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An international peer-reviewed journal

Improving the Usability of E-Book Readers

Eva Siegenthaler, Pascal Wurtz, Rudolf Groner

Journal of Usability Studies, Volume 6, Issue 1, November 2010, pp. 25 - 38

Article Contents


Our study shows that the legibility of the current e-reader generation is comparable to that of classic paper books. E-ink technology enables a reading process that is very similar to the reading process of classic paper books. In our experiment, participants had the possibility of choosing the font size they liked. We have identified that especially older people prefer a big font size, and the eye-tracking data show that participants had significant shorter fixations on the e-readers compared to the classic paper book, which is an indication for better legibility. As a conclusion, we can say that in some situations, e-readers, with the option of changing font size, can have better legibility than classic paper books. The option of adjusting the font size could also enlarge the user group. For instance, people with low vision may benefit from the possibility of increasing font size on e-readers.

It should also be mentioned that the fact that participants had the possibility to adjust font size probably influenced eye-movement data. Because reading distance was constant and font size in the classic paper book was very small, some participants (especially older participants) reported problems with reading. This may have contributed to longer fixations in the classic book. Smaller font size may also be related to the number of letters per fixations. A single fixation covers more letters when the font size is smaller. One of the disadvantages when reading on an e-reader is the time spent with page-turns. Page-turns take a longer time with current e-ink technology because the building up of the displays takes some seconds. Another reason for the time loss due to page turning is the larger font size. Increasing font size inevitably results in a higher number of pages and, as a consequence, more page-turns. Although larger font size can negatively affect some eye-movement parameters, the possibility of adjusting font size will lead to better usability and also to better legibility.

The results of this study showed a remarkable deficit in the usability of the current e-reader generation. Participants had great problems using the e-readers. This is a crucial problem because perceived usability can influence subjective legibility ratings. In other words, if a person is not able to use a reading device efficiently, then he or she does not like reading with it. Future e-reader generations should have a more intuitive design. Users expect more from such a device than only displaying text. Further, e-reader generations may incorporate additional functionality like wireless local area network (WLAN) compatibility, the possibility to highlight text sections, a comment function, or a fast search function. To integrate such functions and make them intuitively usable will be a challenge for e-reader developers.

The finding that the usability of a device has an effect on legibility judgments expresses a methodical problem. In the first legibility test, where participants had no experience with the e-reading devices, the participants’ acceptance ratings were in close agreement with the efficiency of their eye-movement data. Thus, participants were able to judge which device was best for reading. However, after a period of self-regulated handling of the device, during the second legibility test, eye-movement data and the interview data showed a discrepancy. Between the first legibility test and the second legibility test, the participants had the opportunity to use the devices and had to give their usability ratings. In this session, participants encountered several problems during the interaction with the respective reading devices. They became disappointed or frustrated when they were not able to perform the exercises successfully. This outcome influenced their judgments in the second test session. After the second test session, the participants judged the classic paper book with the highest legibility rating. Objective eye-movement data remained constant, because eye-movement behavior is predominantly controlled by automatic and unconscious processes, which are not likely to be changed or manipulated deliberately and are only partially accessible to awareness (Albert & Tedesco, 2010). This discrepancy between subjective rating data and objective performance measures is an important cue for the interpretation of the results; it shows that the usability of a reading device is at least as important as its legibility.

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