possible outcome measures best captures underlying behaviors and processes. In the looking-while-listening paradigm for studying early word comprehension, researchers have developed more than 12 distinct outcome measures, but have limited empirical basis for choosing between them. Using archival data from 15 datasets (N = 602 children, 12-60 months), we evaluated these measures' psychometric properties. We found that: (1) proportion looking, reaction time, and proportion of trials switching from distractor to target, demonstrated the strongest validity, robustness (experimental effect size), and reliability; and (2) the paradigm captures two distinct cognitive processes—detecting mismatches and confirming matches—with distractor-initial trials showing stronger developmental sensitivity. This work provides both specific recommendations for word comprehension research and a reproducible framework for evaluating measurement approaches in experimental developmental science.