Investigating Smartphone Touch Area with One-Handed Interaction: Effects of Target Distance and Direction on Touch Behaviors

ABSTRACT

The objective of this study was to investigate the touch area that can be comfortably reached by the thumb during one-handed smartphone interaction. To achieve the research objective, we introduced the concept of natural thumb position when designing a tapping task and conducted an user experiment. The independent variables were the target distance and direction from the natural thumb position, and the three dependent variables were the task performance, information throughput, and touch accuracy. The results showed that participants performed the task comfortably in the diagonal direction between the upper right and the lower left side of the screen. The task performance deteriorated as the target distance increased, especially at 45 mm or more. The touch accuracy was measured using X- and Y-coordinates data. Participants touched the left side of the target center, except near the proximal area of the hand. They also touched the points above the center of the target in the upper screen area and points below the center of the target in the lower screen area. The findings of this study provided insights for designing a smartphone touch interface considering the comfortable touch areas of one-handed interaction.     

Touchable area: An empirical study on design approach considering perception size and touch input behavior

As the use of mobile touch devices continues to increase, distinctive user experiences can be provided through a direct manipulation. Therefore, the characteristics of touch interfaces should be considered regarding their controllability. This study aims to provide a design approach for touch-based user interfaces. A derivation procedure for the touchable area is proposed as a design guideline based on input behavior. To these ends, two empirical tests were conducted through a smart phone interface. Fifty-five participants were asked to perform a series of input tasks on a screen. As results, touchable area with a desirable hit rate of 90% could be yielded depending on the icon design. To improve the applicability of the touchable area, user error was analyzed based on omission-commission classification. The most suitable design had a hit rate of 95% compared to 90 and 99%. This study contributes practical implications for user interaction design with finger-based controls.Relevance to industryThis research describes a distinctive design approach that guarantees the desired touch accuracy for effective use of mobile touch devices. Therefore, the results will encourage interface designers to take into account the input behavior of fingers from a user-centered perspective.     

Performance effects of reduced proprioceptive feedback on touch typists and casual users in a typing task

This study examined performance and acceptance effects of lack of kinesthetic and tactile feedback from the keyboard in a typing task with two subject groups of differing skill level: touch typists and casual users. Subjects' objective performance (e.g., speed, accuracy, throughput) and subjective acceptance (questionnaire) was evaluated for both a conventional full travel keyboard and a prototype piezoelectric flat keyboard which lacked familiar kinesthetic and tactile feedback. Any performance decrement present with the flat keyboard was expected to diminish with practice for the touch typists due to transfer and adaptation of typing skills. Performance for both subject groups was significantly higher with the conventional keyboard and touch typists' performance was more adversely affected by the flat keyboard than casual users'. No performance improvement with practice was found for one subject group relative to the other or for one keyboard relative to the other. It was concluded the touch typists were unable to adapt to the unusual feedback conditions present with the piezo-electric fiat keyboard.     

Notebook input devices put to the age test: the usability of trackpoint and touchpad for middle-aged adults

In two experiments, the usability of input devices integrated into computer notebooks was under study. The most common input devices, touchpad (experiment 1) and trackpoint (experiment 2) were examined. So far, the evaluation of mobile input devices has been restricted to younger users. However, due to ongoing demographic change, the main target group of mobile devices will be older users. Therefore, the present study focused on ageing effects. A total of 14 middle-aged (40–65 years) and 20 younger (20–32 years) users were compared regarding speed and accuracy of cursor control in a point-click and a point-drag-drop task. Moreover, the effects of training were addressed by examining the performance increase over time. In total, 640 trials per task and input device were executed. The results show that ageing is a central factor to be considered in input device design. Middle-aged users were significantly slower than younger users when executing the different tasks. Over time, a significant training effect was observed for both devices and both age groups, although the benefit of training was greater for the middle-aged group. Generally, the touchpad performance was higher than the trackpoint performance in both age groups, but the age-related performance decrements were less distinct when using the touchpad.     

