Effects of background colors on user's experience in reading website

Transcription

1 Effects of background colors on user's experience in reading website - KIRITANI Yoshie*, SHIRAI Shogo** *Chiba University, Dept. of Design & Architecture, 1-33 Yayoicho Inageku Chiba JAPAN, kiritani@faculty.chiba-u.jp ** Nippon Timeshare Co., Ltd, e-application Dept., Enterprise Solution Div., Mita, Minatoku, Tokyo JAPAN, shogo001@mac.com Abstract: The present study focuses on effects of background colors of the website on users, considering experience design. Recently user-oriented design has called attention, and experience design was emerged; it involves giving meaningful experience to user by a penetrate approach in any kinds of design. We consider the experience design as design giving user beneficial period, because "experience" is not a static point but process developing in the course of time. The experience design should create products or service integrated in as time passes, to produce user's experience. Thus, we pay attention to human time evaluation. It is important, for the design of websites, to know how the user spends time during reading of website. We decided to treat the color of the background of site, because the small but important change would be brought into the website design. In the experiment 1, 5 colors, white, red, green, blue, and yellow were examined. Fifty subjects had to search information about certain topics in actual directory reference. During the task, the subjects had also to respond to the beep sound, which was a check of subject's attention paid to the task. After the task, the subjects evaluated the time spent for the task and some impressions like devotion and fatigue. The results showed that white, blue and green background made the subject felt time longer, while red and yellow background brought less overestimation of time. Moreover, the background led bigger time error brought smaller irritation, fatigue, and also weaker impression of achievement to the reader of sites. The Experiment 2 contained 2 tasks, visual searching and understanding of contents, which are considered as two main aspects of reading sites. No effect of background colors on time evaluation was seen in the task of visual searching and understanding of contents. But white background made the subjects devoted in visual searching task. The reading of sites was less fatigued than the visual searching and the understanding of contents. Thus, the reduction of task into sub-tasks, an operation necessary for the psychological experiment, is to be done carefully. In conclusion, we can change the user's time evaluation during reading of websites, varying the background colors of the sites. Cold colors can bring the users quiet, not active nor vigorous, time in reading websites. Key words: time evaluation, background color, reading of websites, user experience 1. Introduction Thanks to the information and communications technology (IT), information and communications services penetrate into our daily life. IT has a significant impact on our lives, society, and even our ways of thinking. Now, we can get information whenever and wherever we want it: the arrival of ubiquitous society. White paper of Ministry of Public Management, Home Affairs, Posts and Telecommunications [1] reports how penetrates the Internet in Japan. The number of Internet users at the end of 2001 was million (an 18.8%

