User-Experience of Human Computer Interaction (HCI) in Mobile Phones Dr

108 Int'l Conf. Internet Computing and Internet of Things | ICOMP'16 |

User-Experience of Human Computer Interaction (HCI) in Mobile Phones Dr. Minerva M. Bunagan1, and Prof. Nabil El Kadhi2 1Asst. Professor, College of Business, UoB, Buraimi, Oman 2Deputy Vice Chancellor for Academic Affairs, UoB, Buraimi, Oman

help in dealing with daily activities that require easy and Abstract – Users consider some characteristics in selecting a reliable information [5]. mobile device. These characteristics include interface design, efficiency, reliability, presence of utilities, responsiveness, The presence of various types and brands of mobile portability, performance and advanced features. On the other phones in the market provides sufficient options to the users. hand, mobile developers apply HCI principles in designing The features available in each mobile phone depend on the mobile devices and consider the user-experience as well. operating system, from which it is based. There are mobile Mobile users reflected their experience of the 7 HCI devices that are based on IOS, Android, Windows, Blackberry principles in their commentaries and it appeared that the most and Symbian, which is now gradually disappearing under the relevant principles are consistency, synthesizability and ownership of Microsoft [6]. substitutivity. To specifically determine the effect of a specific Most users however choose mobile phones in design principle on a certain product, the study recommends consideration of the camera, memory capacity, music, video, exploring the prioritization of the HCI principles as gaming, downloading, and surfing capabilities. Moreover, implemented by the mobile phone developers. This will pave they take into account the size, weight, functionality, and ease way for the differentiation of design principles applicable to of use. All of these speak of the experience of the user along hardware or software. mobile interaction. Keywords: Mobile Computing, Mobile Characteristics, Mobile interaction is an aspect of Human Computer Mobile Interaction, Human Computer Interaction, Design Interaction (HCI), which deals with the manner to which Principles, User-Experience, mobile users interface with computers. It focuses on the 1. Introduction understanding of mobile users’ requirements and needs [7]. Statistics shows that mobile subscribers are widespread As HCI involves the study on how the users/ human and all over the world. The International Telecommunication the computer/ machine interface with each other, it takes into Union estimated that there are 6 billion mobile subscriptions, account the relevant aspects of the two (2) elements. For which make up 87% of the world population [1]. The increase instance, it looks into the techniques in computer graphics, the on mobile subscriptions from 2010 to 2011 is 0.6 billion and operating system, the programming language and the from 2009 to 2010 is 0.7 billion. It was also estimated that by development environment of the machine; and the graphic the end of 2012, there will be 6.5 billion mobile subscribers design and industrial design principles, human factor such as and 6.9 billion by the end of 2013 [2]. Moreover, in the early user satisfaction and communication theory, among others of 2014 report on mobile users, it was expected that mobile users the user [8]. in 2014 will grow to 4.55 billion worldwide and by the end of The application and involvement of HCI in the design of 2015 there will be 8 billion mobile subscribers [3]. In mobile devices should not be ignored to ensure that mobile addition, it is estimated that the total number of mobile devices are appropriately designed. It should also be noted broadband connections will include for almost 70% of the that HCI provides relevant findings along user experience, global base by 2020, as compared to 2014, which is around which help a lot in for the improvement of systems and 40% [4]. These data indicate that there is much growth in the devices [9]. use of mobile phones all over the world. This could be attributed to the fact that individuals depend so much on 2. Research Problem mobile phones today and mobile phones have already become Studies reveal that HCI is a discipline without a fusing a necessity in the daily lives of the individuals as well. design interface, and there is no coherence and consistency in In the early stage of mobile technology, mobile phones measuring HCI interface performance. However, a study on were just used for calls and messages. Today, the HCI Principles was conducted to standardize the variety of advancement in mobile technology is hard to cope with. principles which have been proposed by several authors. The Mobile phones have a lot of features now, which include text result of the study showed the eight (8) HCI Principles [10], and image messaging, simple calls and video calls, Internet namely: 1) recoverability; 2) familiarity; 3) consistency; access, GPS-based navigations, music, gaming, social 4) substitutivity; 5) task migratability; 6) synthesisability; networking and various applications which provide users great 7) predictability; and 8) perceptual ergonomics. These

