To handle or manage bulk amount of information coming from environment, human beings require a selective focus (attention) to certain amount of information as the short term store of memory is limited for a human. Therefore, attention is important to choose information of interest and for managing huge amount of information. In general, attention is normally discussed in terms of visual and auditory senses. Wickens (1992) classified attention into three categories viz. selective attention, focused attention and divided attention.

Selective attention- “Selection is the choice of what to pay attention to. An error in selective attention is the unwise deliberate choice to pay attention to an environment source of information that is less than optimal for the task at hand.”

Selective attention may occur due to tunnel vision that makes us less open to alternative options.

Focused attention- “Focus in attention is the ability to withstand distractions. Failure to maintain focus results in the intrusion of external environmental information in spite of an individual’s efforts to shut it out.” In this context, it may be reasonable to state that focused attention can be diverted easily by emotionally charged stimulus and our focus may be directed to this emotional stimulus.

Divided attention- Divided attention is attention that is required by more than one activity at the same time.” People often experience problems when attempting to divide attention between two or more sources of information. In such situation, what we are doing is quickly sifting our attention between tasks rather than working on these tasks simultaneously.

Supervisory control tasks such as piloting an aircraft or air trafficking focus on optimizing selective attention. These tasks are done by dividing the whole work environment into different channels and monitoring the channels for critical events that may expected to occur.