The Eyes Have It!
Some scientific tidbits about how your eyes work, and how your brain processes the information

How Our Eyes Read

• When we read, our eyes do not move smoothly across a page. Instead, they focus on one word or a group of words in a process known as fixation.
• After each fixation, our eye moves to the next grouping in a movement called a saccade. This pattern is repeated several times before we pause to comprehend the phrase we just read.
• Occasionally, we will experience a regression, which is a slight movement of the eye backwards on a line of text. This occurs when we are having trouble comprehending the material.
• At the end of a line, our eyes perform a return sweep, which repositions our gaze at the beginning of the next line.

Why is it more difficult to read on a computer screen?

• On average, people read electronic text 25% slower than print text.
• Many people report eye strain and other discomfort when reading off a computer monitor. The amount of light emitted from the monitor is the cause of this strain.
• Reading is also hindered by the number of pixels in a monitor. For ideal reading, 300 pixels are needed; however, most monitors contain 72 to 100 pixels. In order for comfortable reading where words appear as smooth as they do on a printed page, screen resolution needs to be improved.
• Taking notes while reading electronic text is also a problem. For paper text, you can take notes directly on the page. For electronic text, you need either a separate piece of paper, a separate screen, or a separate window to keep track of your comments. This, in combination with the uncomfortable reading position, often results in more fidgeting, which can slow down reading time.
• In most printed books, line length usually measures between 5 and 6 inches. Most newspapers average 3 inches. Line lengths are generally kept short because it has been shown that narrower lines are easier to read: the longer the line, and the more saccades required to complete the line, the more difficult the return sweep.
• Many electronic sites format text into 10 or 12 inch lines, spanning the entire screen and making them more difficult to read.
• Studies have shown that narrower paragraphs on computer screens can be read slightly faster than longer ones. Making return sweeps in wide paragraphs was also shown to be more difficult and required more effort to reposition gaze at the beginning of a new line. The same studies also reveal that long lines of text cause the eye to make more regressions per line, significantly slowing down reading time. The longer line length caused the eye to make more tracking mistakes, requiring re-reading.
• Other experiments revealed that narrower paragraphs resulted in a better retention of information, despite the fact that those reading narrow paragraphs completed their reading more quickly. This indicated that the extra time required to read the wide texts was spent re-orienting fixation, not processing the material.