This paper examines the competences exerting the greatest influence over interpreting performance in a sight translation exercise. The effect of three components of interpreting competence (anxiety control, short-term memory and speed of oral reflexes) on performance are tested in a sample of 22 subjects. The results obtained suggest that only speed of oral reflexes influences performance. Comparative analysis reveals, however, that subjects with low scores in all three components perform less well than subjects with average or high scores. The implications for identification of component skills of interpreter competence are discussed.