1 Introduction

With the popularization of touchscreen smartphones and the development of multi-touch technologies, interactive gestures which conforming to the daily habits of users can directly interact with touchscreen smartphones and interaction between users and touchscreen phones become more natural and convenient [1]. The mounting number of smartphone R&D institutions begin to study the relationship between the touchscreen phone interactive operation and the user experience. How to make the user experience better while operating the touchscreen phone is a hot research topic [2].

In fact, which perceivable indicators of interactive operation performance can be directly perceived by users, how the effect of different tasks and different gestures on user perception, and what kind of perceivable preferences do users have for different types of apps are the foci of this research.

These studies help developers optimize the apps by exploring the user’s preference of perceivable indicators in different types of apps, which improve the user experience when they using a smartphone.

2 Related Research

2.1 Smartphone Interactive Operation Performance

The interactive operation performance of smartphone refers to the performance of users feeling when they operate a smartphone. The performance is affected by the hardware and software of the smartphone. There is a certain gap between interactive operation performance and preset performance. The better the hardware and software, the smaller the gap.

2.2 User Perception

Interactive perception refers to user expectations for interactivity and their subjective satisfaction with interactivity [3]. The interactive process of the user with the smartphone is the process of control and feedback [4]. Users control screen by using gestures, and give instructions to the smartphone, and then, smartphone give feedback to the user. After the user receives the feedback, the user can experience the interactive operation performance of the smartphone. This experience is called the smartphone interactive operation performance perception.

The research of this paper is aimed at sensitive users who have more demand for smartphone interactive operation performance and they are adept at expressing their needs. If a certain indicator can satisfy the sensitive user, can satisfy the needs of quite a few users.

2.3 The Overall Perceivable Indicators of Smartphone Interactive Operation Performance

Li explored that a good user experience is achieved with things such as user perceivable Coherence, Responsiveness, Smoothness, and Accuracy [5]. Coherence shows the ability of smartphone continuously feedback when the user continuously controls the phone. Coherence has a wide range of evaluation, includes assessing the lag distance between the fingertips and the dragged object (not only an icon but also any objects that can be dragged) in the screen. It also evaluates whether the user operation is consistent with the controlled objects, such as the angle difference between the tilting controlled water flow and the device inclination angle [5]. Nevertheless, the research of this paper is based on the interactive operation of the touchscreen phone. It only studies the performance of the dragged object can be synchronously moved with fingertip [6]. Li Proposed that the responsiveness can evaluate the time between an input being delivered to the device and device showing visible response [7]. Chu proposed that the smoothness evaluates how smooth graphics transition on the screen [8].

Nowadays, due to advanced technology, making the accuracy of smartphones greatly improved, and the accuracy has little impact on user experience [9]. Therefore, the research of this paper focuses on the user perceivable Coherence, Responsiveness, Smoothness, and we call these 3 indicators are the overall perceivable indicators of smartphone interactive operation performance (see Fig. 1).

Fig. 1.
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The overall perceivable indicators of smartphone interactive operation performance.

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Although these three indicators represent the user’s overall perception for smartphone interactive operation performance, they are not linked with specific interaction scenarios in the interaction chain. The interaction scenario means that the process of users operate smartphone to achieve the specific task by using gestures. In the process of interaction, the same task can be mapped to a variety of gestures, and the same gesture can also be mapped to different tasks. Therefore, when we use different gestures to fulfill different tasks, the perception of the user on the mobile operation performance is different. For instance, for responsiveness, there is a perceivable difference between the response time of opening the application and closing the application. When the user taps the icon to open the app, hoping the phone to quickly enter the main page, and have enough time for other operations. Therefore, users have less patience under such circumstances. However, after the task is accomplished, the user intends to exit the application. At this time, the user has no specific operation target in the app, so they have more patience under the response time of closing the application. Therefore, it is necessary to combine tasks and gestures to get the set of perceivable indicators based on the overall perceivable indicators.

This paper is organized as follows: Sects. 3 and 4 provide an overview of our study and Sect. 5 discusses the results of our study and provides useful suggestions for the soft developer; finally, Sect. 6 presents the conclusion and future work.

3 Study1: The Perceivable Indicators Set of Smartphone Interactive Operation Performance

3.1 Smartphone Interactive Operation Tasks and Smartphone Interactive Gestures

Based on the application of the smartphone’s own and download, there are 10 common tasks: open the application, enter the child page, popup, switch among sibling pages, feedback on input, return to the parent page, exit the application, move the picture or icon, zoom in/out and rotate, view page [10].