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principles can be applied to the design of interfaces in mobile 4. Discussion devices. 4.1 Challenges in Mobile Design Mobile devices of different kinds and with varied features and interfaces are widely used everywhere. Researches show The HCI challenge in the mobile device design lies that there are many challenges faced by those involved in on its hardware and software design [11]. The limited input designing mobile devices, which include limited input and and output facilities, and designing for mobility are the output facilities, designing for mobility, hierarchical menus, hardware challenge, and the hierarchical menus, navigating navigating and browsing, and images and icons [11]. and browsing, and images and icons are the software challenge. Since mobile devices are used in various disciplines, such as education, medicine and sociology, major emphasis should The three input facilities for mobile devices are be placed on how the user interacts with the device. This keyboard, stylus and the scroll wheel. Among these facilities, would only be possible if there is a set of appropriate design the challenge is on the design of the keyboard as the space for principles that can be applied in mobile devices. it is limited [11]. However, the keyboard allows the user to have more accurate entry than the stylus [12, 13]. An Moreover, Mobile phone developers come out with new experiment was performed to compare text-based entry using product releases in response to the growing need of the users mini-qwerty, hand-writing recognition, quick writing, and a along functionality, usability, ease of use, among others. chorded keyboard; and it was found out that the mini-qwerty These user requirements are based on the user’s experience. is the fastest way in entering text and the two-chorded Users seek for better ways to improve mobile performance keyboard is the best of the methods in terms of accuracy [12]. based on their need and personal interaction with the device. Though user experience design is considered in the design of With the problem on the space taken by the keyboard, mobile phones, HCI principles should not be taken aside. due to the small size of the mobile device, new designs of mobile devices have been out in the market, where the touch As there is no standard set of HCI principles for mobile screen keyboard replaced the physical keyboard. A very good device design, there is a need to come out with specific design example for this is the iPhone and the Android Phones. An principles or criteria that would be able to meet what the experiment on the comparison of a physical keyboard and a mobile device is intended for. This study explored how HCI touch screen keyboard was conducted, where the Palm Treo principles can be applied to mobile devices by looking into was used for the physical keyboard and the Samsung i718 was the characteristics users preferred to have from mobile devices used for the touch screen keyboard. It was found out in the and mapping these against the HCI design principles. It also study that the use of physical keyboards proved to be faster rests on the concept that the design of mobile phones is and more accurate in entering text as compared to the touch influenced by the 2 factors – user experience design and HCI screen keyboard. However, the addition of tactile feedback in Principles. the touch screen keyboard gave a comparable result with the 3. Methodology physical keyboard. The authors then recommended that tactile feedback be added as feature of the mobile device [13]. The study employed the descriptive research design, A study on tactile feedback was also conducted and it was where data were gathered in 2 ways - meta-analysis and reinforced that tactile feedback helps a lot in improving the surveys. The meta-analysis was conducted to review user performance with the mobile. In the study, the users were systematically various findings on HCI principles and come able to find greater satisfaction in interacting with the touch out with the concrete principles in HCI. As there were screen [14]. conflicting issues on HCI principles, it is appropriate to extract the conflicting views of various authors and be able to Various studies have shown that users still prefer to use deduce specific principles that serve as basis to continue with keyboards for entering text, as it proved to be accurate and the study. Findings were grouped according to the general faster [11, 13]. The challenge then on the limited space for the principles of HCI, which include: recoverability; familiarity; keyboard led to the design of touch screen keyboard and the consistency; substitutivity; task migratability; synthesisability; said type of keyboard is almost the same as the physical predictability; and perceptual ergonomics. The findings keyboard with the presence of the tactile feedback, and like collected along these principles served as basis for the physical keyboard, it brought user performance, accurate comprehensive analysis of the specific descriptions and and faster text entry. considerations for each principle. The survey method included Moreover, two output facilities which are considered on-line literature reviews or feedback on mobile devices from limited are screen and audio [10]. The challenge as regards 297 mobile users. They were categorized based on the general limited output facilities lies on the size of the screen. A study characteristics of mobile devices preferred by the users. After on the mobile device design in response to the difficulty of taking into consideration the on-line reviews, they were viewing huge information from many applications was mapped against the HCI principles. An analysis was made as conducted and it was found out that the combination of fish- to which HCI principles are applied in the design of the eye and semantic zooming techniques would greatly help the mobile devices. user visualize the amount of information, even with a small

ISBN: 1-60132-439-1, CSREA Press © 110 Int'l Conf. Internet Computing and Internet of Things | ICOMP'16 |

