The design of the displays and controls of a machine can either facilitate interaction or increase task difficulty and the probability of error. General principles for the design of displays and controls exist, but task analysis is normally required before these principles can be applied.
Visual perception - there's more to it than meets the eye.
|1. The perceived figure has form while the background is formless.|
|2. The figure appears to stand out against the background.|
Since the perceptual system is of limited capacity, figure-ground differentiation can be seen as a way of reducing incoming data to manageable proportions. Although information in the figure receives preferential processing at the expense of ground information, the latter is not entirely lost. Ground information provides a context that influences the way the figure is perceived, demonstrating that ground information is processed beyond the physical level. In advertising, journalism and report writing, the use of special typefaces can influence the way a message is interpreted. Italic or bold letters may be used to convey important points.