S. Krashen, April 2015
Csikszentmihalyi, Rathunde, and Whalen (1993) monitored concentration among "talented" teenagers (grades 9 and 10 in accelerated classes and nominated by teachers) and comparison teenagers while doing various activities by interrupting them with electronic pagers and asking them various questions (p. 52-53), including "How well were you concentrating?"
They found that talented teens did not study more, did not read more, and in fact watched significantly more TV than others (page 87), but their levels of concentration were different: "Talented students reported relatively higher levels of concentration than their average peers when invovlved in classwork, studying, reading, and sports and games. But in less demanding activities, such as household chores, socializing and watching TV, their concentration levels dropped well below those of average students" (p. 97).
Apparently, they knew when to concentrate and when to relax. Relaxation may have real value, promoting the emergence of new ideas and solutions to problems (Krashen, 2001).
Csikszentmihalyi, Rathunde, and Whalen (1993) Talented Teenagers: The Roots of Success and Failure. Cambridge: Cambridge University Press.
Krashen, S. 2001. Incubation: A neglected aspect of the writing process. ESL Journal 4(2): 10-11. (Available at: http://sdkrashen.com/articles.php?cat=3)