screen [15]. There is also a challenge in viewing maps, migratability; synthesisability; predictability; and perceptual photographs and other huge amount of information, and this is ergonomics [10]. the difficulty in doing spatial activities. Although users can Recoverability principle involves ways by which the user utilize the panning and the zooming techniques for viewing is able to recover from an error he usually makes. There are such huge information, these activities are considered tedious two types of error recovery -- forward and backward. In in working with spatial tasks. The three techniques for spatial forward recovery, the user is able to prevent making the error; activities – Halo, Arrows and Citylights were compared and it and in backward recovery, the user is able to reverse the error was found out that Halo and Arrow-based visualizations do made. not vary differently in working on simple spatial activities [16]. The familiarity principle focuses on the experience and understanding of the user in interfacing with the system. It On mobility, since a mobile device is carried by the user tries to determine how much the user knows about the system anywhere and anytime, portability and the power facility and compares to the appropriate or prescribed way of using should be primarily considered. There are varied instances by the system. which the power is consumed and the consumption is based on the desired applications or performance level of the user Consistency involves how the user uniformly behaves or [11]. performs tasks in similar scenarios. It considers the actions of the user in interfacing with the input and output facilities of Due to the challenge brought about by the power facility the system, among others. of mobile devices, the challenges of the power and thermal architecture were reviewed, and at the same time design Substituvity is providing the user with an option or considerations for mobile hardware and software to ensure alternative to execute a task. By choosing either of the performance and maximize the power were proposed [17]. options, the user is able to achieve the same thing. An example of this is using a certain icon or a hierarchical menu Hierarchical Menus are list of options in several levels, to open an inbox. available for the user to perform certain tasks. These are typically selected by clicking or tapping the menu, in the case Task migratability pertains to the state of allowing the of touch screens [18]. The challenge on hierarchical menus system to do the task that can be done by the user. The user has something to do with its structure. It was mentioned that transfers some responsibilities to the system. A good example researches have been conducted regarding the number menus of this is allowing the system to check the grammar of the and the submenus in the mobile phones; however, there are document, which could also bring some drawbacks as there conflicting ideas as to which structure provides more efficient are instances when the system is not able to understand or interaction [11]. convey what is exactly meant by the user. Barell Menu as an alternative to hierarchical menu was Synthesisability provides the user the ability to simulate proposed. Its prototype was designed and its usability was what happens in interfacing with the system. The user is able compared with devices having hierarchical menu. It was to check or trace what happens after asking the system to do revealed that it takes fewer steps to navigate through the some tasks. An example of this is when the user performs menus using their prototype. Though the Barrell Menu proved transferring of the files, the user is able to know whether the to be efficient more than the hierarchical menu, the users still file is transferred when the file is already in the desired prefer the hierarchical menu as they are used to it already location. [18]. Predictability enables the user to determine what happens The challenge on navigating and browsing is related to whenever the user executes a task. The user is able to perceive the limited output facility as there is a difficulty along these the result after selecting a menu or pressing a key. due to the size of the screen [11]. There are problems in mobile browsing, particularly on viewing information as Perceptual ergonomics allows the system to detect human perceptions. The interface should have the facility of compared to the desktop. Designs should be taken into monitoring how the user recognizes things. account by mobile website designers to improve readability [19]. 4.3 Characteristics of Mobile Phones Required by the Images and icons as well pose a challenge in the mobile User design as downsizing them from desktop to fit mobile devices Mobile phone characteristics required by the user can be should not be ignored. Various studies, which gave categorized into nine (9): interface design, efficiency, considerations in designing images and icons for mobile reliability, presence of utilities, responsiveness, portability, devices were conducted though [11]. performance, functionality and advanced features. 4.2 HCI Design Principles Interface refers to the over-all look and feel of the users A review and analysis of HCI design principles was done on the device. It includes the ability to easily use, learn and and 8 design principles were identified. These are recognize the appropriateness of the device. [20] The mobile phone users look for simplicity, ease of use, access and recoverability; familiarity; consistency; substitutivity; task operation. They appreciate mobile phones which allow them

