A discussion is provided of the ways in which physical aspects of vision affect the way information is processed by people, including the importance of decision-making. Human visual perception is the ability to see light, which is either emitted by objects or reflected off the surfaces of objects. Light that shines on the fovea is seen in very fine detail, while visual stimuli detected by parts of the retina other than the fovea are much less detailed, but able to concurrently process large amounts of information throughout the span of vision. The eyes sense visual stimuli, and the brain perceives the data to make sense of it. Sense-making is a function of short-term memory. In graph design, for instance, all lines cannot be kept all at once in short-term memory. Therefore, the number of data components that encode separate meanings should be kept to seven or under, with five the optimal maximum. A list of the described pre-attentive attributes that are of special use in visual displays of data are form orientation, line length, line width, size, shape, curvature, added marks, and enclosure, color intensity and hue, and 2D elements for spatial position. Although attributes that cannot be perceived quantitatively in graphs can still be used, their use should be restricted to distinguishing categorical differences. Visual displays that have much data are not only a suitable and correct complement to human abilities, but such designs are often optimal.