Construct-Validity Slippage in Psychological Measurement: Quiet Eye as a Case Study in Behavioral Inference

Psychological science routinely relies on behavioral measures to infer latent cognitive processes, yet the progression from measure to construct presents persistent inferential challenges. This paper introduces construct-validity slippage, an inferential vulnerability that arises when repeated empirical convergence progressively strengthens confidence in behavioral scores beyond the evidence supporting their meaning. Drawing on contemporary validity theory, the paper proposes an inferential chain linking theoretical assumptions, operational definitions, behavioral indicators, score meaning, and construct inference. The Quiet Eye (QE) literature is used as a case study to illustrate how a robust behavioral measure has accumulated strong empirical support while progressively acquiring broader psychological interpretations, including attentional control, motor preparation, cortical activation, and perception–action coupling. The paper argues that future construct validation should integrate operational definitions, measurement technology, and theoretical interpretation. More broadly, construct-validity slippage provides a framework for identifying when confidence in behavioral measures begins to exceed the evidence supporting construct interpretation.