Rita Kosztyánné Mátrai THE ROLE OF OBJECTS PROPERTIES AND LAYOUT IN USER INTERFACE DESIGN. PhD Thesis. Supervisor: Cecília Sik-Lányi

Transcription

1 Rita Kosztyánné Mátrai THE ROLE OF OBJECTS PROPERTIES AND LAYOUT IN USER INTERFACE DESIGN PhD Thesis Supervisor: Cecília Sik-Lányi University of Pannonia Information Science and Technology PhD School Veszprém 2010.

2 Introduction Many factors influence the transparency of a web page or software interface: the amounts of information on the screen, organizing information, font size, background etc. All of these parameters provide the overall picture which the user sees on the screen. The user interface of a web page or software is excellent if users find easily the information what they need. How can we characterize the perspicuity of user interfaces? One of the most frequent task of a user is information seeking. Therefore it seems to be logical to give search tasks to the users and characterize perspicuous of a user interface on the basis of search time and navigation structure. Efficiency of search is influenced by several factors which impacts are hard to measure. In case of information seeking task on the interface of software or home page, the effect of a several factors appear and affect click time. Numerous researches are dealing with the effect of each factor separately and altogether. In the international literature it seems when compiling experiments the effect of each factor or two or three factors joint effects are examined through deliberately simplified tasks and as a result conclusions are drawn on design user interfaces. Therefore I also followed this approach. The aim of my research was to characterize the efficiency of user interfaces where, users had to solve search tasks in which more objects had to be found and the targets had to be clicked as well. More than 100 average users and 45 users with mild intellectual disabilities 1 were involved in these experiments. To characterize navigation strategies of the users a method was developed. With this method users within-page navigation can be characterized on multimedia programs and home pages. I examined how properties of objects (eg. form, size, position; in case of texts: font type, font size, word length) influence solving time and navigation structure. Introducing new metrics was also necessary with which clicking sequences of users can be compared to each other within different user groups. [6, 16] I worked out exact statistical and graph-theoretical methods to draw a map of navigation routes. With the help of my method I can construct a so-called navigation map which contains 1 They belong to category of "SNI A", thus, pupils with special education needs with organic damaged background. According to WHO definition, their IQ values are between 30 and 50. The expertise is given with the sign BNO 71 by the Experts Committee for Testing Learning Abilities. 1

3 the sequence of the selected objects and shows the routes of clickings. I determined these navigation structures/navigation maps according to the different target groups. On the base of the navigation maps the most probable navigation routes could be determined. I compared to the general and intellectual disabled groups navigation routes and examined to what extent routes are characterized and significant in the target groups. I also applied and developed statistical indexes, with which one can not only analyse whether characteristic navigation route exists in each target groups or not, but also denote with figures how different or how similar the experimental people s navigation routes are. I compared the results of the target groups, drew conclusions and elaborated guidelines. I also improved another method with which it can predicted if one knows the attributes (position, size, colour, background colour, etc.) of an object, then how many tries one need to find the object. I compared the reliability of these considering the navigation routes of each target groups. Assumptions for research models In order to analyse users navigation structure, such search tasks were needed in which not only one but also more objects had to be discovered on home pages or on the interface of softwares. During the search tasks mostly objects with same properties (eg. size, form, colour, etc.) had to be discovered to allow users to concentrate on objects with the same properties while searching. In two further tasks all occurrences of three different objects had to be discovered where the disturbing effect of more objects with different properties were investigated. How each factor affects search time, and to what extent these parameters promote or hinder users to find information? Can these helping/disturbing effect of the parameter be made numeric? In my experiments first I placed geometric forms and figures on the screen because in this case one did not have to interpret text. After that I continued my experiments with tasks where one had to search in text appeared on the screen, therefore more cognitive function took place during the navigation. Assumptions given below were used for creating research models, in my research I endeavoured to make calculations for these parameters. Assumptions for navigation in multimedia programs: [1, 5, 6, 16, 19] 2

