Readers are influenced by the following in online documents:

Verbal,

Visual, and

Sound

While you may decide to use features of your own, or choose to ignore what research has shown about on-line documents, you should be familiar with this knowledge.

If you choose to ignore such results, you should be aware that you are doing so, and be prepared to justify the deviation.

There are also conflicting solutions for on-line presentation. For example, it is well known that:

Users do not like to scroll

Users like be able to find what they are looking for within a few mouse clicks

Users like lots of white space on a screen to be able to concentrate on the words

It may be difficult to create a presentation which satsifies all of these.

Screens vary and are limited by

Size,

Resolution, and

Color Quality

Research has shown that:

People read only 75% as fast on a screen as they do on paper

People like each screen to be in the same format. (e.g., return button on the left)

Readers prefer pictures to words

Readers like audio - spoken words - for narration or instruction

Readers like animation to show continuous change or motion

Users like to be able to control speed and links

Such research suggests the following guidelines should generally be followed

Lines should have a maximum of 60 characters

At any one time, less than 50% of the screen should contain characters - the rest should be clear - "whitespace"

Paragraphs should be short - 3 to 6 lines and separated by blank lines

Using the same format (e.g., picture on the left, writing on the right, buttons on the bottom) help to increase reader comfort.

Bold, italics, color and flashing help highlight, but should not be overused

Scrolling should be limited if used at all.

Color

In books, color is sometimes used to be decorative.

With today's screen resolutions and other aspects, color should not be used as a decoration on the screen.

It should be purely functional. According to Horton:

Color helps users to isolate and separate various items on the screen

Color helps users to focus their attention on information.

Color helps users find these faster

Like other aspects of multimedia, color preferences are an individual matter.

Research has shown, however, that:

Few colors should be used - a maximum of 3 or 4

Colors should be distinct - avoid similar colors

Avoid garish colors - pinks, purples and pastels

Use colors that have meaning - like red for danger, green for safety, blue for water related items etc.

Gray has been found to be the best background color

People read colored text more slowly than black and white.

In any case, use black or a primary color for text

Legibility tests have found that:

On a white background, use blue, black or red and avoid yellow and cyan

On a black background, use white, yellow or green, and avoid blue, red and magenta

Other factors to consider for color are the differences between displays. Colors vary in the way they are projected.