A perceptually distinct reference aid should be provided in a configural display to support operators in recognizing abnormalities in emergent features.
Additional Information:
When a change in an object's characteristics (e.g., its shape) is the perceptual feature that indicates a fault or abnormal condition, perceptual cues can assist operators in detecting the change. If shape is used, the display graphic should include the normal reference point against which operators can compare the current one. Reference points are especially useful when the abnormality is slow to evolve, and the integral object is slowly changing. Recognition of abnormalities can also be aiding by having normal conditions represented by regular, symmetrical shapes and abnormal conditions indicated by asymmetrical shapes.