2 increase over the previous year), and the penetration rate in the population as a whole was 44.0% (a 6.9 point increase over the previous year). This rate ranked 16th in the world. The number of Internet users in Japan has been rapidly on the rise over the past few years. In a survey on the need for the Internet in everyday life two out of three Internet users felt that the Internet was absolute must in everyday life. As purpose of the Internet, the use of ranks (96.4%) as number one, magazines (76.3%) and the gathering and searching for information (70.0%) have also become popular reasons for making use of the Internet. Over 70% of teenagers use the Internet, 68.5% of twenties, 68.4% of thirties, 59.0% of forties, 36.8% of fifties, and 15.9% of sixties. We cannot deny economic benefits brought by the Internet, although "net bubble" is a worry. To gather customers, the management side cannot ignore the use of any kind of Internet services. If the ubiquitous societies not so mature, the management side may easily satisfy their customers giving high quality service via Internet. However, another extra services besides enrichment of the contents of websites will be soon needed. User-oriented design has been a recent center topic in the design field. When the designers design something, they pay attention to user's properties not only physical but also psychological. Universal design, barrier-free design, usability, accessibility, user experience are typical concepts of user-oriented design. Their purpose can be summarized that people comfortably and easily uses products or services. We should consider user-oriented design also in the Internet. The present study picked up the experience design in the Internet. In fact, this term originally used in the webinteraction design to give users active participation; the users feel controlling, by themselves, the progress of events on the computer monitor. This concept has diffused into other area of product design. In the experience design, the users have consist and meaningful experience using the products or the service. This is somehow upper concept of the usability or the accessibility, which has been considered concerning the interface in the web design [2, 3, 4, and 5]. In the present study, the experience design in the Internet was considered in view of human time evaluation. The experience is not a moment, a static point, in the time course, but a process. It would be useful to know how the users spend time in reading websites. To give more comfortable Internet life to the users, but with a small amount of effort of the manager side, we would like to examine more suitable background color of the website considering human time evaluation. There are a lot of psychological researches about time, which can be divided into 2 categories according to their research object: time perception and time evaluation. Time perception refers to rather short duration like psychological present. The perception of longer duration is called as time evaluation, because it is not mere perception but includes judgment and/or memory. Time perception involves psychological unit of time like the instant, while time evaluation covers longer time duration that is not a spot but course intervened by so-called higher cognitive process [6]. Time estimation is influenced by the subject s current circumstance and cognitive factors. Mead (1959) [7] revealed that the subject motivated by tasks evaluates time shorter than non-motivated subject does. Fujiwara and Kano (1994) [8] examined time estimation during VDT operation with a hypothesis that the clear working goal and real-time feedback of working results motivate the person and lead to higher performance and underestimate of the working duration. The hypothesis was verified with an interesting finding that the subjects did not realize the time reduction. The present study picked up and showed properties of the time evaluation during website reading

3 2. Preliminary experiments The questionnaire was filled out by 146 undergraduate students to know the current use of internet by young people. One hundred homepages of the company and 100 private homepages were also checked to know which color was used in the background of their homepages. As results, we decided to use students who mostly have an experience of the Internet as the subjects and to select 5 representative background colors, white, red, green, blue and yellow, as stimuli, from over 16 million colors. Time span of an experimental session was decided as follows. The results of the questionnaire showed that most students spent 10 minutes for the Internet. But, this value, "10", seems to be rounded and does not reflect real state. Thus, using the same three tasks as in the experiment 1, 8, 10 and 12 minutes of the experimental session were examined; there were no significant difference among these three values. In the main experiments, the duration of an experimental session was 8 minutes for consideration of the subject's fatigue. In the main experiments, the response to a beep sound was also measured to know subject's concentration to the task. If the subjects deeply concentrate on the experimental task, they cannot respond not so quickly to the sound. But, when there are so many inserted sounds, they may disturb subject's performance to the main task. From the examination of three intervals for inserting of beep sounds, 30, 60, and 90 seconds, 90 seconds was used in the main experiments. 3. Experiment 1 The purpose was to examine effects of background colors of the website on users in reading sites. 3.1 Method Subjects Fifty undergraduate and graduate students participated in this experiment. All subjects used the Internet at least once a week Apparatus and stimuli The website as stimulus was presented on the 21-inch CRT display (Radius Press View21SR) controlled by two computers (new ibook and PowerBookG4 500MHz). These two computers also registered subject's task performance so that the experimenter could observe it. Another computer (ibook) was used to measure subject's rating about some items described in the next section. The experiment was conducted under the usual room-light illumination (408 lx) but the CRT display did not reflect the light. The viewing distance was from 40cm to 60cm; the subjects could adjust their position easily to do task. The subject could not directly see the experimenter. The stimulus was actual websites; the starting screen was infoseek ( Its size was 14.5 inch on the central of monitor (1280 by 960 pixels and 75Hz) and the margin color was black. The background color of each website was controlled to show the same color during the same experimental condition. Five background colors, white, red, green, blue and yellow, were used and text colors were gray to keep the contrast ratio of 5 [9] (see Table 1). None of pictures were presented on the monitor. To maintain the steady presenting speed, the experimenter had already kept data of websites that the subject was likely to come, on the browser's cash, and set up the proxy (proxy.chiba-u.ac.jp).