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to easily learn and navigate around the phone. They like Responsiveness in this context refers to the ability of the mobile phones which are easy to operate, control and conform device to work or perform quickly or consistently in the to their expectations. They attribute this to the type of the presence of external conditions such as speed and load. Operating System in the mobile and the design of the mobile Mobile phone users appreciate that their mobile phone is fast interface itself. The mobile users specifically mentioned in to do tasks and responds quickly. their testimonies that they stick to a specific mobile device Portability pertains to the manner by which the user is due to their familiarity on the device. Some users also able to smoothly perform the same tasks from one device to mentioned that the kind of interface relies primarily on the another efficiently and effectively. [20] Mobile phone users Operating System itself. In addition, mobile phone users focus expressed their satisfaction of their phones which allow them on the interface aesthetics, where they can find pleasure or to continue to perform same tasks on similar devices; hence satisfaction on the way they interact with the device. they are able to do integration with other devices. They Efficiency includes the ability of the device to accurately appreciate that the mobile phones have the ability to and completely allow the users to achieve their goals with the automatically synchronize tasks and data, such as contacts and given resources. This can be influenced by 3 factors – applications. performance efficiency, time behavior and capacity. The Performance refers to the responsiveness of the device to performance efficiency pertains to how the device performs execute the tasks required and needed within an expected under the given conditions. Time behavior refers to the time. [21] Mobile phone users require that they can have a amount of time the device is able to respond or process in smooth shifting of task from one option to another. They achieving the goal. Capacity refers to the maximum limit of mentioned that their mobile phones really do what they ought the devise in meeting the requirements. [20] This to do, run smoothly, have fluidity in response and their characteristic allows the user to be able to achieve the tasks he responses are reliable. They also appreciate that there are expects from the phone with minimum effort, time and available icons to access and that the phones do what they are resources. This includes the ability of the mobile phone to expected to do. They emphasized that their phones handle check and edit mails and messages at a certain period, to use multi-task and do not disrupt their user experience. They also the camera as it is expected to function, to have a battery highlighted that the response is not affected even when which does not run out of charge for a very short of time, to charging the phone. They particularly cited the use of maps as make and receive calls properly. Mobile users choose phones being able to give them accurate data. which can provide them the satisfaction to perform all the tasks they expect from the phone without any hassle or Functionality includes the properties that show how tasks problem. They complain about phones whose battery drains so perform the stated or implied needs. [22] Mobile phone users fast. They appreciate their phones for being able to do the mentioned that the performance of their mobile phones is expected tasks at minimal effort and time. predicted, easy to figure out, can back-up all information that they have in their phones and have smooth performance. For Reliability refers to the degree to which the device is able instance in some mobile phones, users are able to know what to perform specified functions or tasks for a certain period of happens when they pinch or slide on the interface. They also time. This includes the ability of the device to perform as said that their phones are stable and have no problem in intended in spite of problems on hardware or software. [20] connecting with others and other devices. Mobile phone users appreciate phones which have provision for extending battery and memory to allow them to be able to Advanced features include all other functions that mobile perform various functions with the phone without users require from the mobile phones. These include auto- interruption. Some users also appreciate the unique feature of detection of movements, auto-adjustment in brightness, and a removable battery which they can keep charging for times the use of hand gestures for phone functions. when they do not have access to charger or outlet. 4.4 HCI Design Principles Applicable to Mobile Phones Presence of utilities includes the availability of options or alternative tasks which the user can use as needed. Mobile Mobile Phone Characteristics–HCI Design Principles Map users require buttons or options for some tasks, such as In the section above, characteristics of mobile phones playback and ring back. They mentioned that it is easier for preferred by the users were explained. These characteristics them to have options to remove unwanted applications, and served as the basis in identifying the HCI design principles design. They also want a provision for other browsers in the applicable in mobile devices as experienced by the users. same phone. Although there are also mobile phones which are Table 1 shows the mapping of these mobile phone redundant in menus and icons, they still would prefer other characteristics to the HCI Principles. These mobile alternatives to do tasks. For instance, in entering a password characteristics surfaced in the commentaries of the mobile for the device, they can use either codes or by the finger users extracted from on-line mobile surveys covering 2014, prints. Moreover, the presence of options for battery saving, 2015 and early part of 2016. for input of data, and for notification drop down is among the most visible provision of alternatives for the mobile phones. Considering the given definitions and significance of both the HCI principles as well as the mobile phone characteristics, Table 1 showing the mapping is derived.

