Feedback can only be effective when students seek feedback and process it. This study examines the relations between students' motivational beliefs, effort invested in a computer-based formative assessment, and feedback behaviour. Feedback behaviour is represented by whether a student seeks feedback and the time a student spends studying the feedback. The motivational beliefs examined in this study are success expectancy and task-value beliefs. Results show that the effort invested in the formative assessment was predicted by task-value beliefs, but not by success expectancy beliefs. Furthermore, feedback seeking was predicted by success expectancy as well as task-value beliefs, while feedback study time was not. In addition, feedback seeking was predicted by student effort invested in the formative assessment. (Contains 2 tables and 1 figure.)