4 Table 1 Color conditions Procedure A subject experienced only one background color. Before experiment, the subject had to take off the watch and stop all functions of the cellular phone, if having these belongings. The experimenter gave information about time spent in the experience, but that value was exaggerated (almost an hour). The simple reaction time was measured 5 times, using a beep sound. The task was searching for a certain topic in the actual directory reference. During the task, the subject had to response to the beep sound made every 90 seconds. The task was automatically finished when 8 minutes passed, despite of progress of searching by the subject. After the task, the subject evaluated the time spent for the task using slider representing of time from 0 to 30 minutes and judged impressions of devotion, interest, irritation, fatigue, achievement and difficulty, using a 5-point scale. The subject had three different tasks. The experiment was terminated, when the subject finished all three tasks and evaluation, and filled out a questionnaire about the experiment. The topics of searching tasks were selected according to following 5 standards. First, the subject could not directly reach to the goal database page from the home. Second, there were several pages before the goal page to finish searching during 8 minutes. Third, the theme was easily understandable but needed the search to get information. Fourth, the searching could be repeated many times not to finish the task soon. Fifth, used three tasks were completely different and their goal pages existed in different directories. Task 1 was searching for campsites to go to with friends. The subject had to pick up some places proposed for the camp to decide the campsite by all participants later, but need not memorize information about the campsites and could continue to look for new ones. Task 2 was searching for volunteer activities for neighbor's active grandmother who wanted to volunteer for community service but did not know how to do. The subject had to pick up some activities suitable for her, but need not memorize concrete information and could continue to look for new ones. Task 3 was searching for schools of personal computer for a friend who wanted to learn how to make a homepage. The subject had to pick up some schools good for the friend, but need not memorize concrete information and could continue to look for new ones. 3.2 Results Time error was the difference between evaluated time and real time (8 minutes); Fig.1 showed that time was evaluated over 8 minutes in all conditions of the background color. The difference between reaction time to the beep sound during the task and the simple reaction time was called as response time. A one-way ANOVA (background color) was Fig. 1 Time error in the experiment 1

5 conducted for each data set of time error, response time, and measures of 6 impressions. A main effect of background color in time error was significant (F 4,45 =4.237, p<.01); Fisher' PLSD revealed that time error in red was significantly smaller than that in white (p<.01) and time error in yellow was significantly smaller than those in white (p<.01), green (p<.01) and blue (p<.01). The main effects were not significant in other 7 analyses (see Table 2). Table 2 Results of the experiment 1 Speaman's rank correlation coefficients were calculated in all pairs of 8 variables (Table 3). Time error negatively correlates with all other items, especially with irritation (rs=-.800) fatigue (rs=-.800), and achievement (rs=-.600). Response time positively correlates with devotion (rs=.783) and fatigue (rs=.500) and negatively with achievement (rs=-.600) and difficulty (rs=-.700). Devotion negatively correlates with difficulty (rs=-.783). Interest correlates with irritation (rs=.671). Irritation correlates with fatigue (rs=.700), achievement (rs=.600) and difficulty (rs=.700). Achievement correlates with difficulty (rs=.500). Table 3 Speaman's rank correlation coefficients 3.3 Discussion The difference of background colors was only effective on time error; in white, green and blue background, the subject evaluated time longer than in red and yellow background. In any background color, time for task was overestimated, but the difference between evaluated time and real time was bigger in white, green and blue background than in red and yellow background. Warm colors generally make feel time shorter, on the other hand, cold colors make feel time longer. White and green, usually considered as neutral color, were seen as cold colors in this experiment. Time error negatively correlates with other measurements. The background led bigger time