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In order to evaluate the importance and prioritization of The characteristic – functionality is mapped with the HCI the HCI principles based on user experiences, and as a first principle – predictability. This principle states that the user is step, a one-to-one mapping, where each HCI principle is able to determine what happens when a task is executed; mapped to the most relevant mobile characteristic is hence all user responses and commentaries expressing the considered. Table 2 presents the considered mapping which user’s requirements, needs or observations on how the mobile was used in the statistical analysis. devices are able to operate based on some specific criteria were included here. Table 1 – Mapping of Mobile Phone Characteristics to the HCI Principles The characteristic – advanced features is mapped with the HCI principle - perceptual ergonomics since all those Mobile Phone HCI Principles responses and commentaries mentioned have something to do Characteristics FM CN SB TM SN PR PE with detecting human perception and sensory. 1. Interface 33 Design There is no mobile characteristic required by the user that 2. Efficiency 3 3 can be mapped to the principle – recoverability. However, this 3. Reliability 3 does not mean that the principle recoverability is no longer 4. Presence of applied in mobile devices. It should be noted that the mobile 33 utilities phone developers in their Design Guidelines reflect this 5. Responsiveness 3 principle by giving the user chance to reverse the actions. This 6. Portability 3 may be true for the applications, but not in the mobile phone 7. Performance 3 3 3 itself as the users are not able to retrieve or recover loss of data as soon as a mistake has been made. [23] An instance of 8. Functionality 3 this is the presence of the icloud storage in some mobile 9. Advanced 33devices, where data, applications, phone settings, homescreen Features * FM – Familiarity CN – Consistency SB – Substitutivity and many more can be recovered [24]. TM – Task Migratability SN – Synthesizability Table 2 – Mapping of Mobile Phone Characteristics to the PR – Predictability PE – Perceptual Ergonomics HCI Principles As shown in Table 2, the characteristic Interface is Mobile Phone mapped to HCI Principle – Familiarity, since familiarity HCI Principles pertains to the understanding of the interface. All responses Characteristics and commentaries reflecting various instances and 1. Interface Design Familiarity experiences dealing with ease of access and in dealing with 2. Efficiency Consistency interfaces were included under this mapping. 3. Reliability Consistency The characteristics – efficiency and reliability are mapped 4. Presence of utilities Substitutivity to the HCI Principle – Consistency. As this principle speaks 5. Responsiveness Task Migratability about how a user can uniformly behave and perform tasks in similar scenarios, all responses and commentaries dealing 6. Portability Task Migratability with how the mobile phones respond consistently with the 7. Performance Synthesizability tasks given by the users, from simple mails and messages to 8. Functionality Predictability making calls were included. 9. Advanced Features Perceptual ergonomics The characteristic – presence of utilities was mapped to the HCI Principle – Substitutivity as the principle speaks Applicability of HCI Design Principles in Mobile Devices about availability of options to execute a task. All user As presented in the discussion above, there are 7 HCI responses and commentaries that mentioned about provision design principles that were mapped to the mobile of alternative options, such as buttons and short-cuts to characteristics preferred by the user. These principles though perform some commands were included in this mapping. do not have the same level of importance or priority when it The characteristics – responsiveness and portability are comes to its applicability in mobile devices. Considering the mapped with the HCI Principle – Task Migratability. Since commentaries of 297 mobile users, which were tallied against this principle covers aspects that allow the system to do what the HCI Design Principles, their perception of the HCI design the user requires, all responses and commentaries on how the principles applied in mobile devices, was determined. As mobile device functions the tasks the user expects it to do shown in figure 1, the 7 HCI design principles have varying were included here. values, and the principle having the most value is consistency (254/297) and the least is perceptual ergonomics (43/297). The characteristic – performance is mapped with the HCI The data indicate that users rank consistency as the HCI Principle – Synthesizability. Since the principle tackles what design principle that should be applied first in mobile devices. happens in interfacing with the system, all user responses and This is followed by Synthesizability (207/297), Substitutivity commentaries regarding the ways by which their mobile (188/297) and Familiarity (149/297). phones respond to whatever tasks given were mapped here.

