Keywords

1 Introduction

Under the development and prevalence of high-tech products, people use computers, mobile phones, televisions, home appliances, and vehicles in their daily life. As the technology products are designed to bring convenience and social progress, among them, the mobile products feature the fastest development and high elimination and replacement rate. The continuous development technology can make the mobile products more compact, yet be equipped with many functions, such as audio control, online searching, listening to radio or watching TV shows, tabulation, calendar for daily planning, photographing, sending e-mail, etc. The design of interface develops from physical keys to touch screen. The development trend reveals that the previous designs were aimed to satisfy the usage habit of the masses in pursuit of convenience. As long as the device can be portable, other audio and video devices and equipment would no longer be in demand. In the design of these products, the designers added the interface suitable for the usage of the elderly, but met the problem of “over-simplicity” design, which actually presented a kind of stereotype. The designers often unselfconsciously eliminate “the elderly” from the users of high-tech devices, and propose to lower the complexity of technology devices to increase the acceptability of the group. With the advent of the aging society, relevant topics have emerged, and received attention from countries across the world. The aging tendency of society is a topic deserving attention in the course of development. The aging society is characterized by the sharp increase in the population the elderly every year, thus making the satisfaction of elderly users a top priority. Currently, when people walk on the street or wait at the bus stops, they are often using smart mobile devices, some even carry over two models at a time, which is much different from the stereotype that the elderly either take walks in parks or live alone. The elderly can use the smart mobile devices as proficiently as the young adults. Therefore, despite the increase in senior populations across the world, they have begun to use these high-tech products on a daily basis, and started intimate interaction in the usage process, thereby developing a sense of safety and reliability. In this way, they have gained autonomous right that allows them to use the personal smart mobile device independently and conveniently without being dependent on the guidance of a younger family member. They are becoming the potential users of the new technology.

This study focuses on gesture operation, proposes operation modes more suitable for the elderly, and attempts to develop an innovative gesture design method for smartphone operation gesture. This study discusses the usability of mobile phone, and reviews the existing interface design from the perspectives of the users. The usability principle is taken as the evaluation standard. Through the experiment method, the interface usage and usability in interactive operation are discussed, taken as reference for designing single-point touch interface software. At present, most smartphones adopt multiple-point touch operation. Different from past physical touch provided by the hardware interface, the operation is carried out by the gesture made by fingers directly on the screen. Without the need for press action, actions including gently knocking, long press, dragging can be performed to complete interface operation. All users must adapt to the new form of operation. Gestures are a natural and powerful tool for communication among people. Piper mentioned in the “Exploring the accessibility and appeal of surface computing for older adult health care support” that comparing the multiple-point touch device and traditional devices, the former is closer to the usage habit of users [1]. Researches on gesture operation in Taiwan and abroad mentioned that relevant gestures can be interpreted as direct and indirect touch. For the elderly, direct operation is more efficient than indirect operation. If intuitive gestures can be applied, it can shorten the time for elderly users to learn new gestures, and increase the interaction and sense of security between products and the elderly users.

2 Literature Review

Touch devices serve as standard operation interface of 3C products. They are widely applied in public facilities and transportation system (e.g., ATM, iBon multifunction machine, high-speed rail ticket machine) [2], medical health system machines in hospitals [3], and social network platform [4]. The touch operation is a design product under the concept of direct manipulation [5]. Its advantages include fast learning, better hand-eye coordination, less occupation of hardware space, and high availability in public places. However, without adjusting the hand gesture and angle of view, users may easily feel fatigue [6]. In terms of gesture control, there are a variety of technologies, which can be divided into two-dimensional gesture, which refers to the operation by using fingers or hands on touch screen, and three-dimensional gesture, which is defined as operation by using movement space in more free forms. For two-dimensional operation gesture, this study aims to develop better smartphone operation to assist the elderly in operation freely. Among relevant literature on the degradation of exercise performance of the elderly, Chaparro pointed out the doubt in the adaptability of finger operation for the elderly in the research of “Range of motion of the wrist: implications for designing computer input devices for the elderly” [7]. If the wrist joint operation is included in gesture operation, the flexibility of wrist of the elderly should be included into the evaluation, so as to determine whether a gesture suits the elderly. For various kinds of smartphones in the market, this study still doubted whether the interface gestures are suitable for the usage of the elderly. To date, relevant topics on smartphone gesture design among the middle-aged and the elderly are still rare. This study team attempts to develop innovative ways for smartphone interface gesture operation.

2.1 Cognitive Psychology of Aging

When people age, they face physical degeneration, which greatly lowers their mobility, memory, and learning ability. The changes in visual function are the most evident. Due to the diminution of vision, the elderly find it hard to see things clearly and the adaptation to brightness and acceptance of sensitivity and color are affected. The life of the elderly is therefore affected. The physical degeneration further leads to the degeneration of thinking ability and judgment. From another point of view, after the elderly retreat from the workplaces, they have less exposures to social contacts and self-improvement, which inevitably results in a relative distance from the society, as well as a gap between their real life and cognition. The influence on mentality is also on the rise. In terms of recognition, understanding and learning, the elderly are subject to degeneration of message processing as they age, such as decreased attention, narrowed recognition on time and space, lowered distinguishing ability of instant message, lowered complex information processing ability, slowed response to stimulation, which impacts the record and memory of event details. The changes in recognition of the elderly are mainly reflected in handling inductive inference, fluency in semantics and language, and figure and space concept. Those changes affect their communication effect of information reading and emotion reaction of advertisement [8]. From the point of view of social psychology, the elderly connect with the society through media, and rely on news, entertainment and message to look for familiar roles to compensate their diminishing social networks. This kind of media contact features the function of “quasi-social role” [9]. The elderly use media for the purpose of looking for happiness, killing time or pursuing leisure. They bridge the gap in social experience via media or learn new roles for self-affirmation.

2.2 Research on the Usage of Man-Machine Interaction

The intuition-based operation allows users to interact with the devices with direct fingers operation. Although it attracts elder computer users, there are still problems to be explored from the perspective of theory or practice [10]. For example, with thumb as fixing point, the index finger is used to make a loop. One typical case is that the gesture for viewing photo is intuition-based, but complex editing operations are needed, such as selection, rotation, or copy-paste become too complicated for figure gestures. McLaughlin and Charness proposed that the effect of interactive device is based on a set of precise data calculation [11]. For the elderly, choosing interactive devices that are compatible with operation mode is the key factor to ensure performance. Barker studied the use of smartphones by the elderly, and proposed eight strategies: 1) priority is given to click and slide gestures; 2) demonstration gesture; 3) enlarge touch target; 4) place the target in eye-catching places; 5) reserve enough space between targets; 6) interaction with target is to provide feedback; 7) limit text input if possible; 8) use clear font with proper size [12]. Caprani et al. found that the elderly perform better when using touch screen than other input devices [13]. Compared with other input devices, the touch screen is preferred by the elderly.

2.3 Welfare Design

With the progress in medical and technology, the elderly population is able to enjoy active social participation and independent living ability. From the perspective of technology, how to apply various technology aids to help the elderly who suffer from gradual physical degeneration to enjoy a more active, healthy, comfortable, and safe life is an important subject. In 1992, the First International Congress on Gerontechnology was held in Europe, which established research structure for enhancing technology and the aged well-being. Graafmans and Bouma from Eindhoven University of Technology of the Netherlands defined the welfare technology for the elderly as follows: based on the knowledge on aging progress, the welfare technology for the elderly is engaged in the research and development of technology and related products in the hope of providing the elderly with better life and work environment, as well as supporting medical care. In September 1997, the International Society of Gerontechnology was established in Europe with the purpose to design technology and environment that could help the elderly to live independently, healthily, comfortably and safely, and to able to participate in social activities [17, 18].

3 Methods

The research objectives are divided into three parts, and the research methods include literature review and interviews. First, this study measured the key points of operation design from four aspects of ergonomics (physical and mental status of the elderly, HMI and operation gesture), and reviewed literature on the ergonomic design principle. It then developed the ergonomic engineering principle evaluation form of touch gesture. In the second part, the ergonomic engineering principle evaluation form of usability was developed to evaluate gesture operation status. Based on the scores, individual improvement suggestions were provided. In the third part, the field evaluation was conducted. of the problems identified in the assistant measure design of smartphone for the usage of the elderly were identified, and overall improvement suggestions were proposed. This study also proposed the guiding principle for gesture operations suitable for the elderly. Nielsen and Tullis and Albert pointed out that the usability of evaluation system or user interface is not one-dimensional, but consists of the following five criteria: (1) efficiency, (2) errors, (3) memorability; (4) learnability; (5) satisfaction [14,15,16].

3.1 Collection of Current Products and Sample Selection

This study took the best-selling mobile phone brand products in Taiwan as samples. The smartphones selected by this study were under five brands, include HTC, Samsung, Sony, Apple and ASUS (as shown in Fig. 1). During experiment process, these brand names and enterprise logos were not shown to eliminate the existing impression of participants on some brands. According to literature review, this study summarized the common intuitive gesture designs, including zoom with two fingers, one finger as the fixing and the other finger for rotation, screenshot viewed images by pressing two function keys. The common gesture operation at present is indeed challenging to the elderly.

Fig. 1.
figure 1

Popular mobile phone brands

3.2 Group Positioning and User Observation

This study observed the elderly who use smartphones more often in daily life, and found that the gesture operation is difficult for elderly users. According to previous researches, when using the touch interface of smartphones, the elderly may have problems due to physical degeneration, such as blurred vision, amnesia, insensitivity of touch due to increase of wrinkles. The elderly may have difficulty in recognizing the function pattern on the interface, and find it hard to target the object when operating due to lowered mobility. Moreover, when the elderly were browsing images, they would continuously use two fingers to zoom in/out to adjust the screen due to failure to focus resulted from blurring of vision. They would also touch the screen repeatedly due to insensibility of finger touch, which easily led to error in pressing and mistakenly switching the current viewing pages, thus affecting smoothness of browsing. The operation gesture affected the comfort of smartphone usage. Therefore, the gesture designed for the elderly population should focus on easy comprehension, and simple operation as priority.

3.3 Product Item Analysis (Item Category)

This study took five popular smartphone brands for gesture analysis. Actual measurement, observation and operation were carried out on length, width, thickness, weight, main body shape, color, materials, Logo, operation methods according to appearance (as shown in Table 1).

Table 1. Brand model and operation methods

3.4 Field Interview

This study recruited 30 elderly people aged over 65 with experience in using smart phones. For those who suffer from nearsightedness, farsightedness and presbyopia, corrective therapy or the wearing of an assistant device such as glass should be carried out to ensure the ability in identification and reading. Before the interview, the researcher first introduced the procedures, and explained the current operation gesture of smartphones. The participants were led to experience the zoom-in, zoom-out, rotation, and other operation gestures to view images. During the operation process, the researcher recorded the feedbacks of the participants on their operation gesture experiences. The interview lasted for about 30 min. Each participant was given enough time to think and organize their thoughts. The interviews were expected to identify the operation gestures that satisfy the needs of the elderly users. This study focused on identifying the reason for the usage difficulty of the elderly, and developing the operation method that is most convenient for the elderly (Fig. 2).

Fig. 2.
figure 2

Interactions of hospital volunteers/participants

3.5 Existing Operation Gesture Design Mode in the Market

Based on literature and interview results, this study found that the operation gesture that is difficult for the elderly participants is rotation and zoom-in & zoom out (as shown in Fig. 3, Fig. 4). The reason mainly lies in the insensibility of skin touch of two-finger operation and easy action repetition caused by shaking during operation process. Therefore, it’s difficult for the elderly to use a gesture with over one finger.

Fig. 3.
figure 3

Zoom in and zoom out with two fingers

Fig. 4.
figure 4

The rotation effect with thumb as rotating fixed point, index finger as radius (Traditional Rotation, TR)

3.6 Results of Developing New Design Gesture Mode

This research invited product designer and HMI developers to discuss the innovative design of operation gestures and observed the experiments and studied gesture operation suitable for the elderly. In addition, some past studies showed that due to physical degeneration and natural degeneration, the elderly tend to be slow and inflexible when performing two-finger action. According to actual observation and review of past studies, this research initially developed the prototype of gesture operations suitable for the elderly (as shown in Fig. 5 and Fig. 6).

Fig. 5.
figure 5

Innovative design to achieve zoom-in and zoom-out with one-finger operation (New Design, ND1)

Fig. 6.
figure 6

Innovative design to achieve rotation with one-finger operation (New Design, ND2)

4 Methods

This study evaluated the two operation gestures under innovative design and availability of existing rotating operation gesture (TR). The relationships of various usability evaluation items are as follows: (1) Learning ability: the gesture operation of ND1 is superior to ND2 and TR; to evaluate learning ability, when learning and becoming familiar with the operation, the participants indicated that is it easier to understand of icon meaning of ND1 operation gesture; (2) Efficiency: to evaluate efficiency, this study invited the participants to open one image in the folder, and move the images by innovative zoom-in and zoom-out gesture; as seen from the time recorded, the usage of ND1 operation gesture is more efficient than the usage of ND2 and TR; (3) Memorability: in general, the ease of learning is related to memory to some extent; most of the participants can understand the meaning of ND1 gestures in the interface; during the test, after the participants used smartphones and operation gesture of different brands, they still knew how to use the innovative operation gestures proposed by this study and their meaning; (4) Errors: the error rate is related to efficiency to some extent; this study set one image in the folder, and measured the time spent by the participants to open it, in order to evaluate the efficiency; it found that the longer time taken led to a higher error rate; (5) Overall satisfaction: compared with existing operation gestures, the innovative operation gestures designed by this study received positive feedback (as shown in Table 2)

Table 2. Brand model and operation methods

5 Discussions and Conclusions

In the past studies, there was a preliminary finding that the demand and recognition of the operation of smart devices would change to some extent as the users age. On the contrary, the younger generation had better control over technology products either in familiarity in usage or response to product operation, as compared with the elderly users. Based on the discussion of the human factors and the cognitive, previous studies obtained the effective response time and feedback time data of the elderly users during operation. The results were used to promote the production of smart products with perception, memory, decision making, attention, response execution, and feedback mechanism, in order to meet the needs of lifelong mobility of the elderly users and help them to operate smart devices more conveniently. According to previous literature, the main obstacles faced by the elderly include: deterioration of vision, memory and cognition. The cognition part is the mental factor that caused the elderly users to reject the use of computers. In their opinion, they are too old to use high-tech products or are afraid of breaking the computer during the learning process (Zajicek 2001). Under the social structure tending to aging in the future, for the elderly and those with disability in hands, the intuitive operation and work efficiency should be more valued in product operation. The findings of this study are expected to contribute to the elderly group or those in needs. The topic deserves further attention. In relevant reports about the elderly and technology, the high-tech mobile devices such as mobile phone and tablets are mentioned. The continuously advancing cloud services in recent years has contributed to the fast development in smart mobile devices, and the service providers continue to launch new services to satisfy the usage habit of users. The service providers could reduce learning cost and efficiency for time saved. The entry of more service providers into the market has brought more vigorous development of mobile devices. With understanding of the various factors that influence the touch gestures of the elderly, the service providers could design operation gestures that meet the needs of the elderly users, thus benefiting the elderly population. This will also point a direction for the future development of various touch mobile devices. It is expected that the touch gestures for elderly users can retain the accuracy of the original gestures, while reducing the difficulty in re-learning and memorizing due to human factors of the exiting touch control gestures. The elderly could access the information provided by mobile devices in a more efficient and pleasant way.