It’s important in medical product design to understand that users will not always pay attention to visual cues the designer provides. Critical cues must be exagerated or given a treatment that draws attention in an obvious manner. Our eyes are drawn to contrast – both in color and in value (dark vs. light) – and to edges. Supplying a critical control with a bold color that contrasts with the rest of the product will attract the user’s eye and draw attention:
Relative size and the amount of separation between objects also has an effect on how attention is drawn. If you understand these characteristics, you can design visual cues into devices so that users’ attention is guided in a purposeful way. Supplying that guidance is an important aspect of making products intuitive. It allows the user to focus attention selectively and sequentially, which in turn helps the user limit choices and avoid cognitive overload.