The HCI Design Principle – Consistency being the principle which is evidently applied in mobile devices as Figure 2: User Perception on the perceived by the respondents can be attributed to the fact that Applicability of HCI Design Principles mobile developers see to it that there is consistency in the design of their products. They ensure that in any interface, the Consistency mobile phone user does not have to learn new technique for 4.31 6.02 Synthesizability every application or interface or neither has to be confused in 9.63 25.48 using many icons for the same purpose. [23] Substitutivity 14.94 Figure 1: Applicability of HCI Design Familiarity Principles in Mobile Devices 20.76 18.86 Task Migratability

300 Predictability 250 Perceptual 200 Ergonomics 150 254 100 207 188 149 50 96 Moreover, the principle HCI – predictability can be 60 43 0 manifested on how the user manipulates the device. Mobile phone developers identify actions on the device by explicit Frequency of User-Experience Frequency and implicit, where they consider the result of the action to an object (explicit) and the result of the action through images or visuals as signs or indicators (implied). For instance, dragging and dropping a set of objects can result to many different HCI Design Principles things, however nothing is explicitly stated; and with this users rely on the graphical prompts or clues such as change on how the pointer appears to be able to determine the result of A better analysis can be made by showing how one (1) the action. principle relate to the other six (6) principles., and this can be shown in Figure 2. The figure shows that there is 25.48% The HCI principle – Recoverability is manifested in user-experience on the principle – consistency, 20.76% on the situations where the user is able to reverse the action. Mobile principle – Synthesizability and 18.86% on the principle developers provide ways to let the users feel that they can try Substitutivity. This implies that of the seven (7) principles, to do things or explore on the device without a losing their users seek for the presence of the principles – consistency, data. Some options that mobile developers include in the synthesizability and substituvity in mobile devices. These design is the availability of prompts to cancel or undo a principles are more evident in mobile devices as they make up certain task executed. For instance, in editing an image in a to 65% of the total user-experience. certain phone, the user can modify the image as much as he wants without changing the image file until such time that he 4.5 View of Mobile Phone Developers on HCI Principles finalizes or saves the modification. He can leave the changes to the image by the option cancel. Mobile phone developers have their own set of design principles applying the principles for human-computer It is also worthy to note that mobile phone developers use interaction in coming up with a product that is elegant, the user-focused approached in designing their product. They efficient, intuitive, and delightful. The HCI principles applied consider their target audience and use a specific technique to by the mobile developers can be evidenced in the styles of the ensure that they deliver a product that meets user products themselves. For instance, the HCI principle – requirements. Consistency is explained on how the user interacts with the interface. It does not mean that the interface must look the 5. Conclusions and Recommendations same or must behave the same in all applications, but rather, Mobile phone users have a specific set of characteristics consistency is seen in the manner of doing things or in they prefer to have from mobile phones and consider behaving with different applications. It means that the user consistency as the primary characteristic. The design does not have to be forced to learn new techniques in principles of mobile developers adhere to the HCI principles. interacting with the application. The concept of consistency However, mobile phone users focus on few of those HCI can be seen on the labels and features of the interfaces. The principles, namely: consistency, synthesizability and same icons behave similarly or perform the same tasks substitutivity. The design of the mobile device is a regardless of the interface. The “x” character at the top of combination of the user-experience and HCI Principles. every window consistently means cancel.

