Eye Tracking

Eye tracking is the technique of monitoring eye movement while a subject views a document or screen. Eye tracking evaluates specific eye movements and responses such as blinks, pupil dilation, fixations, saccades (a fast move or jerk of the eye) and regressions (right-to-left movements along the line or movements back to previously read lines), which can be indicative of fatigue, cognitive processing, difficulty processing information and areas of interest. Eye tracking is a useful tool in evaluating how people utilise an interface (paper or screen) optimally and efficiently in terms of assimilating information. Displays on paper or screen which are not laid out to exploit human spatial abilities can increase user orientation time drawing mental resources from other tasks and objectives⁶⁶. The efficiency with which a person is able to find and absorb information from a given page also contributes to their satisfaction.

Rayner⁶⁷ in his review of eye tracking of people reading (from paper), explains that saccades (a fast move or jerk of the eye) correlate to about 7-9 letter spaces or characters and about 10-15% of saccades are regressions (right-to-left movements along the line or movements back to previously read lines). Many regressions tend to be only a few letters long and could be due to the reader making too long of a saccade forward, in which case a short saccade to the left may be necessary for reading to proceed efficiently. Short within-word regressive saccades may also be due to problems that the reader has processing the currently fixated word. Longer regressions (more than 10 letter spaces back along the line or to another line) occur because the reader did not understand the text. Rayner also notes that certain types of words such as function and content words impact on fixation time as does word length.

Eye movements are influenced by textual and typographical variables. For example, as text becomes conceptually more difficult, fixation duration increases, saccade length decreases, and the frequency of regressions increases⁵¹,⁶⁸ Factors such as the quality of the print (variations in fonts), line length, and letter spacing influence eye movements⁶⁹. Ponton³⁴ explains that enhancing the usability of an interface (paper or screen) would result in the user fixating less, scanning / reading quickly⁷⁰ and making fewer regressions to previously scanned areas⁶⁷.

The area which has used eye tracking as a means of exploring how people interact with an interface in more depth than any other is in the field of marketing and communications eg newsprint, advertising copy, website design. One of the dominant studies undertaken was the Eyetrack series⁷¹ by The Poynter Institute and its partners. The first, Eyetrack I, (1990-1991) investigated how news consumers interact with print editions of newspapers. Interestingly this investigation broke many myths about how people read newspapers such as “color photos do not automatically draw readers. Content, size, and placement are more important”. Eyetrack II, (1999-2000) reviewed first-generation news websites investigating reading patterns by age and gender. Eyetrack III (2003-2004) undertook further investigation into web design and multimedia components.

In the study of 46 participants in Eyetrack III, several key findings were recorded in reference to review of information onscreen including:

• Dominant headlines most often draw the eye first upon viewing a page, especially when they are in the upper left
• Smaller type encourages focused viewing behaviour (that is, reading the words), while larger type promotes lighter scanning
• Visual breaks, like a line, discouraged people from looking at items beyond the break
• Shorter paragraphs performed better than longer ones.
• People looked at text elements before their eyes landed on an accompanying photo

The Bridge⁷² is a website focussed on marketing and it draws together some findings from eye tracking studies on websites as well:

• Type face - serif upper and lower case - enhances readability and comprehension
• Short paragraphs are more effective over longer paragraphs
• Short words or lines over long words or lines
• Using colour in body copy has a negative impact on readability and comprehension
• In the case of a single page the human eye tracks top left to bottom right
• A colour image is more effective than black and white

Ponton³⁴ in her study for the Defence Science and Technology Organisation on user interaction with Naval combat data systems, used eye tracking as one of the key investigative techniques but as with the Poynter Research and Bridge information and more recent investigations in eye tracking these are largely focussed on human –computer interactions which involve the added complexities of navigation/ search and retrieval of information.

Online versus paper

Although there are several publications which show that people read more slowly onscreen than from paper, they attribute this to the quality of the image presented to the reader. Tinker⁵² reports dramatic interaction effects of image quality variables on paper and according to Gould et al⁷³ (1986) it is likely that these occur on screen too.

Dillon⁷⁴ noted that the reading process is affected by the medium of presentation though they found it extremely difficult to quantify and demonstrate such differences empirically. The major differences appeared to occur in manipulation which seems more awkward with electronic texts and navigation which seems to be more difficult with electronic and particularly hypertexts. Dillon found that eye movement patterns did not seem to be significantly altered by the presentation medium. However he noted that further process issues may emerge as our knowledge and conceptualisation of the reading process improves.

It appears caution should be applied when transferring a successful design for printed documents to the Web. The majority of eye tracking studies are largely devoted to analysis of viewing information onscreen. When Poynter⁷⁵ studied newspaper readers it found that photos and graphics catch the eye first. However when they looked to news websites, they found that users read text before they looked at photos or other graphics. Boiarsky⁷⁶ 2002 conducted an investigation into onscreen readability/useability and noted that additional research needed to be conducted concerning legibility in terms of font size and style and their relation to spacing between letters and words in reading onscreen as there were several contradictory findings between text and onscreen reading.

Therefore we can assume that any recommended format will need to be comprehensively analysed both on paper and on screen and that adjustments in format for the different media may be required.