4 i. I assumed that placement, size and form of objects influence search time and navigation. ii. I assumed that properties of objects (size, form, rotation) affect search time and searching route in different way by average users and users with mild intellectual disabilities. iii. I assumed that tasks in 3D space (which was made on the analogy of the 2D tasks) reaction time becomes greater in the same task, and visual properties of objects affect reaction time and searching route in different way. iv. I assumed that navigation tasks which engage short term memory in greater extent can be solved more difficult by users with mild intellectual disabilities. Assumptions for searching and navigation on textual pages: [5, 15] v. I assumed that meaningless context requires longer solving time, because it makes the recognition of non-target words more difficult, therefore the eye does not slide across so fast through the non-targets. If non-targets are also meaningful words, then users can recognize them in shorter time (because their mental dictionary contains that word), therefore they can scan the screen faster. vi. I assumed that the longer the words are the longer time is needed to solve the task, because longer words need more fixations to read them. vii. I assumed that the darker the background is the longer the solving time will become, because for effective search sharp-sightedness is also needed which can be promoted by increasing luminance (to a certain extent). viii. I assumed that the smaller area of the screen is scanned the shorter the solving time will be, because in this case the route of eyes movements becomes shorter. In my experiments I endeavoured making calculations for the effect of these parameters on information seeking. Thesis First, I developed methods for analysing navigation tasks with which the most probable clicking sequences of a navigation task can be determined and the so-called navigation graphs can be drawned. By analyzing clicking sequences, navigation orders and clicking scale preferences can also be determined. 3

5 T1. With the similarity and identity coefficients two clicking sequences can be compared, with the similarity and identity indexes the concentration of clicking sequences can be determined. These formulas can be used to determine how similar the users navigation routes to any kind of searching strategy. [15, 19] The suggested (similarity, identity) coefficients and indexes can be used for characterizing clicking orders widely like the rank correlation coefficients in case of comparing clicking orders. The method takes into consideration both the clicking orders and the occurrence of element sequences. T2. With the suggested clicking scale preference map it can be examined which targets were found sooner and which targets were preferred during clickings. [15, 19] With my method, not only clicking sequences but also going directions can be determined and characterized. I used these methods for all tasks and compare average users navigation structures to users with mild intellectual disabilities. T3. Navigation graphs, navigation structures, navigation and preference maps can be determined if we know clicking orders and on the basis of these users navigation strategy can be characterized. [15, 19] If the number of targets increases, then the most probable searching strategy becomes from global to local first and after that from local to ad-hoc. In case of users with mild intellectual disabilities local and ad-hoc strategies can occur in case of fewer numbers of targets. If tasks are made more difficult by changing more parameters of targets, than the change of searching strategies from global to local and to ad-hoc can be observed rapidly. This establishment is more valid in the case of users with mild intellectual disabilities. T4. In case of average users and those with mild intellectual disabilities if the number of targets increases then searching strategies will be as follows: global, if the number of targets is not greater than 5, local in case of 6-9 targets, ad-hoc in case of 10 or more targets. a. Local and ad-hoc strategy can occur in case of fewer targets if: i. not only position but also size and direction of rotation of target changes, 4

6 ii. users have to search 3D-objects. b. In case of users with mild intellectual disabilities, if, except for the position, more target properties change (eg. size, direction of rotation, form), searching strategy became ad-hoc sooner in function of the number of targets than by average users. [14, 15, 16, 19] Choosing logical layout and background promote users with mild intellectual disabilities to find targets easier. T5. Reaction times are linear functions of the number of the targets if the number of target is between 7 and 10 in case of average users and between 4 and 5 in case of users with mild intellectual disabilities. a. If the background conceptually relates to the targets then reaction times of users with mild intellectual disabilities can be approached by linear trend in case of 7-8 targets, thus, not only their navigation can be improved but also their reaction times can be decreased. b. If targets deviate with more parameters from each other expect for their location (eg. size, direction of rotation, form), then in case of fewer number of targets (5-7) reaction times can be approached by nonlinear trend as well. i. The reaction times of users with mild intellectual disabilities are more sensitive to the changes of target parameters, thus, reaction times determined in function of number of targets can be approached with nonlinear trend in case of fewer number (3-4) of targets as well. c. In case of textual search tasks more column layout promotes users navigation. In this case reaction times can be approached by linear trend if the number of the targets is not greater than 9. [15, 20] Major publications Hungarian conferences 1. Mátrai Rita, Kosztyán Zsolt Tibor, Sikné dr. Lányi Cecília: Speciális szükségletű felhasználók navigációjának vizsgálata különböző multimédiás alkalmazásokban. 5

