Q. Concentration of mental effort?

Attention can be defined as "the concentration of mental effort on sensory or mental events.

There are three types of attention selective attention, sustained attention and divided attention.

Selective or Focused attention refers to the capacity to perform a task in the presence of distracting stimuli. The capacity to listen to conversation at a railway station, identify a friend in crowd.

Sustained attention requires ‘holding' attention over relatively long periods of time. The capacity to study or the capacity to listen to a lecture for an extended length of time is an example of sustained attention.

Divided attention refers to the ability to perform or attend to two or more tasks simultaneously. The concept of divided attention explains dual tasking, wherein two tasks require effort and attention. For example a subject may be presented with stimuli which vary with respect to color and motion and monitor changes in both the dimensions.