Notebook input devices put to the age test: the usability of trackpoint and touchpad for middle-aged adults

In two experiments, the usability of input devices integrated into computer notebooks was under study. The most common input devices, touchpad (experiment 1) and trackpoint (experiment 2) were examined. So far, the evaluation of mobile input devices has been restricted to younger users. However, due to ongoing demographic change, the main target group of mobile devices will be older users. Therefore, the present study focused on ageing effects. A total of 14 middle-aged (40-65 years) and 20 younger (20-32 years) users were compared regarding speed and accuracy of cursor control in a point-click and a point-drag-drop task. Moreover, the effects of training were addressed by examining the performance increase over time. In total, 640 trials per task and input device were executed. The results show that ageing is a central factor to be considered in input device design. Middle-aged users were significantly slower than younger users when executing the different tasks. Over time, a significant training effect was observed for both devices and both age groups, although the benefit of training was greater for the middle-aged group. Generally, the touchpad performance was higher than the trackpoint performance in both age groups, but the age-related performance decrements were less distinct when using the touchpad.     

Augmenting Tactile 3D Data Navigation With Pressure Sensing

We present a pressure‐augmented tactile 3D data navigation technique, specifically designed for small devices, motivated by the need to support the interactive visualization beyond traditional workstations. While touch input has been studied extensively on large screens, current techniques do not scale to small and portable devices. We use phone‐based pressure sensing with a binary mapping to separate interaction degrees of freedom (DOF) and thus allow users to easily select different manipulation schemes (e. g., users first perform only rotation and then with a simple pressure input to switch to translation). We compare our technique to traditional 3D‐RST (rotation, scaling, translation) using a docking task in a controlled experiment. The results show that our technique increases the accuracy of interaction, with limited impact on speed. We discuss the implications for 3D interaction design and verify that our results extend to older devices with pseudo pressure and are valid in realistic phone usage scenarios.     

Nomadic Input on Mobile Devices: The Influence of Touch Input Technique and Walking Speed on Performance and Offset Modeling

In everyday life, people use their mobile phones on-the-go with different walking speeds and with different touch input techniques. Unfortunately, much of the published research in mobile interaction does not quantify the influence of these variables. In this article, we analyze the influence of walking speed, gait pattern, and input techniques on commonly used performance parameters like error rate, accuracy, and tapping speed, and we compare the results to the static condition. We examine the influence of these factors on the machine learned offset model used to correct user input, and we make design recommendations. The results show that all performance parameters degraded when the subject started to move, for all input techniques. Index finger pointing techniques demonstrated overall better performance compared to thumb-pointing techniques. The influence of gait phase on tap event likelihood and accuracy was demonstrated for all input techniques and all walking speeds. Finally, it was shown that the offset model built on static data did not perform as well as models inferred from dynamic data, which indicates the speed-specific nature of the models. Also, models identified using specific input techniques did not perform well when tested in other conditions, demonstrating the limited validity of offset models to a particular input technique. The model was therefore calibrated using data recorded with the appropriate input technique, at 75% of preferred walking speed, which is the speed to which users spontaneously slow down when they use a mobile device and which presents a trade-off between accuracy and usability. This led to an increase in accuracy compared to models built on static data. The error rate was reduced between 0.05% and 5.3% for landscape-based methods and between 5.3% and 11.9% for portrait-based methods.     

Investigation of Icon Design and Touchable Area for Effective Smart Phone Controls

As the full‐touch screen is being implemented in more smart phones, controllability of touch icons need to be considered. Previous research focused on recommendations for absolute key size. However, the size of tactual input on touch interface is not precisely equal to the icon size. This study aims to determine the suitable touchable area to improve touch accuracy. In addition, there was an investigation into the effect of layout (3 × 4, 4 × 5, 5 × 6, and 6 × 8) and icon ratio (0.5, 0.7, and 0.9). To achieve these goals, 40 participants performed a set of serial tasks on the smart phone. Results revealed that the layout and icon ratio were statistically significant on the user response: input offset, hit rate, task completion time, and preference. The 3 × 4 and 4 × 5 layouts were shown to have better performance. The icon ratio of 0.9 was shown to have greater preference. Furthermore, the hit rate (proportion of correct input) of touchable area was estimated through the bivariate normal distribution of input offset. The hit rate could vary, depending on the size of touchable area, which is a rectangle that yields a specific hit rate. A derivation procedure of the touchable area was proposed to guarantee the desirable hit rate. Meanwhile, the locations of the central region indicated a pattern of vertical touch and showed better performance. The users felt more difficulty when approaching the edge of the frame. The results of this study could be used in the design of touch interfaces for mobile devices.     