7 (Analysing navigation of users with special needs in case of different kind of multimedia applications.) Lux et Color Vespremiensis, Veszprém, október Mátrai Rita, Sikné Lányi Cecília, Kosztyán Zsolt Tibor, Schanda János: Színek és kontúrok szerepe a navigációban. (The role of colours and contours in navigation.) XXX. Jubileumi Kolorisztikai Szimpózium, Eger, május 30. június Mátrai Rita, Molnár Gábor, Sikné Lányi Cecília: Weblaptervezési kérdések vizsgálata gyengénlátó felhasználók számára. (Investigating design problems of web page design for partially sighted users.) Lux et Color Vespremiensis, Veszprém, október Mátrai Rita: Valóban azt látjuk, ami a retinára vetül? (Do we really see what is projected on the retina?) Lux et Color Vespremiensis, Veszprém, november 8. (A kiadvány CD-n jelent meg.) 5. Mátrai Rita: A vizuális figyelem vizsgálata multimédia programokban és weboldalakon. (Examination of visual attention in multimedia programs and home pages.) XXXII. Kolorisztikai Szimpózium, Eger, május Lukács Gyula Emlékverseny I. Díj. International conferences 6. Sik Lányi C, Bacsa E, Mátrai R, Kosztyán Zs, Pataky I: The Design Question of Development of Multimedia Educational Software for Aphasia Patients, Lecture Notes in Computer Science, LNCS 3118, ICCHP 2004, Springer Verlag Berlin- Heidelberg, pp: ISSN (impact factor: 0.513) 7. Rita Mátrai, Zsolt Kosztyán, Cecília Sik-Lányi: Design of the User Interface of a Multimedia Skill-improving Programs Developed for Children Suffering from Dyslexia, CEIMVRC (First Central European Multimedia and Virtual Reality Conference) 2004, Veszprém, Hungary, May. 6-8., pp Cecília Sik-Lányi, Ferenc Fapál, Rita Mátrai: Folk-Tales for Everybody WEB Page. CEMVRC (Central European Multimedia and Virtual Reality Conference) 2005, 8-10 June 2005, Prague, Czech Republic, pp

8 9. Rita Mátrai, Cecília Sik-Lányi, Zsolt Tibor Kosztyán: Games Test to Study the Navigation of Handicapped Children. CEMVRC (Central European Multimedia and Virtual Reality Conference) 2005, 8-10 June 2005, Prague, Czech Republic, pp Gábor Molnár, Cecília Sik-Lányi, Rita Mátrai: Homepage design for e-learning considering Web Content Accessibility Guidelines (WCAG) for low vision users. 8th European Conference for the Advancement of Assistive Technology (AAATE 2005), 6-9 Sept. 2005, Lille, France, pp Rita Mátrai, Cecília Sik-Lányi, Zsolt-Tibor Kosztyán, János Schanda: The importance of colours and contours in navigation. Lux Junior 2005, Sept. 2005, Dörnfeld, Deutschland, p Rita Mátrai, Bálint Persics, Cecília Sik-Lányi: The effect of colours and sizes in visual search. Usability Day IV., 9. Juni 2006, Fachhochschule Vorarlberg in Dornbirn, Österreich, pp Rita Mátrai: Analysing the navigation and information retrieval of mentally impaired children. Central European Multimedia and Virtual Reality Conference 6-8 November 2006, pp ISBN: Rita Mátrai, Cecília Sik-Lányi: Investigation of navigation routes of normal children and those with mild intellectual disabilities. 9th European Conference for the Advancement of Assistive Technology (AAATE 2007), 3-5 October, San Sebastian, Spain. 15. Rita Mátrai, Zsolt T. Kosztyán, Cecília Sik-Lányi: Analysing the 2D, 3D and Web User Interface Navigation Structures of Normal Users and Users with Mild Intellectual Disabilities. Lecture Notes in Computer Science, LNCS 5105, 2008, Springer Verlag Berlin-Heidelberg, pp International articles 16. Cecília Sik-Lányi, Rita Mátrai, Gábor Molnár, Zsuzsanna Lányi: User interface design for visually impaired children. Elektrotechnik und Informationstechnik, Heft 12, 2005, Springer, Wien, New York, pp , ISSN X 7

9 17. Sik Lányi C, Bacsa E, Mátrai R, Kosztyán Zs: Developing interactive multimedia rehabilitation software for treating patients with aphasia, International Journal on Disability and Human Development, Special issue on disability, virtual reality and associated technologies, (3) pp ISSN X 18. Cecília Sik-Lányi, Rita Mátrai, István Tarjányi: Analyzing navigation of mentally impaired children in virtual environments. International Journal on Disability and Human Development, Vol. 5, No. 3, 2006, pp Rita Mátrai, Zsolt Tibor Kosztyán, Cecília Sik-Lányi: Navigation method of special needs users in multimedia systems. Computers in Human Behavior, Volume 24, Issue 4, Special Issue: Integration of Human Factors in Networked Computing, 2008, pp (impact factor: 1.767) Book chapter 20. Rita Mátrai, Zsolt Tibor Kosztyán: Navigation strategies in case of different kind of user interfaces. User Interfaces. In-Tech Publishing, ISBN (in press) 8