The most difficult thing for him, he says, is the concentration required.

And he could not watch where she was going; his steps required too much concentration.

Almost possible, save that each new task took longer and required more concentration.

It would require intense effort and concentration on the part of everyone involved.

It can be used only once per operation and requires great mental concentration.

Most important, the plan leaves out the fact that cooking requires concentration.

He didn't make mistakes, but each stroke required serious concentration.

She decided music might require less concentration, permitting her to check in and out.

The job, which pays $105 a month, requires intense concentration.

Because the dance requires little physical concentration, participants often talk to each other while dancing.