Lecture Notes in Computer Science- P99 ppt

Studies on Human Computer Interface Design of Chinese Mobile Phone Users 479 We briefly present below researches from our lab investigating font size and dif- ferent pairings of font and background color on Chinese users’ ability to effectively read messages and navigate a cell phone interface. The studies presented here were based on mobile phones with Chinese interface, and these studies were more relevant with the mobile phone communication and other functions as message sending, web exploring and learning functions. However, these studies also had significant implica- tions on the other mobile devices designing, and the mobile e-learning devices such the Pocket or Palm PC, e-dictionary and the other learning device designed for the primary and middle school students. We do hope these researches could lead further studies in the mobile interface and help the mobile e-learning device designing, so make the e-learning interface to be operated more efficient and freely. 2 The Effects of Background and Font Color on Chinese Text Presentation This present study was intended to research color matching of font and background, which was more important for the cognitive science researchers interested in HCI and the media interface designers, as high efficient font and background color matching can improve user operating efficiency, and reduce optical fatigue (Fang, 1998; Fang, Wu, & Ma, 1998)[17,18]. When designing visual computer interfaces, most designers select their matching colors according to their subjective sense or experience, without specific theoretical or experimental and practical support. The theory of optics can provide some theoreti- cal support for color matching of the interface. The interface designers can work on the principle of maximizing the difference in brightness between the background color and two or more dominant fonts (Zheng, 2000)[19]. Some other study (Xu et al., 1997a,1997b)[20,21] also did the further experiment by the subjective colors rating in the user interfaces, and the studies by Hua, Gong, & Zhao (2001)[22] showed that color matching for cathode ray tube (CRT) displayer could be generalized to liquid crystal displayer (LCD). In order to design an efficient interface using high efficient color matching, the researchers should do some further studies on human color vision and personal preferences to support the user interface design. The following was our study on font and background color matching. In this study, the RGB color function, its color parameters of background and font color matching were shown in Table.1. In this study, computer was used extensively for reading text, and high efficient color matching might be expected to enhance reading comprehension speed. Rapid serial vision presentation (RSVP) was used in the study, which was a method of dis- playing letters, words or pictures one after another in a specific visual field. Xu and Zhu (1997a; 1997b)[20,21] used this method with a fixed-rate moving windows to study the key factors which influenced Chinese text reading comprehension. Shen, Chen, and Tao (2001)[23] studied the effects of scrolling, leading (in which the text scrolls from right to left on a single line) and RSVP on reading comprehension. These studies were, more concerned with the issues of presenting Chinese text, however, they did little studies on font and background color matching, which the present study have done and reported. 480 X M. Zhang, Y N. Li, and F.C. Blumberg Table 1. The background and font color matching and its RGB parameters Background color Font color Black 0㧘0㧘0 White Red Gray Deep green Purple 255㧘255㧘255 255㧘0㧘0 128㧘128㧘128 0㧘128㧘0 128㧘0㧘255 White 255㧘255㧘255 Black Red Gray Deep green Deep blue 0㧘0㧘0 255㧘0㧘0 128㧘128㧘128 0㧘128㧘00㧘0㧘255 Blue 0㧘0㧘66 White Red Yellow Deep green purple 255㧘255㧘255 255㧘0㧘0 255㧘255㧘00㧘128㧘0 128㧘0㧘255 Fig. 1. Average reading time (sec, second) for different color matching pairs This study was designed to measure the effect of font and background color matching on the participants’ reading efficiency (the indictor was reading reaction time), subjective sense of fatigue, and their personal preference for color matching. A moving window paradigm was used. Participants were required to send short mes- sages. The reading time for the fifteen font and background color matching was shown in Fig.1. According to the results, reading time was shortest with a black font on a white background, and longest with a red font on a black background. The background-font color pairings white-black, white-deep blue, blue-yellow, blue-white and white-deep green had shorter reading reaction time than black-white, white-red, black-deep green and black-purple. Based on these findings and participants’ reports of optical fatigue, we can use the result of fig.2. to design the user interface, which the best choice of font and background were white-black, white-deep blue, blue yellow and blue white, avoiding to use black-deep green, black-white, white-red and black-red. Studies on Human Computer Interface Design of Chinese Mobile Phone Users 481 3 Message Reading Efficiency on Color Screen Mobile Phones As LCD technology has developed, color