Discriminability for conspicuity and comprehension
If you can’t see information, there is no information. Depending on a given scenario, people do not take up information in the environment like they read a book. If looking for clues on how to find the way, or how to orientate, we visually search by glancing. As soon as a clue to follow is found (for instance a sign of distinct shape and colour) we switch to scanning, since we now know what to look for. For glancing and scanning, information needs to be conspicuous to be noticed.
When looking for e.g. a destination name on a signboard, we scan, too. Skimming the text, we only stop when we find the piece of text or symbol we look for to find additional clues. This time, the information must be discriminable in order to allow for a largest possible variety and number of people, under a variety of visual (and other) impairments, stress, time restraints and environmental conditions to work.
When actually reading a text sign (almost) the way we do in a book, discriminability (= legibility, if relating to text) is essential, too. The same requirements as above apply, except for time and stress, which could be considered here as less influential.

Design and Calculation
The MOA Design Method relies on two interacting concepts to enhance information efficiency-
- “SGD Design” principles, and
- “MOA Math” calculations.

.