Based on the findings and conclusions of the study, it is University Library, 2007. http://arxiv.org/ftp/arxiv/papers recommended that a study to explore the prioritization of the /0707/0707.3638.pdf. HCI principles as implemented by the mobile phone 12. Challenges in Human-Computer Interaction Design for developers be conducted to specifically determine the effect Mobile Devices. Huang, Kuo-Ying. San Francisco, USA: of a specific design principle for a certain product. This will WCECS, 2009. Proceedings of the World Congress on pave way for the differentiation of design principles Engineering and Computer Science. applicable to hardware or software. 13. Investigating the Effectiveness of Tactile Feedback for Mobile developers should make the HCI principle – Mobile Touchscreens. Hoggan, Eva, Brewster, Stephen recoverability, be more evident in their devices as this A. and Johnston, Jody. Florence, Italy: ACM, 2008. 978- principle is applied primary to software and secondary to 1-60558-011-1/08/04. hardware, which should not be the case. 14. Feel-Good Touch: Finding the Most Pleasant Tactile Similar study should be conducted for mobile Feedback for a Mobile Touch Screen Button. Oskinen, applications, such as games and customized apps to find out Emilia K., Kaaresoja, Topi and Laitinen, Pauli. Chania, whether or not the applications available in the store match Crete, Greece: ACM, 2008. 978-1-60558-198-9/08/10. the HCI design principles. Similar study can also be done to evaluate websites and student projects and come up with a set 15. Personalization and Visualization on Handheld Devices. of metrics to ensure the appropriateness of the design. Zhang, Dongsong, et al., et al. Dijon, France: ACM, 2006. 1-59593-108-2/06/0004. 6. References 16. Visualizing Locations of Off-Screen Objeccts on Mobile 1. The World in 2011: ICT Facts and Figures. [Online] Devices: A Comparative Evaluation of Three http://www.itu.int/ITU-/ict/facts/2011/material/ICTFacts Approaches. Burigat, Stefano, Chittaro, Luca and Figure2011.pdf. Gabrielli, Silvia. Helsinki, Finland: ACM, 2006. 1- 2. Mobile Subscribers Worldwide. [Online] [Cited: 59593-390-5/06/0009. December 16, 2012.] http://mobithinki ng.com/mobile- 17. Advanced Power and Thermal Management for Low- marketing tools/latest-mobile-stats/a#subscribers. Power, High-Performance Smartphones. Jung, HWisung. 3. Mobile Phone Users Worldwide. [Online] http://www. California, USA: ACM, 2012. 978-1-4503-1249-3/12/07. emarketer.com/Article/SmartphoneUsersWorldwideWill- 18. Barrel Menu: A New Mobile Phone Menu for Feature Total-175-Billion-2014/1010536 Rich Devices. Foster, Greg and Foxcroft, Terence. Cape 4. Mobile Economy 2015. [Online] http://gsmamobile Town, South Africa: ACM, 2011. 978-1-4503-0878- economy.com/GSMA_Global_Mobile_Economy_Report 6/11/10. _2015.pdf 19. Mobile Web Browsing: Usability Study. Shrestha, Sujan. 5. Improvements in Cellphone Technology. [Online] [Cited: Singapore: ACM, 2007. 978-1-59593-819-0. December 16, 2012.] http://www.eHow.com/about_ 20. Systems and software engineering -- Systems and 5542192_improvements-cell-phone-technology.html. software Quality Requirements and Evaluation (SQuaRE) 6. Mobile Trends. [Online] [Cited: December 16, 2012.] -- System and software quality models. ISO/IEC http://ezinearticles.com/?Follow-the-Mobile-Trends- 25010:2011. https://www.iso.org/obp/ui/#iso:std:iso- With-Mobile-Application-Development&id=7421722. iec:25010:ed-1:v1:en 7. Mobile Interaction. [Online] [Cited: December 16, 21. Quality Attributes. [Online] https://msdn.microsoft. 2012.] http://en.wikipedia.org/wiki/Moile_Interaction. com/en-us/library/ee658094.aspx# Performance 8. Human Computer Interaction. [Online] [Cited: December 22. Quality Model. [Online] http://en.wikipedia.org/wiki/ 16, 2012.] http://en.wikipedia.org/wiki/Human- ISO/IEC_9126 Computer_Interaction. 23. Design Principles. [Online] https://digitalcooings. 9. User Experience Design. [Online] [Cited: December 16, wordpress.com/ 2010/04/13/apples-hci-product-design- 2012.] http://www.montparnas.com/articles/what-is-user- secrets/ experience-design/comment-page-10. 24. iCloud Storage and Backup Overview. [Online] 10. Pearson Student Mobile Device Survey 2014. May 9, https://support.apple.com/kb/PH12519?locale=en_US&vi 2014. http://www.pearsoned.com/wp-content/uploads/ ewlocale=en_US Pearson-K12-Student-Mobile-Device-Survey-050914- PUBLIC-Report.pdf 11. Review and Analysis of Human Computer Interaction (HCI) Design Principles. Hinze-Hoare, V. s.l.: Cornell