attention span
noun/əˈtɛn.ʃən spæn/
1
The length of time, or span that one can pay attention, or concentrate on one topic without becoming distracted.
- He has learning difficulties because of his short attention span.
- Limit your training sessions to fifteen minutes; twice each day. One half-hour session is not recommended as a rock's attention span is rather short. Remember; a bored rock is an unhappy rock.1975, Gary Dahl, The care and training of your PET ROCK: