One major topic of research in cognitive psychology is how we perceive the world. What processes allow us to take a jumbled set of lines and colors that enter our eye, and transform them into a meaningful representation of the world? Out of features, we build objects, and out of objects, we build categories and classifications for items, objects, plants and people in the world around us. This process is incredibly complex, and much is still unknown about our perceptive capabilities. Besides our perception of the external visual world, we can also perceive objects and scenes in our mind's eye. Mental imagery allows us to remember what we have seen and to work with and manipulate spatial relationships in order to solve certain problems. We will explore the inner workings of mental imagery and its relationship to vision, and examine the process of perception from features to categories.