screen mobile phones are increasingly pre- ferred by users, and are gradually replacing black-and-white mobile phones. Like their black-and-white counterparts, color screen phones use whole-page or whole-line scrolling. One question concerns whether the scrolling style (whole-page, scrolling by line, or scrolling up and down) and screen background (whether there was a back- ground picture) affects reading speed and comprehension. For this study, we used a software Nokia mobile phone simulator with fixed brightness and contrast ration, and a standard mobile phone keyboard, display and operating system. The simulator’s display was 100 pixels wide and 90 pixels high, the illumination level was 130 lux, and there was 30-50 cm between the participants and the display. Participants were required to read 48 messages of different themes, and then an- swer 3 multiple choice questions, each with 3 possible answers. Each message was about 50 Chinese characters long. There were 3 reading styles (one-page-at-a-time, one-line-at-a-time, and constant scrolling) and 2 background styles (background with or without picture). Accuracy was measured by the number of correct responses to questions. For the sample presented, the mean accuracy was 89%, and each message was read in less than 60 seconds. The variable of interest was the reading time. Across background conditions (picture or no picture), there was a significant effect of reading style as the one-page-at-a-time style resulted in significant reduction in reading time than one-line-at-a-time or constant scrolling, in accordance with Laarni’s conclusions (2002,2004)[10,24]. Across reading styles, there was a significant difference between the picture and non-picture background conditions. The presence of the picture reduced reading time in the one-line-at-a-time reading style, and increased it in the one-page-at-a-time style. No significant differences were found involving the constant scrolling style. It was clear that in the one-line-at-a-time reading style, reading speed is enhanced by the presentation of a background picture. The main reason for this finding is likely that the picture supplies background and spatial cues, making it easier for users to focus their attention on reading the messages, particularly when the content of those messages are presented one-line-at-a-time. In the constant scrolling reading style, there was no significant difference between picture and no picture background. In this reading style, the user has to control the movement of the message by repeatedly pressing a key, and users may get lost, resulting in decreased reading efficiency. In the one-page-at-a-time reading style, reading efficiency was better when there was no background picture. In this style, the users scroll fewer pages and switch lines less frequently, and therefore was not probable to get lost where they were reading. Since there was no message movement, the background picture might interfere with the way the message was perceived. Although the picture was the same, participants might have treated it as a new stimulus, taxing their working memory and thereby demonstrated weaker reading efficiency. In situations when there was no background picture, there was no significant dif- ference between the reading speed in the one-line-at-a-time and constant scrolling 482 X M. Zhang, Y N. Li, and F.C. Blumberg reading styles; however, message reading in the two styles were both significantly less efficient than that in the one-page-at-a-time reading style. The main reason for the similarity of the first two styles is the similar operation, frequent line breaks, and lack of spatial cues, with constant refocusing of attention on the relevant part of the message (Melchior, 2001). In fact, some correlative work on eye movement (Piolat, 1997; Baccino & Pynte, 1994)[25,26] has shown that spatial cues do in fact, contrib- ute to better reading efficiency. However, because participants were unable to forecast successive parts of the message in both reading styles, and may have got lost (Mel- chior, 2001)[11], a reduction in reading efficiency was found as compared to the read- ing style of one-page-at-a-time. When there was a background, the one-line-at-a-time and constant scrolling styles yielded significantly better reading efficiency than the one-page-at-a-time reading style. 4 Menu Style of the Mobile Phone Interface on Operation Efficiency In a well-designed menu pattern, the process of operation should be identical to that of human cognition so as to make the information exchange fluently (Lee, Whalen, McEwen & La-tremouille,1984)[27]. In the perspective of psychology, excellent user interface (UI) should follow the principle that “the operation should be identical to human behavior habits and cognition” (Liu & Shen,2000; Melchior, 2001) [28]. For instance, the process of visual search is an important part of menu selection, which includes two possibilities: parallel or serial selection. The present study considered three most common UI design patters (matrix pattern, tree pattern and page-to-page pattern). It was commonly considered that matrix pat- tern was the most convenient design because it contains two dimensions whereas