A model to conceptualize interactivity - Springer Link

Int J Interact Des Manuf (2009) 3:147–156 DOI 10.1007/s12008-009-0069-5

ORIGINAL PAPER

A model to conceptualize interactivity Tek-Jin Nam · Sunyoung Park · Jouke Verlinden

Received: 11 February 2009 / Accepted: 19 June 2009 / Published online: 31 July 2009 © Springer-Verlag 2009

Abstract This paper presents a model to conceptualize interactivity to help people involved in interaction design. Previous studies on interactivity prototyping focus on tools to implement interactivity concepts. Little is found on models for conceptualizing interactivity. Our objective is to suggest an analytic model to explore the whole user experience by examining the degree of interactivity of a product. This is achieved by interpreting the notion of interactivity as conversation. A conceptualization model, named MCI (model for conceptualizing interactivity), was developed to measure the degree of interactivity. The model can be used to measure and compare the level of user engagement, which in many situations is used as an indication of positive user experience. We illustrate how the model can be used to analyze interactivity in three audio recorder design projects. The proposed model is expected to lead to an interactivity prototyping tool for various product categories including interactive media installations, tangible media, and other intelligent digital products in a ubiquitous computing environment.

T.-J. Nam (B) · S. Park Department of Industrial Design, KAIST, 335 Gwahangno, Yuseong-gu, Daejeon 305-701, Republic of Korea e-mail: [email protected] S. Park e-mail: [email protected] J. Verlinden Faculty of Industrial Design Engineering, Delft University of Technology, Landbergstraat 15, 2628 CE Delft, The Netherlands e-mail: [email protected]

Keywords Degree of interactivity · Conceptualizing interactivity · Prototyping · Interactive product design · Interaction design

1 Introduction As digital products become complex, interaction design emerged as a critical aspect for product success. Preece et al. [27] defined interaction design as designing interactive products to support people in their everyday and working lives. The scope of interaction design covers whole user experience with digital products rather than the communication aspect of inputs and outputs. Interaction designers should address how to use, how to feel, and how to experience products. Researchers from the Human Computer Interaction field stressed the importance of interactivity or interaction for enhancing the quality of user experience with digital products. Buxton [3] insists that a novel interaction can create completely different user experience for the same product. Frens [10] suggested the concept of rich interaction, and showed that different emotional responses can be induced from different interaction styles of a digital camera. Practitioners in the field of interaction design are often trained in traditional design disciplines such as industrial design or visual communication design. One of the big challenges for them is to deal with unfamiliar properties of design subjects of digital products and systems. Traditional products, such as furniture or everyday goods, have largely static and hardware properties. Instead, the properties of recent electronic products become dynamic, temporal, intelligent and interconnected. In order to design and develop products with new properties in the early phase of the design process, many designers still use traditional tools, such as sketches on paper for

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software prototyping or physical mock-ups for hardware prototyping. Traditional prototyping tools and methods are not optimized for the new properties. Hardware of a digital product is often tightly linked with software, but it is difficult to integrate the two in the beginning of the project. In addition, when the integration of the two happens at the last phase of the design process, it becomes too late to alter the design solutions. Often the results become a standard for following products. To address this issue, researchers have developed prototyping tools [9,14,16,23,34]. However, many of the previous studies stressed the implementation of the prototype itself. There is little research done on how to conceptualize interactivity ideas. In the software engineering field, some techniques for conceptualization of system behavior were proposed [4,15]. Svanæs [31] however claims that interaction designers are currently forced by the available tools to express interactivity with concepts derived from the logical mathematical paradigm of computer science. For designers without training as programmers this represents a barrier. Often multimedia authoring tools use a timeline metaphor for conceptualization. However this timeline metaphor is appropriate for prototyping a sequential flow of multimedia, rather than conceptualizing and testing an interactive user experience. Although research interest on interactivity prototyping for designers is increasing, few studied conceptualizing interactivity of information appliances. A new approach is required to conceptualize, to explore, to reflect and to test interactivity, so that whole user experience should be iteratively considered in the early phase of the design process. The aim of this research is to help designers and others involved in interaction design to effectively conceptualize interactivity. The primary objective is to suggest an analytic model to explore the whole user experience and examine the degree of interactivity of digital products as one of the conceptualizing methods. This is achieved by interpreting the notion of interactivity and interactivity prototyping, and by developing a conceptualization model. The model is examined by examining design projects as case study. The model can be used to measure the level of user engagement with digital products including information appliances, which in many situations can be interpreted as an indication of a pleasurable user experience. It is also expected that the proposed model leads to an interactivity prototyping tool for various product categories including interactive media installations, tangible media, and other intelligent digital products in a ubiquitous computing environment. The rest of the paper is organized as follows. Section 2 clarifies the terminology used in this paper and review background theory. In Sect. 3, we present a classification of interactivity prototyping reviewing related works. In Sect. 4, we explain the proposed model to conceptualize interactivity. Section 5 presents design examples as a case study showing

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how the model can be used to conceptualize, explore, measure and examine the interactivity of a digital product, casual sound recorders. A comparison of three designs is presented using this model. In Sect. 6, we discuss findings and related issues. Finally conclusions and future works are presented. 2 Basic theory and terminology 2.1 Interaction, interaction design, interactivity There exist many definitions of interaction and interactivity. It is necessary to clarify the terminology used in this paper. The term interaction design was first proposed by Moggridge and Verplank in the late 1980s [22]. In the computer human interaction field, the meaning of interaction often deals with the communication between human and computer. The meaning of interaction design is more broadly understood in discipline of design. Buchannan [2] explained that interaction design focus on how human beings relate to other human beings through the mediating influence of products. He also mentions that the products are experiences or activities or services, all of which are integrated into a new understanding of what a product is or could be. Rafaeli [28] defined interactivity as an expression of the extent that in a given series of communication exchanges, any third (or later) transmission (or message) is related to the degree to which previous exchanges referred to even earlier transmissions. In the context of communication between a human and an artefact, interactivity refers to the artefact’s interactive behavior as experienced by the human user. This definition considers interactivity can be separated from other design properties, such as physical shape or color. 2.2 Interactivity cycle The notion of interactivity used in this paper is based on the one suggested by Crawford [5]. He defined that interactivity is a cyclic process in which two actors alternatively listen, think, and speak. Main analogy here is a conversation. Based on this analogy, we can assess if interaction flows smoothly. When two persons have a conversation, one starts speaking and the other listens. The other person speaks after thinking about what he or she listens. The speaking becomes an input for listening to the partner. The process of conversation becomes iterative when two actors actively interact. The conversation sometimes evolves or terminates depending on the topic. The topics of conversation can be for fun or question and answer. In conversation, thinking of an actor becomes important. For an intelligent product to be an interactive actor, the whole cycle of listening, thinking and speaking should be supported (Fig. 1). We assume that a user becomes engaged, excited or interested by a fluent flow of conversation. The quality of

A model to conceptualize interactivity

149 Table 1 Grice’s Maxims of communication [11]

Fig. 1 Interaction cycle: listening, thinking and speaking

interactivity depends on the degree of interactivity cycle: listening, thinking, and speaking. The degree of listening is decided by the number of understandable vocabularies. In a product, this can be compared to the number of input channels, such as the number or sensitivities of sensors that can accept external information. Examples include cameras having the capability of getting visual information, or touch-sensors having the capability of recognizing tactile input. The degree of thinking is determined by how thoughtful a product is. The product decides what to respond to a user after understanding inputs. This intellectual capability includes a power of understanding user and user’s situation or context. The degree of thinking would be at a low level when the response to listening is almost unconscious regarding users or their situations. If a product is context-aware or can extract the intention of a user, the degree of thinking would be high. The degree of speaking represents how many words or sentences a product can generate. In a product, output devices such as monitor, speaker, and actuators creating physical movement take the role of speaking. Eloquent speaking subsequently triggers next conversation to a user. The degree of interactivity depends on the iterative process of listening, thinking, and speaking. To measure its degree, we can scrutinize whether user and product did successfully execute good listening, thinking, and speaking. Since these three factors act interdependently, if one factor fails the whole interactive conversation cannot be continued. Our assumption is that a systematic conceptualization of interactivity can be achieved by analyzing the degree of each process and by considering how the total flow of interactivity evolves. This paradigm also allows the application of a plethora of dialog and linguistic tools to the field of tangible computing and interaction with intelligent products. Most prominently, the Maxims of Conversation represent guidelines for designing dialog acts, see Table 1. In his words, these served to ensure to “Make your conversational contribution such as is required, at the stage at which it occurs, by the accepted purpose or direction of the talk exchange in which you are engaged” [11]. In similar terms, we can devise Maxims of Interactivity to introduce rules of thumb to designers. This will be revisited in Sect. 6.

Quantity

Be exactly as informative as is required : Make your contribution as informative as required (do not say too much or too little) Make the strongest statement you can

Quality

Try to make your contribution one that is true: Do not say what you believe to be false. Do not say that for which you lack adequate evidence.

