6.1.2-5 Overall Assessment at a Glance

The manner in which information is presented in the overview display should provide a characterization of the situation as a whole in a concise form that can be recognized at a glance.

Additional Information:
Rapid assessment of plant conditions requires personnel to quickly extract status information from the display. Rapid assessment is determined by both the amount of information and the manner in which it is presented. That is, presentation techniques may be used to reduce demands on the user's attention while maintaining the quantity of information contained in the display. The following design techniques are particularly relevant to the design of overview displays for supporting rapid overall assessment of plant condition: (1) Coding schemes should be used to make important information the most perceptually salient. (2) Related concepts should be spatially grouped and information should be imbedded within graphical objects to reduce the need for shifts in attention caused by excessive eye movement. For example, organize data by plant safety function; incorporate bar charts and digital values within symbols for major plant components. (3) The number of objects presented should be minimized to reduce demands on short term memory. (4) Cues that support rapid access to long-term memory stores, such as well defined object categorization schemes and pattern-matching cues, should be used to reduce demands on attention. (5) Information processing such as filtering, suppression, and prioritization, based on considerations such as plant state and operator task requirements, should be used where the quantity of incoming information may impose excessive demands on operators. (6) Display formats that make use of peripheral vision capabilities should only be used to facilitate non- attentive monitoring of qualitative changes of less important information and should only be implemented where they do not detract from primary task performance.