Older Adults’ Text Entry on Smartphones and Tablets: Investigating Effects of Display Size and Input Method on Acceptance and Performance

This study focuses on older adults’ finger-based text entry on smartphones and tablets. Thirty-two older adults entered Chinese characters with two input methods (typing and handwriting) on touch screens with four display sizes (3.5 in., 5 in., 7 in., 9.7 in.). Their performance, acceptance, preference, and errors were recorded and thus four findings were found. First, on small displays (3.5 in. and 5 in.), handwriting contributed to shorter task completion time, higher perceived ease of use, and higher usage intention than typing, but no difference was observed on large displays (7 in. and 9.7 in.). Second, there is a gap of task completion time and perceived ease of use between 5 in. and 7 in. for typing, whereas there is no gap for handwriting. Third, participants’ preference of 9.7 in. was almost the same as that of 7 in., and their preference of 7 in. was 1.5 times as strong as that of 5 in. Fourth, participants’ finger-based text entry was prone to 13 types of errors. Many of these errors were caused by the mismatch between older adults’ mental models and designers’ mental models.     

Assessing two new wearable input paradigms: The Finger-Joint-Gesture palm-keypad glove and the invisible phone clock

Text and digit entry speed of two wearable one-handed input paradigms, the Finger-Joint-Gesture palm-keypad glove and the Invisible Phone Clock, were benchmarked against traditional one-handed cellular phone keypad input in a repeated-measurement design employing 18 subjects using a 9-word sentence. No significant difference in error-corrected text entry speed (5.3 ec-wpm) was found. Digit entry speed was significantly faster (8.3 ec-wpm) and differed significantly between input paradigms. Furthermore, digit entry was fastest for the traditional cellular phone keypad and slowest for the Invisible Clock keypad. A prediction model based on Fitts' law slightly overestimated text entry speed for novice users. Another prediction model, where each movement time between successive keys was corrected for key repeat time for each specific input paradigm, predicted the experimental results more accurately. Thirteen of the subjects ranked the Invisible Phone Clock as 1^st choice. The subjects' mapping of the Ericsson cellular phone functions (YES, CLR, NO, <,> and Address Book) was not according to the designer's model, partly due to functional fixedness. The input paradigms could be suitable candidates for new fragmentised interfaces where wearability is the key issue.     

Touch a screen or turn a knob: choosing the best device for the job

Input devices enable users to interact with systems. In two experiments, we assessed whether and how task demands and user age influenced task performance for a direct input device (touch screen) and an indirect input device (rotary encoder). In Experiment 1, 40 younger (18-28 years) and 40 middle-aged to older adults (51-65 years) performed tasks using controls such as sliders, up/down buttons, list boxes, and text boxes while using a system. The optimal input device to facilitate performance was dependent on the task being performed and the age of the user. In Experiment 2, touch screen use was assessed for 20 younger (19-23 years) and 20 older adults (51-70 years). Task demands were manipulated through button size, movement distance, direction, and type of movement. Performance was moderated by the age of the user and by task demands. Actual or potential applications of this research include guidance for the optimal selection of input devices for different user populations and task characteristics.     

