There are two different pathways in the brain that control different functions of what is known inclusively as the visuo-spatial sketchpad. The sketchpad consists of the spatial short-term memory and the object memory. The spatial short-term memory is how one is able to learn and thus remember "where" they are in comparative representation to other objects. The object memory of the visuo-spatial sketchpad is essential in learning and remembering "what" an object is. The differences between these two differing visual abilities is due in large part because of different pathways of each of the abilities in the brain. The visual pathway in the brain that detects spatial representation of a person to and within their environment is the dorsal stream. The visual pathway that determines objects shapes, sizes, colors and other definitive characteristics is called the ventral stream. Each of these two streams runs independent of one another so that the visual system may process one without the other (like in brain damage for instance) or both simultaneously. The two streams do not depend on one another, so if one is functioning manipulatively, the other can still send its information through.