Relevance

Be relevant: Stay on topic.

Manner

Be perspicuous Avoid obscurity of expression. Avoid ambiguity. Be brief (avoid unnecessary prolixity). Be orderly.

The notion of interactivity used here has a different standpoint from other concepts of interaction. For example, the concept of direct manipulation [30] and tangible user interfaces [32] combine the view and the controller of the modelview-controller (MVC) paradigm [19]. View, Model and Controller cannot be mapped to listening, thinking and speaking as the MVC paradigm focuses on means of interaction, i.e physical or tangible media. Whereas our interpretation of interactivity is broader as it is considered to be one constituent of a digital product. That means interactivity used here addresses the whole user experience in which interface media become the part of a product or a system of products. 3 Classification of interactivity prototyping In this section, we present a classification of interactivity prototyping. A fidelity criterion is frequently used to classify prototypes [27]. Low fidelity prototypes are simple, cheap and quick to produce. They often used for exploration of alternative designs and ideas. High fidelity prototypes are for accurate simulation of final design, in the form of physical working model or software systems. It takes more resources or a longer time to build. In addition to this criterion, we present three more criteria to classify interactivity prototyping: purpose of prototyping, the level of conceptualization and main parts covered in the interactivity cycle. 3.1 Purpose of prototyping There can be three purposes of interactivity prototyping in the design process. The first is to understand users. Sometimes designers use prototyping methods in order to understand users’ cognitive model or context. For example, participatory diagramming is a method that users and designers think together about conceptual structures or flowcharts for a new interface, based on activity flow diagrams created on the spot [13]. By investigating the user’s mental model or their natural

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flow of interaction manner, designers try to apply user’s interaction flow to conceptualizing interactivity. The second is to identify user’s needs or desire for interactivity. In order to find out user needs and desires, users are challenged to express their thought of interactivity [29]. Cultural probe [12] or co-creation tools [33] are used for this purpose in typical new product design projects. The final one is to explore new concepts of interactivity. Some prototyping methods can be used for exploring ideas of interactivity. For example, interaction relabeling aims to explore new interaction techniques using existing products like revolver gun [8]. In a participatory workshop, users and designers apply existing products’ mechanism by exploring physical attributes of interesting materials such as elastic string [17,18]. 3.2 The level of conceptualization Interaction prototyping can also be classified according to the level of conceptualization. Some prototyping tools support concept formulation [20] while others support implementation of the concept. For example, many of existing prototyping tools including DART [23], phidgets [14], caldar toolkit [1], k-sketch [7] and d.tools [16] were developed to support building interactive prototypes. Whereas conceptual diagram techniques such as statecharts [15] or state diagrams in UML [4] are used to conceptualize the process flow or user interface. 3.3 Main parts covered in the interactivity cycle The final criterion to classify interactivity prototyping is whether the main focus of prototyping corresponds with the interactivity cycle of speaking, thinking, and listening. Some prototyping methods are mainly implemented for examining input–output communication [10]. They tend to cover on speaking and listening parts. Other prototyping tools are only focused on the thinking part [21,24]. They are used to conceptualizing dynamic flow of contents or its structure. However, in existing literature the full cycle of interactivity prototyping is not covered. Through developing and analyzing the classification of existing interactivity prototyping tools and methods, we figured out that there is a lack of method to conceptualize interactivity from a design perspective. 4 Proposed model for conceptualizing interactivity (MCI) Our model, named as MCI, assumes that interactivity can be considered independently from other properties of a product. It also assumes that the frequency of listening–thinking– speaking cycles can act as a measure of the degree of

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T.-J. Nam et al. Table 2 Analogy of terms used describing the degree of interactivity

interactivity. The higher the degree of interactivity is, the more user engagement is achieved. The model also considers the degree of each interactivity cycle by decomposing it into listening, thinking and speaking. In Sect. 2, we explained the metaphor of conversation to describe interactivity. Positive conversation takes place between more than one actor in a certain context. The context corresponds to a situation in a conversation. Topics of conversation can be compared to functions of the product, or tasks that a user is trying to accomplish. Listening of a product is input or control from a user. Thinking corresponds to processing or intelligence of the product. Speaking is the way to present the result. Table 2 shows this analogy. The degree of interactivity is related to how interesting the topic of conversation is for the involved actors. The topic of conversation conveys the product’s function or activity. For example, for an audio player, the functions (or task from user’s point of view) can be playing or recording music. While positive conversation between a product and a user evolves, the degree of interactivity also increases gradually. Main concept of our model is that the degree of interactivity is represented by the number of the positive cycles of listening, thinking and speaking take place in a given situation. The model measures the number of situations that the product can support, the frequency of listening–thinking–speaking cycles in each situation, and the quality of each phase on interactivity cycle, ie. listening, thinking, and speaking. The following is an equation to describe the degree of interactivity. Degree of interactivity =

cy s

{fL(n, m) · fT(n, m)

n=1 m=1

· fS(n, m)} cy = The number of cycles in which the process ‘listening–thinking–speaking’ executed until one topic terminates fL() = Formula determining the degree of listening fT() = Formula determining the degree of thinking fS() = Formula determining the degree of speaking s = The number of situations.


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For example, a smart mp3 player suggests a list of songs of users preference depending on who is the user and when the usage situation is. The list is also decided by the context. The player may suggest a special list in the morning, if the user listens to certain genre of music in the morning. This feature increases the degree of thinking compared to a normal mp3 player. Fig. 2 Visual representation of the model for conceptualizing interactivity (MCI) in one situation

When the same topic (function or task for user product interaction) is used in a different situation, this can be another cycle of interactivity as far as the content of conversation is different. Different users or contexts can create new situations. For example, if a product differentiates its interface for either young users or aged users, the degree of interactivity become higher because the degree of interactivity is multiplied by the number of situations, in this case encompassing two different user groups. The degree of interactivity also increases by the number of cycles. Figure 2 shows the degree of interactivity described in a given situation. The quality of each cycle is decided by the degree of each phase of interactivity, represented by fL(), fT(), and fS(). 4.1 Degree of listening: fL() Parameters of ‘fL()’ include characteristics of input, and the underlying input method, although some of these parameters are difficult to quantify. We can estimate the degree of fL() by considering: How accurately or sensitively does the product accept user’s speaking? How novel does it feel by users? For example, let us suppose that there is a volume controller of a product that accepts the tree input types; low, medium, and high. The other type of the volume controller accepts a continuous analog range from low to high. In terms of the quality of listening, the latter is higher than the first because of the sensitivity of listening. A multi-touch screen has higher novelty than an existing touch screen, it increases the degree of listening as well.

4.3 Degree of speaking: fS() fS() represents the ability to create understandable representations and the quality of expressions. fS() can be estimated by measuring: How well is the output understood and recognized by the user? How much does the speaking yield another engagement from user? 5 Case study: application of the MCI model in analyzing interactivity of casual sound recorders We applied the proposed model to examine the interactivity of a casual sound recording device. The purpose of the case study was to see whether the method can be used to conceptualize and examine the interactivity. We also compared the interactivity with those of other products using the model. Two tasks of recording and playing back were compared in terms of each part of interactivity cycle. It was also investigated whether the model can be used to measure and compare the degree of interactivity in a structured way. 5.1 Talkative cushion Talkative cushion [25] is an interactive sound recorder. The hardware has a form of a talking bubble. The cushion may be used with a public chair or sofa (Fig. 3). A user can

4.2 Degree of thinking: fT() fT() represents the ability to be aware of situation, context or intention of a user. The parameters of fT() may include: How intelligent is this product? Is it smart enough to understand user’s intention? How well the product is aware of user or user’s context?

Fig. 3 Talkative cushion [25]

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5.1.2 Interactivity of playback

Listening : The user grasps the tail of the sound-bubble cushion. Thinking : The device records sound. Speaking : The device shows the state of recording. Listening : The user release the tail. Thinking : The device finishes recording. Speaking : The device shows the state of the end of recording.

Fig. 4 The degree of interactivity of Talkative cushion for the recording task

record sound or speech for indirect communication with other users using the cushion. When playing back, it provides playful user experience through interactively transformed sound. The sound bubble shape offers a more friendly and enjoyable way of recording. For recording, the user holds the tail part of the sound bubble. For playing back, the user pushes the cushion. The pressure generates different tone and speed of sound. The unusual way of recording and playing back provides rich user experience with the device. The interactivity of Talkative cushion can be decomposed as below for two main tasks 5.1.1 Interactivity of recording In the recording task, listening takes place by the event that the user holds the tail of the sound bubble cushion. Then the thinking part records the sound within the device. The cushion shows the state of recording, as a speaking part. If the user releases the tail, it stops recording. The device shows the end of recording. Therefore, this recording task has two cycles as shown in Fig. 4.