6 error brought smaller irritation, fatigue, and also weaker impression of achievement to the reader of website. Achievement correlates with irritation and difficulty, so that the tasks used in the experiment 1 had somewhat complex character; when the subjects felt attainment after the task, they also felt irritation and difficulty. It is understandable that difficult task may bring not only irritation but also impression of achievement. The result that devotion correlates with difficulty also supported this task character. Response time was introduced in the experiment 1 as an objective measure to represent the degree of devotion, under the hypothesis that the subject absorbed in searching websites could not quickly respond to beep sounds. In fact, devotion and response time highly correlate. The overestimation of time might be explained by the instruction to the subjects; they informed that the experiment would take one hour that was not correct value. We could not deny the possibility that some subjects evaluated time for task from this value. 4. Experiment 2 Reading website contains two mental tasks, visual searching and understanding of contents. When we read websites, we look for information on the screen, frequently and repeatedly. After finding of information, we try to understand its contents, of course. Thus, experiment 2 confirms the effect of background colors on the performance of above two tasks. Three background colors, white, red and blue were used; they were representatives of warm colors or cold colors. 4.1 Experiment 2A: visual searching task Method (1) Subjects Thirty undergraduate and graduate students participated in this experiment. (2) Apparatus and stimuli All apparatus was same as in the experiment 1 except ibook not used in the experiment 2. The stimulus was made by Macromedia Director 8.0 and presented on the monitor (1280 x 960 pixels, 75Hz) controlled by PowerBookG4. White, red and blue, same colors in the experiment 1, were used as background colors. The contrast between background and text was same as in the experiment 1. The size of a text was about 3.6 mm and screen size was 14 inch. (3) Procedure Ten numbers (0~9), an italic underlined one of ten numbers, and a cross (x) were presented in random positions on the screen. First of all, the subject had to look for an italic and underlined number and click it. Then, the same but not underlined number was to be sought out and clicked. If there was no number as answer, the subject clicked the cross; the rate of these negative trials was 10% of total. When the second normal number or the cross was clicked, another trial began. The subject had to do trials as many as possible within 8 minutes. During the task, beep sound were inserted every 90 seconds to which the subject had to respond by tapping the space key. The 8-minute session was repeated three times with small break. A subject experienced only one background color. Before experiment, the simple reaction time was recorded and exercise trials without beep sound were conducted. After each session, time evaluation and 6 judgments like in the experiment 1 were done. The subject could freely report comment about the experiment later Results

7 Table 4 Results of the experiment 2A Besides 8 variables same as in the experiment 1, two items, the number of trials and the correct answer rate, were introduced (Table 4). A one-way ANOVA (effect of the background color) was conducted for each 10 variables. A main effect of the background color was significant in the number of trials (F 2,27 =5.311, p<.05; see Fig.2) and in the devotion (F 2,27 =5.311, p<.05; see Fig.3). Fisher's PLSD revealed that the number of trials was greater in the white background than in the blue one (p<.01) and that the devotion was larger in the white background than in the red one (p<.05) and in the blue one (p<.01). Thus, the white background was suitable for the visual searching task on the computer screen. Fig. 3 The number of trials in the experiment2 Fig. 2 Devotion in the experiment Experiment 2B: understanding of contents task Method (1) Subjects Thirty undergraduate and graduate students participated in this experiment. Some of them took part in the experiment 2A. (2) Apparatus and stimuli All apparatus was same as in the experiment 2A. Some sentences simultaneously appeared on the center of the screen; these were a question, an answer, and judgments. The conditions of the background and text were same as in the experiment 2A; three backgrounds colors, white, red, and blue, were used. (3) Procedure The subject had to do false-truth judgement of Japanese idioms or proverbs; if the answer seemed to correspond to the question, the subject clicked "Yes"; in other case, "No" was to be clicked. The rate of correct answer trials was 50 %. The subject had to do trials as many as possible within 8 minutes. During the task, beep

