Attention is a construct for which everyone has an intuitive definition. While most of us believe we know what attention is, it is difficult to operationalize. Because it is a process that is so widely distributed throughout the brain, different networks have been proposed to explain the varying types of attention.

In some ways attention and perception are similar. You need to hear, see, or feel a stimulus to attend to it. But we can also pay attention to internal inputs such as thoughts and ideas. One can be distracted by thoughts that continue to intrude on your mind as well as memories that can be summoned by smells or songs on a radio. In this manner, perception and attention become separate but related constructs.

When a ...