Evaluating the benefits of multimodal interface design for CoMPASS—a mobile GIS

The context of mobility raises many issues for geospatial applications providing location-based services. Mobile device limitations, such as small user interface footprint and pen input whilst in motion, result in information overload on such devices and interfaces which are difficult to navigate and interact with. This has become a major issue as mobile GIS applications are now being used by a wide group of users, including novice users such as tourists, for whom it is essential to provide easy-to-use applications. Despite this, comparatively little research has been conducted to address the mobility problem. We are particularly concerned with the limited interaction techniques available to users of mobile GIS which play a primary role in contributing to the complexity of using such an application whilst mobile. As such, our research focuses on multimodal interfaces as a means to present users with a wider choice of modalities for interacting with mobile GIS applications. Multimodal interaction is particularly advantageous in a mobile context, enabling users of location-based applications to choose the mode of input that best suits their current task and location. The focus of this article concerns a comprehensive user study which demonstrates the benefits of multimodal interfaces for mobile geospatial applications.     

Visual Impairments and Mobile Touchscreen Interaction: State-of-the-Art,Causes of Visual Impairment,and Design Guidelines

ABSTRACT

This article identifies, catalogues, and discusses factors that are responsible for causing visual impairment of either a pathological or situational nature for touch and gesture input on smart mobile devices. Because the vast majority of interactions with touchscreen devices are highly visual in nature, any factor that prevents a clear, direct view of the mobile device’s screen can have potential negative implications on the effectiveness and efficiency of the interaction. This work presents the first overview of such factors, which are grouped in a catalogue of users, devices, and environments. The elements of the catalogue (e.g., psychological factors that relate to the user, or the social acceptability of mobile device use in public that relates to the social environment) are discussed in the context of current eye pathology classification from medicine and the recent literature in human–computer interaction on mobile touch and gesture input for people with visual impairments, for which a state-of-the-art survey is conducted. The goal of this work is to help systematize research on visual impairments and mobile touchscreen interaction by providing a catalogue-based view of the main causes of visual impairments affecting touch and gesture input on smart mobile devices.     

Seamless handover integrated solution for video transmission over proxy mobile IPv6 in a micro mobility domain

Seamless communication is becoming one of the most important issues for the next generation of mobile and wireless networks. In this context, seamless is referred to users that are free to roam around different networks and at the same time stay connected without any disturbance to the ongoing session during the handover process from one network to another. The handover process between these networks spawns long delay or latency, high packet loss, and fewer throughputs which may degrade the performance of real-time applications during the handover process. Therefore, in order to resolve these problems, a new protocol has been proposed by Network-based Localized Mobility Management working group of Internet Engineering Task Force under network-based mobility management protocol. Although, this protocol managed to minimize the problems related to network switching, it still suffers several drawbacks during the handover process especially when the movement speed of mobile user is high. In this paper, we present a new approach which is a network-based mobility management protocol that aims to reduce the lengthy handover latency, jitter, high packet loss, and increase throughput and the performance of video transmission during the high speed mobility. The proposed approach namely Seamless Handover Integrated Solution consists of mobility prediction method, a set of Internet Control Message Protocol version 6 (ICMP6) messages which are effective in terms of handover optimization.     

Comparison of Cognitive Modeling and User Performance Analysis for Touch Screen Mobile Interface Design

The aim of this study is to analyze and comparatively evaluate the usability of touch screen mobile applications through cognitive modeling and end-user usability testing methodologies. The study investigates the accuracy of the estimated results of a cognitive model produced for touch screen mobile phone interfaces. A mobile wallet application was chosen as the mobile software. The CogTool modeling tool was used as the cognitive modeling method. Eight tasks were determined and user tests were conducted in a usability laboratory with 10 participants. The tasks were compared on the basis of step time and total task completion time. This study reveals that CogTool gives approximate estimations with actual user performance on touch screen mobile phone application interfaces. However, if there are special cases in the tasks such that users are very accustomed to the steps or decision-making that is involved in the tasks, the “Think Operation” in CogTool should be modified.     

Directional bias in scrolling tasks: a study of users' scrolling behaviour using a mobile text-entry strategy

Mobile devices with limited interaction controls often employ cyclic scrolling for retrieval tasks. In this paper the scrolling behaviour of users entering text using a tree-key input technique based on two-phase cyclic character scrolling is studied. The results show that users have a tendency to scroll more from left-to-right than from right-to-left. However, users do also use the right-to-left functionality to both speed up their text entry task by choosing the shortest path and to make navigational corrections, suggesting that it is appropriate to provide bidirectional scrolling functionality in user interfaces on constrained mobile devices. In situations where a device architect is constrained to providing only unidirectional scrolling, the results suggest that a right-directional design is preferred over a left-directional design.     