In the playback task, listening takes place by users pushing the cushion. The device loads the recorded sound to the memory. It plays back the sound. The user pushes the device in different pressure. It changes the tone and speed of the playback sound. The sound is played back from the internal speaker. This cycle repeats until the user stops pressing the cushion (Fig. 5). In designing interactivity, the model was used to consider different alternatives of listening, thinking and speaking. It was possible to examine full cycle of interactivity in different tasks and situations. The model also helped for designers to consider ways to trigger a new cycle. 5.1.3 Interactivity of playback In the playback task, listening takes place by users pushing the cushion. The device loads the recorded sound to the memory. It plays back the sound. The user pushes the device in different pressure. It changes the tone and speed of the playback sound. The sound is played back from the internal speaker. This cycle repeats until the user stops pressing the cushion (Fig. 5). In designing interactivity, the model was used to consider different alternatives of listening, thinking and speaking. It was possible to examine full cycle of interactivity in different tasks and situations. The model also helped for designers to consider ways to trigger a new cycle. 5.2 The SpeakCup sound recorder SpeakCup was designed to explore mapping functional status to physical appearance [6]. The main concept is that the mode

Fig. 5 The degree of interactivity of Talkative cushion for the playback task

Listening : User, B pushes the cushion. Thinking : The product prepares recently recorded sound. Speaking : The product starts to play back. Listening : User, B pushes the cushion again, stronger. Thinking : The product recognizes the pushing power of user B. Speaking : The product plays back sound at speed rate which corresponds to the power of pushing. (Repeating until user B releases the product down.)

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Listening : The user makes the device convex. Thinking : The device plays back the recently recorded sound. Speaking : The device shows the state of playback through the form. Listening : The user makes the device flat. Thinking : The device finishes recording. Speaking : The device shows the state of the end of playback through the form.

Fig. 8 The degree of interactivity of SpeakCup sound recorder for the playback task

Fig. 6 SpeakCup sound recorder [6]

of the device is an indicated through form (Fig. 6). The proposed design uses a flexible bowl shape that can be flattened as well as bent in either direction. On one face is a pattern of holes, suggesting audio input or output. When flat, the device is off. When the user wishes to record, he or she flexes the form such that the holes sit at the bottom of a dish. This cupshaped form suggests collection, or capture from an external source. To play back, the user flexes the shape to the other direction. The holes are now atop a dome shape, suggesting projection or broadcast. The device becomes a point source. Note that when flexing the device, the motion of the thumbs with respect to the audio holes indicates the user’s desire. Pushing against the holes (as if forcing something into them) creates the record mode form. Pushing them from behind (as if forcing something out) creates the playback shape. Interactivity of the device for recording and playback tasks can be decomposed as in Figs. 7 and 8.

Fig. 9 Candle recorder [24]

Hence, the recorder is designed as a candle stand (Fig. 9). The candlelight is sensed and tracked by an inexpensive infrared light sensor, with an LED lit up to indicate that a recording is taking place. When the user extinguishes the flame, the recording stops. To play back the recording, the user simply flips the candle stand over and the device becomes a small speaker. To start playback, the user twists the device, twisting it again will fast forward to the next recording and twisting it in the opposite direction will stop the play back. Interactivity of the device for recording and playback tasks can be represented by our model as in Figs. 10 and 11.

5.3 The candle recorder

5.4 Comparison of interactivity of three recorders

The Candle Recorder is a sound recorder designed to use in the context of a party, dinner, or other similar occasion [26]. Lighting the candle in such a context forms a natural trigger indicating a beginning of an event to start recording.

5.4.1 Interactivity of recording

Listening : The user makes the device concave. Thinking : The device is recording sound. Speaking : The device shows the state of recording through the form. Listening : The user makes it flat. Thinking : The device finishes recording. Speaking : The device shows the state of the end of recording through the form.

Fig. 7 The degree of interactivity of SpeakCup sound recorder for the recording task

The analysis of interactivity of three recorders using the MCI model shows similar degree of interactivity with respect to

Listening : The user lights the candle. Thinking : The device records the sound. Speaking : The device shows the state of recording. Listening : The user extinguishes the light of the candle. Thinking : The device finishes recording. Speaking : The device shows the state of the end of recording.