On four platforms, iOS, Android, Palm OS, and Windows, there are 7 common gestures, including “Tap” and “Swipe”. “Tap” includes: “Tap”, “Double-Tap”, “Press”. “Swipe” includes: “Swipe” and “Drag”. “Drag” includes “Single-finger Drag”, “Two-finger Pinch/Spread” and “Two-finger Rotate” [11, 12].

3.2 The Perceivable Indicators Set of Smartphone Interactive Operation Performance

Based on 3 overall perceivable indicators, combining with 10 tasks and 7 gestures. We initially obtained 26 initial perceivable indicators. The following Table 1 is about the process of how we get the 26 initial perceivable indicators: “A” shows the perceivable indicators of Coherence. “B” shows perceivable indicators of Responsiveness. “C” shows the perceivable indicators of Smoothness. Under the overall perceivable indicators, not every gesture and task can be combined to derive a specific perceivable indicator, on account of the user’s operating habits and the definition of the three overall perceivable indicators. For example, in “1. Tap–1. Open the application”, there is no specific perceivable indicator can be obtained with coherence, because based on the definition of coherence, we find that coherence is associated with drag, nothing to do with tap, and the user does not open the application by dragging.

Table 1. The initial perceivable indicators of smartphone interactive operation performance.
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Since there are repeated indicators in the 26 initial perceivable indicators, the Delphi Method was used to integrate and screen perceivable indicators [13]. By several rounds of consultation and feedback, 15 smartphone interaction experts integrated the 26 initial perceivable indicators into 21. Finally, the following Table 2 shows the set of perceivable indicators of smartphone interactive operation performance.

Table 2. The set of perceivable indicators of smartphone interactive operation performance
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4 Study2: The Typical Apps of Perceivable Indicators in Smartphone Interactive Operation Performance

According to study1, we got 21 perceivable indicators, but we found that users have perceivable difference of smartphone interactive performance in different apps when they using apps. And some users have more demand for smartphone interactive operation performance and are adept to expressing their needs. Therefore, we designed questionnaire to screen sensitive users and organized sensitive users into the focus group to explore the relationship between the perceivable indicators and the typical apps.

4.1 Sensitive Users

“The user experience evaluation questionnaire of smartphone interactive operation performance” includes “basic information” and “sensitive user screening scale”. “The sensitive user screening scale” comprises 1. “The attention ranking of smartphone interactive operation performance” 2. “The satisfaction ranking of the smartphone”. Users were asked to rate the approval ranking of each question. The approval ranking is divided into five levels: strongly disagree, disagree, neither agree nor disagree, agree, strongly agree, which correspond to the 1,2,3,4,5 points. Two scales contain 16 topics, with a total of 65 points, and the users who have scored in the top 20% are regarded as sensitive users.

368 online questionnaires were obtained, including 344 valid questionnaires and 24 invalid ones. There are 168 men and 176 women, and the proportion of men and women is nearly the same. According to market positioning (the models and price of the smartphone), 9 users who use lower-end phones were excluded among 69 sensitive users. Other 60 users are sensitive users, accounting for 17.4% of the total number of users (see Fig. 2).

Fig. 2.
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The proportion of sensitive users accounted for the total users.

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These sensitive users’ average age is 23 years old, 85% of them use the iOS system. They spend more than 4 h on smartphone every day, and they buy a new mobile phone once 6 months to once one year. Sensitive users often use the higher-end smartphone. They are familiar with the operation of the smartphone and often take the initiative to seek more convenient interactive operation mode. They are concerned about whether the smartphone interaction performance is satisfactory.

4.2 Typical Apps

Twenty-four sensitive users (12 Males, 12 Females) participated in the focus group. Users were divided into 4 groups to fulfill the following two tasks: 1. For each perceivable indicator, choose the most important 1–3 apps from your smartphone (both the system apps or the downloaded ones) 2. Describe the reason for your choice. In the course of the experiment, each group with a camera to record their oral expression. The data as shown (see Fig. 3).

Fig. 3.
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The choices condition of applications under each perceivable indicator. (Color figure online)

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The number of choices from yellow (less) to green (more). Colors are normalized by row, with green indicating each application’s maximum number of indicators, and white indicating each app’s minimum.

