RESUMO
Math-intensive fields in postsecondary education, such as physics and math, often struggle with high student dropout rates. Motivational declines after the transition to postsecondary education are a key factor underlying students' achievement difficulties and decisions to leave these fields. A better understanding of which motivational factors play a particularly central role in predicting achievement difficulties and dropout decisions is needed to inform potential interventions. Thus, drawing on Eccles' expectancy-value theory, we examined changes in the relative importance of students' expected success and different task values as unique or joint predictors of students' academic success and course dropout across three time points within a semester. Data were collected in gatekeeper math courses for physics and math majors (N = 811). Commonality analyses showed an increasing overlap in the predictive effects of students' expectancies and values on later academic outcomes, which indicates convergence in these motivational beliefs, as they likely influence each other over time. A significant shift in the relative importance of students' expectancies and values occurred after the transition to postsecondary education, highlighting a sensitive time point for interventions. Pre-existing achievement, socioeconomic, and gender differences lost some of their unique predictive power toward the midpoint of the semester.