Fig. 10 The degree of interactivity of the candle recorder on the ‘recording’ topic

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bubble cushion. For the SpeakCup Recorder it is to transform shape of the product, while listening for candle recorder is to light on and extinguish the candle. Unlike the other two recorders, the Candle Recorder is targeted to specific situations, such as a party, a dinner, or other similar occasions. However, as it does not make any difference in terms of interactivity cycle regardless of different context of use, the total degree of interactivity remain same. Listening : The user flips the candle stand over. Thinking : The device prepares recently recorded sound. Speaking : The device plays the sound and shows the state. Listening : The user twists a surface of the bottom of candle. Thinking : The device retrieves the recently recorded sound. Speaking : The device plays back the recently recorded sound and shows the state. Listening : The user twists the surface again.

Fig. 11 The degree of interactivity of the candle recorder on the ‘playback’ topic

Table 3 Comparison of the degree of interactivity for the recording task fL( )

fT( )

fS( )

L-T-S cycles

Situation

Talkative Cushion

Grasping and Releasing the tail of the cushion

Recording sound

Terminating recording

2 cycles

UserIndependent ContextIndependent

SpeakCup Recorder

Making a recorder concave and planer

Recording sound


2 cycles


Candle Recorder

Lighting and extinguishing the candle

Recording sound


2 cycles


the task of recording. All three devices have similar degree of fL(), fT() and fS(), as shown in Table 3. The number of the cycles is two. The input styles are all novel. Listening of Talkative cushion is behavior to grasp the tail of the sound

5.4.2 Interactivity of playback All three recorders have a different degree of interactivity with respect to the task of playback. The number of interactivity cycles differs due to different input and output methods of the devices. The Candle Recorder does not recognize user’s identity. It only recognizes the two directions (clockwise and counter clockwise) and times of twisting for listening. SpeakCup Recorder accepts three states as input. It always prepares recently recorded sound. It has one type of playback. Talkative cushion accepts continuous pressure input. The analog input yields many cycles by just applying different pressure to the cushion. The tone and speed of playback is changed and creates more loops. Therefore, it can be said that the degree of the Talkative cushion recorder is the highest among the three followed by the candle recorder and the SpeakCup recorder. Table 4 shows the comparison of interactivity for the playback task.

6 Discussion Designers tended to focus on specific cycles of interactivity or situations. This may be improved with the MCI model. In the design process of the Talkative cushion, the MCI model was helpful in analyzing interactivity. Other design projects in a master level studio based course of interactive product design, students successfully applied MCI to consider all

Table 4 Comparison of the degree of interactivity for the playback task fL( )

fT( )

fS( )

L-T-S cycle

Situation

Talkative Cushion

Pushing and lay down the cushion

Preparing the tone and speed of playback sound depending on the pressure from the user.

Playback at rate of speed corresponding to the pressure.

The number of cycle can be infinite depending on user’s decision

UserDependent

ContextIndependent

SpeakCup Recorder

Making a recorder convex and planer

Always preparing recently recorded sound

Always playback recently recorded sound

2 cycles

UserIndependent

ContextIndependent

Candle Recorder

Flipping the candle and twisting the candle

Preparing sound by recognizing the frequency of twisting and the direction of the rotation.

Playback recorded sounds in a sequential order.

As many as the number of previously recorded sound

UserIndependent

ContextIndependent

123


levels of interactivity cycle in different tasks and in different situations. Although the impact of MCI model in the design process should be structurally studied, our preliminary educational experience suggested that alternatives were effectively explored by designers while considering ways to increase the number of interactivity cycles. The application and the comparison of interactivity described above are illustrative. We found that the model was useful when comparing different interactive devices of similar kind. However, it is still difficult to quantify the degree of interactivity in detail. Some parameters in the model, such as novelty of input or output types, are difficult to estimate. Nevertheless, the systematic exploration can be possible when used with diagrammatical representation of the model. Furthermore, a translation of Grice’s Maxims as proposed in Sect. 2.2 will generate guidelines for designers to tune and optimize the level of interactivity. Expressions of quantity, quality, relevance and manner can be formulated in generic objectives, or tuned to more detail based on the intentions of the product. Our model is mainly targeted to interactive digital products with both hardware and software properties. In many cases, interactive products have many usage situations and tasks. Existing methods used in software engineering are too detailed or complex while considering specific tasks for designers. Sometimes it focuses on thinking part of interactivity cycle. Little alternatives can be explored for listening and speaking parts. Our model can explore all the interactivity cycles by considering situations and tasks expected in whole user experience. The method can also be employed during the design of other products and systems including software, websites and interactive media. Meantime, our model is more appropriate to conceptualize the quality of interaction rather than other criteria of measuring usability such as efficiency or effectiveness when people use an interactive product. Sometimes usability enhancement means reducing the time to complete specific task or shortening the route of interaction. This is true when there is a specific task to complete with a product. Instead, our model is targeted to creating pleasurable user experience with new interactive products or systems. It is assumed that the increased interactivity cycles initiate more active user engagement. It is believed that in many situations this is an indication of more pleasurable user experience. The notion of a dialog is very much in line with a sequence diagram in UML [4]. In practical terms, standard UML diagramming tools may be used to specify the interactivity. However, there are some theoretical problems with such specifications. Most notably the exhaustiveness is limited in comparison with State Transition Diagram or flowchart. For complex product interactions with many branches, designers will have to define all possible paths. Furthermore, exception handling is difficult to express (e.g. receiving a phone