Twenty-nine apps are selected by users. In accordance with the Android market and the iPhone app store, 29 apps are grouped into 11 categories: Social, Reading, Photography, Map, Shopping, Note, Music, Brower, App Management, Education, Finance. Social apps are the most plentiful, which have 5 apps, including WeChat, Weibo, QQ, Zhihu, Address book. The total number of perceivable indicators in Social app is the most, followed by Photography, Shopping, etc. It can be seen that users are sensitive to the interactive operation performance of Social apps.

In Music and App Management, the number of app choices of each perceivable indicator is basically below 3, indicating that sensitive users have low attention to the perceivable indicators of these two types of apps.

5 Discussion

Coherence. For Drag Coherence, Meitu and Baidu Map have the maximum number of choices. Users usually use Meitu to retouch pictures. For instance, they use the dragging of gesture to pat off black eyes and thin face, etc. On the Baidu Map, users drag the map to find a location. For Zoom Coherence, Photography and Map are crucial, because users usually pinch/spread the picture and map by two fingers. However, Social and Taobao are also significant, because there are many pictures in these apps. Users often zoom in/out pictures and drag the list of pages for viewing. Input Coherence has the minimum number of apps, only 25, but the number of apps reached 64 for The Response Time of Inputting. Through user interview, it is found that the number of apps in Input Coherence is less because sensitive users rarely use the hand-written input method, and they use the keyboard input method instead. Keyboard input is more important for the Responsiveness. Sensitive users are mostly young, while people who use the hand-written input method are middle-aged and elderly people. If developing a smartphone or apps for the elderly, the importance of Input Coherence will increase.

In general, Albums, Meitu, Baidu Map are important to the Coherence.

Responsiveness. The Response Time of Opening is the most important, following the Response Time of Entering and the Response Time of Inputting, etc. Sensitive users said they often pay attention to the response time. If there are many apps running and the smartphone is used for a long time, the response time would be increased. The number of apps of four indicators in Responsiveness is above 60, illustrating that users have strong awareness for the Responsiveness. The apps of Responsiveness are mostly distributed in Social, Photography, Shopping. In Weibo, Wechat, Camera, sensitive users are most concerned about the Response Time of Opening.

Weibo, Wechat, and Camera are important to the responsiveness.

Smoothness. The indicator that have the maximum number of the apps is the Smoothness of Swiping Up or Down, following the Smoothness of Swiping Left or Right and the Smoothness of Popup. On the Smoothness of Swiping Up or Down, Social, Reading, and Taobao are important because they have long pages, and users require swiping pages to view content. As for The Smoothness of Swiping Left or Right, it is applicable to the apps which have lots of sibling pages. On the Smoothness of Popup, Social and Browser are important, for the reason that users often use searching, typing and other functions, which will pop search box and keyboard.

Weibo, Zhihu, Taobao are important to the smoothness.

6 Conclusion and Future Work

This paper explores the specific perceivable needs of users for the smartphone interactive operation performance, and get 21 perceivable indicators. Coherence: Drag Coherence, Zoom Coherence, Rotate Coherence, Input Coherence. Responsiveness: The Response Time of Opening, The Response Time of Exiting, The Response Time of Entering, The Response Time of Returning, The Response Time of Popup, The Response Time of Inputting, The Response Time of Switching, The Response Time of Swiping, The Response Time of Zooming Page by Double Taps. Smoothness: The Smoothness of Opening, The Smoothness of Exiting, The Smoothness of Entering, The Smoothness of Returning, The Smoothness of Popup, The Smoothness of Swiping Left or Right, The Smoothness of Swiping Up or Down, The Smoothness of Zooming Page by Double Taps.

The typical apps of the Overall Perceivable Indicators. Coherence: Albums, Meitu, Baidu Map. Responsiveness: Weibo, Wechat, and Camera. Smoothness: Weibo, Zhihu, Taobao. These typical apps provide a basis for the study of the user’s perception of smartphone interactive operation performance in different Apps.

For future studies of this research, there are numerous works we need to do on the smartphone interactive operation performance with user perception.

  • We will use the perceivable indicators and typical apps derived from this paper. Using electrophysiological equipment and eye tracker to finish the Coherence, Responsiveness, and Smoothness of the experiments.

  • In combination with the change of physiology and eye movement, the reliability of the user`s MOS scores for will be verified. The data model and equation of each perceivable indicator will be established by SPSS. Finally, the overall model of the smartphone interactive operation performance perception will be obtained by calculating the weight of Coherence, Responsiveness, and Smoothness.