Efficient model of Korean graphemes based on a smartphone keyboard

Smartphones are becoming more advanced, and the use of touch input is increasing. Therefore, various keyboards can be implemented in smartphones. Unlike the button input method, the touch input method can have non-fixed keys that can be freely arranged. Many users are thus interested in the touch input method. In this paper, we propose a Korean grapheme model called ‘Auto Toggle’ by using auto switching between consonants and vowels of Hangul. Also, Auto Toggle is designed and implemented based on the Android platform. Finally, we describe the results of a performance evaluation for the number of buttons pushed for each single syllable of Hangul compared with conventional methods. Additionally, Auto Toggle results in a rapid improvement on typing speed with respect to sentence generation.     

Does the Hand Anthropometric Dimension Influence Touch Interaction?

Amid the increasing popularity of smartphones fitted with touch screens, many studies have been conducted on touch screen input methods. In contrast to standardized stylus pens, the size and anthropometric features of the fingers can be vastly different depending on the person. These features significantly impact the touch screen’s usability for an individual. In this paper, the relationship between the anthropometrical dimensions of the thumb (i.e., length, breadth) and touch task performance was analyzed. Based on the results, subjects with relatively longer fingers required more time on average to complete the task. However, no correlation was evident between the thumb length and number of errors, or among the thumb breadth, task completion time, and error frequency. The results of this study are expected to be useful in the development of a mobile interface that considers the specific features of the user’s thumb.     

Experimental Evaluations of the Twiddler One-Handed Chording Mobile Keyboard

The HandyKey Twiddler? is a one-handed chording mobile keyboard that employs a 3 × 4 button design, similar to that of a standard mobile telephone. We present a longitudinal study of novice users' learning rates on the Twiddler. Ten participants typed for 20 sessions using 2 different text entry methods. Each session was composed of 20 min of typing with multitap and 20 min of one-handed chording on the Twiddler. We found that users initially had a faster average typing rate with multitap; however, after 4 sessions the difference became negligible, and by the 8th session participants typed faster with chording on the Twiddler. Five participants continued our study and achieved an average rate of 47 words per minute (wpm) after approximately 25 hr of practice in varying conditions. One participant achieved an average rate of 67 wpm, equivalent to the typing rate of the 2nd author, who has been a Twiddler user for 10 years.We analyze the effects of learning on various aspects of chording, provide evidence that lack of visual feedback does not hinder expert typing speed, and examine the potential use of multicharacter chords (MCCs) to increase text entry speed. Finally, we explore improving novice user's experience with the Twiddler through the use of a chording tutorial.     

Interacting with mouse and touch devices on horizontal interactive displays

This article presents and discusses findings on collaborative interaction on horizontal interactive displays using touch and mouse input devices. Tabletop interaction environments are suitable for small computer-supported group collaboration, and usually allow for concurrent interaction by multiple users. The appropriate support of interaction on horizontal interactive displays is crucial to the successful design and adoption of digital tabletops for work, education and entertainment. A study was conducted investigating interactions of users on tabletops operating with mouse and touch input devices, and shedding light on the differences and commonalities from different perspectives. This laboratory study was designed to allow for as much ecological validity and to provide good experimental control at the same time. The study builds on the standard digital puzzle, or mosaic task, by adding a hidden or implicit task, for the participants to discover and work on. Without solving the hidden task, participants were not able to solve the primary puzzle task. This approach was chosen to trigger spontaneous and natural collaborative work amongst the participants in the lab setting. The analysis of the interaction is based on system-logged interaction data, questionnaires and observations focused on the participants’ selection and usage of input devices during the task execution. The study revealed, amongst others, that participants did not change their initially preferred input device even when they became more engaged in coordination and communication with their partner during the course of the study.