Predictable and self-initiated visual motion is judged to be slower than computer generated motion

•We compared the perceived speed of self-initiated visual motion and computer motion.•We manipulated strength of action effect contingencies, spatial congruence, and performance by the self or the computer.•Self-initiated movements were judged as slower when action effect contingencies were predictable.•Congruent moves were perceived to be slower than incongruent moves when action effect contingencies were unpredictable.•Self-agency and spatial congruence have separable influences on motion perception.