Imagine the smell of freshly brewed coffee. Imagine the taste of salty potato chips. Imagine the feeling of sandpaper on your fingertips. Imaging the feeling of standing on one foot. Imagine the opening bars of Beethoven's 5 th symphony.
Imagery seems to play useful roles in cognition.
For example, people report using visual mental images to perform certain kinds of cognitive tasks. In the 19 th century, David Hume argued that all thoughts are images. This view was adopted by many introspectionists, who thought that we should study psychology by introspecting images. Shortly thereafter, Watson argued imagery is not a proper subject of scientific psychology. When cognitive science emerged, imagery was largely ignored in favor of cognitive phenomena like reasoning, problem solving, memory search, etc.