Attention is the capacity to select and maintain awareness of an exterior event or a thought. It corresponds to the general waking state and to vigilance, which lets the nervous system be receptive to any form of information that comes to mind.
Attention disorders affect children and adults who cannot sufficiently concentrate on work to be done over long periods, even if this work requires only a minimum of intellectual effort or has a routine or familiar character to it (such as revising or recopying).
A specific modality of attention is the capacity to divide one’s attention among several sources of information or tasks to be done. A deficiency in this attentional modality is not only very costly in a cognitive sense, but is also a source of difficulty and even considerable suffering for a child in a school setting.