Everyone procrastinates sometimes, but 20 percent of people chronically avoid difficult tasks and deliberately look for distractions—which, unfortunately, are increasingly available. Procrastination in large part reflects our perennial struggle with self-control as well as our inability to accurately predict how we'll feel tomorrow, or the next day.
Quite simply, cognition refers to thinking. There are the obvious applications of conscious reasoning—doing taxes, playing chess, deconstructing Macbeth—but thought takes many subtler forms, such as interpreting sensory input, guiding physical actions, and empathizing with others. The old metaphor for human cognition was the computer—a logical information-processing machine.