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call while a user is making pictures with a multifunctional mobile phone). The MCI model can be effectively used when there is an optimized design tool. For example, a software application can be developed to help designers check alternative inputs and outputs. It may help evaluate the degree of interactivity by the number of cycles and the quality of cycles. If the model were applied to existing products, it would be possible to analyze the interactivity, and to identify problems of existing interactivity. It can also be extended to a tool to explore new concepts for interaction in co-creation sessions with users or other stakeholders. The MCI model covers all parts of interactivity. Listening and speaking sometimes require the exploration of physical and tangible media. An interactive design tool to support the tangible manipulation or exploration of different alternative of listening and speaking can be a useful for conceptualizing interactivity.

7 Conclusion This paper presented an analytic model to conceptualize interactivity. Based on a review of interactivity prototyping methods, and re-interpretation of the definition of interactivity, we suggest MCI. This model is aims to systematically conceptualize interactivity considering the degrees of listening, thinking and speaking part of interactivity cycle. Without the model, designers tend to narrowly focus on specific parts of interactivity or particular cycle of task. The analytical approach enables designers to go though the critical investigation of the whole user experience of the product. It also helps to create more concrete user scenarios. Designers of computer-based media are currently to express interactivity by concepts derived from the logical mathematical paradigm of computer science. For designers without training as programmers this constitutes a barrier. The MCI and its diagrammatic representation support kinaesthetic thinking [31]. Interactivity can be initiated by material or mechanical mechanism. In order to expand the user experience, it would be considered together with the flow of conversation. This paper presents a new perspective on conceptualizing interactivity. It can also be used as a tool to measure or benchmark the efficiency or quality of interactivity. As future work, more design projects need to be undertaken to examine the applicability of the model to different type of products. The parameters can be further refined and optimized. Based on the model, a new interactivity prototyping tool can be developed for different purposes, i.e. to understand users’ mental model of interaction, to identify the problems while using a product, or to explore new concepts of interaction. Developing a tool for co-creation of interactivity

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with users or other stakeholders in a user context is also one of the future directions. Acknowledgments This work was supported by the Korea Research Foundation Grant funded by the Korean Government (MOEHRD), Basic Research Promotion Fund (KRF-2007-327-G00040).

References 1. Avrahami, D., Hudson, S.E.: Forming interactivity: a tool for rapid prototyping of physical interactive products. In: Proceedings of DIS’02 (2002) 2. Bucannen, R.: Design research and the new learning. Des. Issues 17(4), 3–23 (2001) 3. Buxton, B.: Sketching User Experience: Getting the Design Right and the Right Design. Morgan Kaufmann, Menlo Park (2007) 4. Booch, G., Rumbaugh, J., Jacobson, I.: The Unified Modeling Language user guide. Addison Wesley Longman, Redwood City (1999) 5. Crawford, C.: The Art of Interactive Design. No Starch Press, San Francisco (2002) 6. Chang, A., Gouldstone, J., Zigelbaum, J., Ishii, H.: Simplicity in interaction design. In: Proceedings of TEI’07 (2007) 7. Davis, R., Colwell, B., Landay, J.: K-Sketch: A “Kinetic” sketch pad for novice animators. In: Proceedings of CHI’08 (2008) 8. Djajadiningrat, J.P., Gaver, W., Fres, J.: Interaction relabelling and extreme characters: methods for exploring aesthetic interactions. In: Proceedings of DIS’00, pp. 66–71 (2000) 9. Dore, R., Pailhes, J., Fischer, X., Nadeau, J.: Identification of sensory variables towards the integration of user requirements into preliminary design. Int. J. Ind. Ergonomics 7(1), 1–11 (2007) 10. Frens, J.: Designing for rich interaction: integrating form, interaction, and function. In: Proceedings of the 3RD Symposium of Design Research: Drawing New Territories, Swiss Design Network (2006) 11. Grice, H.P.: Logic and conversation. In: Cole, P., Morgan, J. (eds.) Syntax and Semantics: Speech Act, vol. 3, pp. 43–58. Academic Press, New York (1975) 12. Gaver, W., Dunne, A., Pacenti, E.: Design: cultural probes. Interactions 6(1), 21–29 (1999) 13. Greenbaum, J., Kyng, M.: Design at Work: Cooperative Design of Computer Systems. Lawrence Erlbaum Associates, Hillsdale (1991) 14. Greenberg, S., Fitchett, C., Phidgets: Easy development of physical interfaces through physical widgets. In: Proceedings of UIST’01 (2001) 15. Harel, D.: Statecharts: a visual formalism for complex systems. In: Harel, D. (ed.) The Science of Computer Programming, pp. 231–274 (1987) 16. Hartmann, B., Abdulla, L., Mittal, M., Klemmer, S.: Authoring sensor-based interactions by demonstration with direct manipulation and pattern recognition. In: Proceedings of CHI’07 (2007) 17. Jensen, M.V.: A physical approach to tangible interaction design. In: Proceedings of the 1st International Conference on Tangible and Embedded Interaction (2007)

