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Message Display Characteristics and Legibility

Mobiles are used differently from desktops, and even most print use of type. They are closest, perhaps, to signage in that they must be comprehended by all user populations, under the broadest possible range of environmental conditions (e.g., poor lighting) and at a glance. The typical mobile user is working with the device in a highly interruptible man- ner, glancing at the screen for much of the interaction. The message display is competing with millions of other stimuli in the visual field. Therefore, mobiles must be designed to stand out appropriately, beginning with legibility.

The following is a list of legibility guidelines for mobile devices:

Message Display Readability

As we discussed earlier, legibility is determined by how we can detect, discriminate, and identify visual elements. But legibility is not the end to this process of designing effective mobile displays. We must make sure they are readable. When readability is achieved, the user can then evaluate and comprehend the meaning of the display.

Readability is based on the ease and understanding of text. It is determined by whether objects in the display have been seen before. Thus, readability is affected by the message’s choice of words, the sentence structure, appropriate language, and the reading goals of the user (Easterby 1984).

Reading Modes

In September 2004 Punchcut worked with QUALCOMM to develop a typographic strat- egy with respect to its custom user interfaces within its mobile operating system and ap- plications. In that study, Punchcut determined three modes of reading and understanding behavior that occur within the mobile context (Benson 2006).

These modes consider the duration and size of focus for textual attention:




Language Requires Context

These three modes are based within the context of the user’s goals. Just like a user’s goals require context, so does the meaning of language derived from the message’s choice of words. Without context, the intended message display’s meaning may become misunderstood.

In our everyday context, we must derive meaning from others’ intentions, utterances, eye movements, prosody, body language, facial expressions, and changes in lexicon (McGee 2001). When context uses more individual pieces, the less ambiguity we will encounter in the message’s meaning.

In mobile devices today, we may not have all of those contextual aids available to help us derive meaning. The mobile user is presented only with the aids the device’s OS, the technology, or the designer’s intention have provided.

Readability Guidelines for Message Displays

The following guidelines and suggestions should be considered when designing readable mobile displays.


Images as aids

Overflow or truncation

Line length

* Users’ subjective judgments and performance do not always correlate. Studies have shown that users may prefer shorter line lengths, but may actually read faster with longer lines.

Next: Typefaces for Screen Display

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