the other two patterns contain only one. However, two-dimensioned menu will take more space of the display, especially when the options are of big number. Some researchers (Hopkins et al.) suggested categorizing the menu options against the logic, but their suggestion had not been justified (Shieh, Hsu, & Liu, 2005; Zhang, et al.; 2004; Zhang, et al., 2006)[12,14,29]. The present study was not only a complement to the Hopkins’ theory, but also an experimental study to give support to his theory. More- over, research by Zhang et al. (2004) on the ergonomics of the menu-display effects of the mobile UI suggested that there was no significant difference between the users’ responses to the size of the icons and the size of the characters in all levels. Based on related researches (Laarni, 2002; Melchior, 2001; Shieh, Hsu, & Liu, 2005; Laarni, Simola, Kojo, & Risto, 2004; Zhang, et al., 2006)[10,11,24,29] and some other stud- ies[20,31,32], the present study on the UI operation tended to investigate the follow- ing questions: (1) the effect of the menu-display patterns on the efficiency of the operation; (2) the effect of the logical categorization of function options on the effi- ciency of the operation (totally logical categorization and non- totally logical catego- rization); (3) user’s preference to the menu designing patterns. The result of the operating efficiency between different patterns was significant: the matrix pattern condition yielded the best efficiency, then the tree pattern, and the Studies on Human Computer Interface Design of Chinese Mobile Phone Users 483 page-to-page pattern yielded the worst, which was in the accordance to the hypothe- sis. The reason why the matrix pattern yielded the best efficiency was that the dis- tance between options was shorter than that of linear menu, and the users could switch from one option to another more easily. Furthermore, the operation of matrix pattern depended on navigation by cognition not by memory and therefore the users would not get lost. The reversibility in operation was one of the reasons, too. Besides, the matrix pattern had a larger capacity for information so that the users could get more information without scrolling pages. The results showed that the operating efficiency was better in totally logical cate- gorization. The reason was probably that the totally logical categorization could save the users cognitive load in their operation process than non- totally logical categoriza- tion. Moreover, the operating efficiency of deeper and narrower menus was better than that of shallower and broader ones. Therefore, the designers should pay more attention on the depth and breadth when designing mobile phone menus. Generally, users preferred menu patterns in which the RT was shorter to those in which the RT was longer, and it was the case for the logical categorization. The re- sults gave further evidence that the matrix pattern and totally logical categorization could help users to operate the phones more effectively, which provided suggestions to designers on how to design small interfaces with efficiency, individualization and powerful functions. 5 Conclusion Collectively, the series studies reported in present paper were generally based on the mobile phone interface, and the main questions we concerned were the operating effi- ciency of the simulated mobile phone and the efficiency of message reading in different font and background based on the computer interface. These studies have important implications on interface design of the mobile e-learning devices, the findings of the studies from our lab may generalize from mobile phone message reading to other cir- cumstances where there is a small screen interface, such as mobile web interfaces, the PAD mobile phone, pocket or palm PC, GPS device, electronic dictionaries and other mobile e-learning devices designed for the primary and middle school students. With the advent of increasing forms of technology incorporating small screen in- terfaces both in China and other countries of the world, consideration of how best to design these interfaces will remain an issue. We will do some further studies on this topic, collect more data to support the mobile e-learning devices interface design and help the designer produce more efficient operating interface for the more and more e- based learners. Authors’ Note and Acknowledgements The present paper was supported by 2007-2008 grant of the Beijing Key Lab Project (Beijing Key Lab of Applied Experimental Psychology). The authors wish to extend their thanks to Lan Xue-Zhao, Lu Tian, Guo Xia-Mei, Zhang Ya-Zi, Ran Tian, Sui Yi, and He Li. . reduced reading time in the one-line-at-a-time reading style, and increased it in the one-page-at-a-time style. No significant differences were found involving the constant scrolling style advent of increasing forms of technology incorporating small screen in- terfaces both in China and other countries of the world, consideration of how best to design these interfaces will remain an. fixed-rate moving windows to study the key factors which influenced Chinese text reading comprehension. Shen, Chen, and Tao (2001)[23] studied the effects of scrolling, leading (in which the