Psychometric Perspectives on Shyness Across the Lifespan: Measurement Invariance and Mean-Level Differences in Ages 4–86

This study examined mean-levels of shyness from childhood to senescence. To improve validity in our shyness measure across age, we used two different but comparable shyness scales in adult and child/adolescent datasets that were created separately within a repeated cross-sectional design. In the adult analysis (N?=?1,294, ages = 17?86), measurement invariance (through multi-group confirmatory factor analysis and the alignment method) was established among age groups but not between the sexes; only comparisons across age were considered valid. Significant mean differences among adult groups indicated shyness followed an inverted U-shape pattern. In the child/adolescent sample (N?=?554, ages = 4?16), measurement invariance was found across sex but not age groups. Mean differences in adult shyness might have been tied to age-related social processes and measurement validity may have limited accurate assessment of shyness across child/adolescence. Issues associated with the validity of measuring shyness across the lifespan are discussed.