123

T.-J. Nam et al. 18. Jensen, V.J., Buur, J., Djajadiningrat, T.: Designing the user actions in tangible interaction. In: Proceedings of the 4th Decennial Conference on Critical Computing: between Sense and Sensibility. ACM Press, New York (2005) 19. Krasner, G.E., Pope, S.T.: A cookbook for using the modelview controller user interface paradigm in Smalltalk-80. J. ObjectOriented Program. 1(3), 26–49 (1988) 20. Landay, J.A., Myers, B.A.: DENIM: interactive sketching for the early stages of user interface design. In: Proceedings of Human Factors in Computing Systems, pp. 43–50 (1995) 21. Microsoft Office Visio 2007, http://office.microsoft.com/en-gb/ visio. Accessed June 2008 22. Moggridge, B.: Designing Interactions. MIT Press, Cambridge (2007) 23. MacIntyre, B., Gandy, M., Dow, S., Bolter, J.: DART: a toolkit for rapid design exploration of augmented reality experiences. In: Proceedings of ACM Symposium User Interface Software and Technology, UIST’04, pp. 197–206 (2004) 24. Nam, T.-J.: Sketch-based rapid prototyping platform for hardware– software integrated interactive products. In: Proceedings of CHI’05 Extended Abstracts on Human Factors in Computing Systems, pp. 1689–1692. ACM Press, New York (2005) 25. Kim, C., Nam, T.-J.: Talkative cushion: a phatic audio device to support family communication. In: Proceedings of CHI’09 extended abstracts on human factors in computing systems, pp 2631–2634. ACM Press, New York (2009) 26. Poupyrev, I., Oba, H., Ikeda, T., Iwabuchi, E.: Designing embodied interfaces for casual sound recording devices. In: Proceedings of CHI’08 (2008) 27. Preece, J., Rogers, Y., Sharp, H.: Interaction Design: Beyond Human–Computer Interaction. Wiley, New York (2002) 28. Rafaeli, S.: Interactivity: from new media to communication. In: Hawkins, R.P., Wiemann, J.M., Pingree, S. (eds.) Sage Annual Review of Communication Research: Advancing Communication Science: Merging Mass and Interpersonal Processes, vol. 16, pp. 110–134. Sage, Beverly Hills (1998) 29. Sanders, E.B.N.: Generative tools for codesigning. In: Scrivener, S., Ball, L., Woodcock, A (eds.) Collaborative Design. Springer, London (2000) 30. Schneidermain, B.: Direct manipulation: a step beyond programming languages. LEEE Comput. 16(8), 57–69 (1988) 31. Svanæs, D.: Understanding Interactivity; Steps to a Phenomenology of Human–Computer Interaction. Ph.D. dissertation, Department of Computer and Information Science, Norwegian University of Science and Technology, Trondheim, Norway (1999) 32. Ullmer, H., Ishii, H.: Emerging frameworks for tangible user interfaces. IBM Syst. J. 39(3–4), 915–931 (2000) 33. Visser, F.S., Visser, V.: Re-using Users: Co-create and Co-evaluate. Springer, London (2005) 34. Yim, J., Nam, T.: Developing tangible interaction and augmented reality in director. In: Proceedings of CHI’04 Extended Abstracts on Human Factors in Computing Systems (2004)