Ericsson et al (1993) found that improvement in performance was evident when individuals were given tasks with well-defined goals and were provided feedback by their teacher. There was also ample opportunity for repetition. Full concentration is required. Ericsson calls this deliberate practice. Deliberate practice is above that of playful engagement, and these two types of practice do lead to differences in the level of performance obtained. A study completed on violinists showed that those who used deliberate practice (solitary practice) in music rather than an array of music-related activities, achieved higher levels of performance. Even when the students had all studied 10 or more years on their instruments, those with the most solitary deliberate practice hours were the highest achievers.