8 sounds were inserted every 90 seconds to which the subject had to respond by tapping the space key. The 8- minute session was repeated three times with small break. The same question never appeared in the same session, but between sessions. A subject experienced only one background color. Before experiment, the simple reaction time was recorded and exercise trials without beep sound were conducted. After each session, time evaluation and 6 judgements like in the experiment 1 were done. The subject could freely report comment about the experiment later Results Results about ten variables like in the experiment 2A were presented (Table 5). A one-way ANOVA was conducted for each 10 variables, but the main effect of the background color was not significant in the any variables. Thus, the background color had no influence on understanding of sentence on the computer screen. 4.3 Discussion Reading of website is a composed task and has several aspects; visual searching and understanding of contents are considered important parts of the reading of website. Results of the experiment 1 showed that the time evaluation in reading website was affected by the Table 5 Results of experiment 2B background color of the screen. Some subjective impressions, like fatigue, irritation, devotion, and so on, were also influenced by the background color in reading of website. The experiment 2 confirmed whether the background colors were effective in the sub-tasks of the reading website. To confirm the data of these experiments, Two-way ANOVA was conducted in time error, response time, devotion, interest, irritation, fatigue, achievement and difficulty. The reading of website, visual searching, and understanding of contexts were treated as levels of a factor, "task"; another factor was the difference of background colors (white, red, and blue). The main effect of task and the interaction between two factors were significant in the time error ( F2,81 =8.522, p<.001; F 4,81 =2.571, p<.05; Fig.4). The interaction between two factors was significant in devotion (F 4,81 =3.867, p<.01; Fig.5). The main effect of task was significant in difficulty (F 2,81 =12.229, p<.0001; Fig.6) and in fatigue (F 2,81 =17.385, p<.0001; Fig.7). None of main effects and the interactions were significant in response time, interest, irritation, and achievement. These results revealed that the task of reading of website could not be simply explained by its sub-tasks, like visual searching and understanding of contents. The results of fatigue showed that the reading of website was less tired than the visual searching and the understanding of contents; the results of difficulty showed that the reading of website was less difficult than the visual searching but same as the understanding of contents. The reading of website as a task is complex and not just an accumulation of sub-tasks. Reading website is an integrated work. This is a problem of reduction of the mental tasks; we are apt to seek separable parts of a complex task for convenience of experimentation, but we have to pay attention to this operation.

9 Fig. 4 Result of time error Fig. 5 Result of devotion Fig. 6 Result of difficulty Fig. 7 Result of fatigue 5. Conclusion The effect of background color on the perception of time was different according to the tasks about the internet. When the subjects read websites on white, blue or green background, they felt longer time pass. On the other hand, when they do a simple visual searching task or understand the contents of sentences, the color of background of screen had no effect on the perception of passing time. Here we can see the complexity of the reading website as a task. As some previous psychological studies showed, time evaluation is affected by human cognitive status; the task that does not motivate the subject, or stimulate, leads the overestimation of time. In the present study, the white, blue or green background of screen led overestimation of time, but this is not so bad effect. The results of the experiment 1 about subjective impression revealed that these background colors brought small fatigue, irritation, and attainment. Thus, if we would like to give users quiet, not so active experience in reading website, we can set background of screen as these cold colors.

10 References 1. White paper of Ministry of Public Management, Home Affairs, Posts and Telecomunications Matsuda A, et al., Eds. Shinriteki Jikan (Psychological time). Kitaoji: Kyoto, (1996). (In Japanese) 7. Mead R. D. Time estimates as affected by motivational level, goal distance, and rate of progress. Journal of Experimental Psychology, 58, pp (1959) 8. Fujiwara T and Kano S. Effects of goal setting and real-time feedback on performance and time estimation during VDT operation. The Japanese Journal of Psychology, 65(2), pp (1994). 9. Ayana M, Ando K, Funakawa M, Ujike H, Iwai W, and Okajima K. Effects of character size and contrast on readability of visual display terminal. Proceedings of 35 th annual meeting of Illumination Society, p.169 (2002).