Keywords

1 Introduction

1.1 Background

If there is a behavior most Chinese today would do in their daily life, that would definitely be the use of smartphone. Indeed, according to Statista, in 2017 China has around 663.37 million smartphone users, a number greater than the whole population of USA and Brazil combined. The widespread application of smartphone has brought the whole Chinese nation into an unprecedented social media era when interpersonal communication has been dramatically facilitated regardless of space and time limits.

To support such frequent and effective communication, many smartphone-based social media tools are playing key roles. Take the most successful one: WeChat as an example, it is a mobile instant messaging (text and voice) communication service invented by Tencent (腾讯) in 2011. WeChat bridges the communication between millions of users by means of text messages (SMS), hold-to-talk voice messages, group chat, video conferencing, free voice call, location sharing, contact sharing and Moments (photo and video sharing). Among these communication methods, text message is undoubtedly the most widely and frequently used function. Consequently, the need for a convenient way to input Chinese text messages becomes increasingly important [1].

1.2 Pinyin Input Method

To edit a piece of Chinese message on a smartphone, Chinese input methods are always needed. Basically they are categorized into two types, as seen in Table 1:

Table 1. Examples of some famous Chinese input methods
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1. Pronunciation based input method; 2. Structure based input method.

Among various Chinese input methods, Pinyin input method is apparently the most popular means. In 2014, 76.7% of Chinese smartphone users choose Pinyin input method [2]. Pinyin (Pinyin Romanization (https://en.wikipedia.org/wiki/Romanization)) is a system that transcribes the pronunciation of Chinese characters into a string of Roman letters [3]. The mechanism of Pinyin input method is that by typing Pinyin, computer will automatically recognize and match all possible corresponding Chinese characters, phrases, and sentences for user. For example, one wants to input “兽医” (veterinary) on a smartphone. First, he needs to type the Pinyin of 兽医, which is “shouyi”. Then smartphone will list a cluster of candidate Chinese characters and phrases that are pronounced as “shouyi”, such as:

手艺 craftsmanship; 受益 benefit; 收益 earnings; 兽医 veterinary; 寿衣 shroud.

Finally, a user completes the texting by just tapping characters “兽医” (see Fig. 1).

Fig. 1.
figure 1

An example of how to input Chinese character with Pinyin input method (T9 Pinyin keyboard).

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1.3 Research Question

Pinyin input method was born to confront with a sheer challenge: Modern Chinese has merely less than 500 pinyin syllables that disproportionately represent over 6,000 commonly-used Chinese characters, which leads to serious ambiguities for pinyin-to-character mapping [4]. Therefore, lasting efforts are still required both from academia and industry to continuously improve the efficiency of pinyin-to-character conversion.

The advent and widespread of touchscreen technology revolutionarily change human behavior of texting. While typing on a physical QWERTY keyboard is one thing, typing with a virtual keyboard on a smartphone touchscreen is another story. Instead of using all ten fingers, tapping on a soft keyboard only requires one or two thumbs. In this sense, people may optimistically believe that this radical change facilitates user’s typing behavior since no touch typing would ever be needed. However, scientific study has found that the speed and accuracy of Pinyin typing would be significantly reduced when using a smartphone virtual keyboards due to the difficult nature of tapping small targets on virtual keys [5]. Hence, more rigorous research is needed to seek optimal layout design of a Pinyin input method interface.

The fact that smartphone-based Pinyin input method use is so widespread in today’s China and no systematic work has been done to review related academic research makes the present research extremely important and motivated. By reviewing the latest academic works, the present study tries to explore what academic efforts have been spent:

  1. 1.

    To improve the functionality and usability of Pinyin input method?

  2. 2.

    To better understand user behaviors during the interaction with Pinyin input method interface?

As a result, a summary in forms of tables will be proposed as a guideline for future Pinyin input method development.

2 Methodology

2.1 Literature Criteria

Academic studies that discussed smartphone-based Chinese Pinyin input method (The input of Pinyin is achieved by finger-tapping on virtual keyboard based on touchscreen). Candidate publications are set to be from 2005, in forms of either peer review journal articles, conference proceedings, reports or books. They can be both written in Chinese and English.

2.2 Keywords

Pinyin input method, smartphone, touchscreen, interaction design, layout, usability.

3 Results

Initially, thirty publications in both English and Chinese have been found from the following online database: Google Scholar, Springer, ELSEVIER, IEEE Xplore Digital Library and Research Gate. After carefully sieving, 13 articles have been eventually selected and a summary covering their basic information such as author, year, problem, solution, result has been established in the form of Table 2, as shown below.

Table 2. Summary of literature review
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4 Discussion

For convenience, two tables have been developed to separately discuss the literature review result Table 3 in two aspects: functional characteristics and design characteristics.

Table 3. Discussion regarding functions
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4.1 User Behavior

Analyzing user behavior provides novel perspective and is thus helpful in improving user experience and performance of Pinyin input method [17]. The result in this study reveals that users desire a Pinyin input method that could, to maximum extent, lesson human’s physical (typing, visual searching) and mental (recognizing) loads and if better, could further understand the meaning and the logic of human language and thus be able to intelligently assist human in texting (Table 4).

Table 4. Discussion regarding interface design
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5 Conclusion

The present study conducted a literature review regarding smartphone-based Pinyin input method. While thirty publications have been found, thirteen of them was eventually selected and summarized. As a result, it is found that much efforts have been implemented to enhance Pinyin-to-character conversion by integrating more powerful algorithm addressing issues over error detection and correction. For design issue, lots of work has been done to optimize visual keyboard layout to improve typing speed and accuracy. In the last, suggestions for future work such as strengthening prediction function, introducing size-adjustable keyboard and innovative typing methods have been proposed.