Jaedong Lee
email: jdlee@korea.ac.kr

Youngsun Kim

Gerard J Kim
email: gjkim@korea.ac.kr

Applying "Out of Body" Vibrotactile Illusion to Two-Finger Interaction for Perception of Object Dynamics

Keywords: Out-of-body illusion, Illusory tactile sensation, Pinch interaction, Vibrotactile interaction

Vibrotactile feedback is an effective and economical approach for enriching interactive feedback. However, its effects are mostly limited to providing supplementary alarms or conveying the sense of simple object presence or contact. We propose to apply the "out of body" tactile illusion for selecting and manipulating a virtual moving object while also being able to feel its dynamics using two fingers. We assessed the user experience (focusing on the perception of the dynamics of the selected object) of the proposed method by comparing it to the conventional contact-based method. Our results indicate that users were able to perceive the dynamic feedback, and preferred it over the conventional method.

Introduction

Vibrotactile feedback is an effective and economical alternative to mechanically complex haptic devices. Despite its simplicity, it produces good results, especially when coordinated in a multimodal fashion with other associated feedback [START_REF] Linjama | Novel, minimalist haptic gesture interaction for mobile devices[END_REF]. Still the effects are to mostly provide the sense of physical existence only. Therefore, it would be desirable for vibrotactile feedback to have the ability to express other aspects such as more dynamic interactions with objects (e.g., feeling a pulsating heart or holding on to a live animal). To achieve such a goal, we propose to apply an "out of body" tactile illusion. Funneling is one of the most notable illusory feedback techniques associated with vibrotactility [START_REF] Alles | Information transmission by phantom sensations. Man-Machine Systems[END_REF]. Funneling can generate illusory tactile sensations by presenting two or more simultaneous tactile stimuli directly to two parts of the body.

It is also possible to elicit a "moving" directional sensation by rendering successive funneling stimulations, which is also known as the "apparent movement" [START_REF] Israr | Tactile brush: drawing on skin with a tactile grid display[END_REF][START_REF] Seo | Initial study for creating linearly moving vibrotactile sensation on mobile device[END_REF]. Miyazaki et al. [START_REF] Miyazaki | The "cutaneous rabbit" hopping out of the body[END_REF] discovered that a tactile illusion could be extended to "body connecting" objects and that it could create illusory sensations that from "out of the body," e.g. as if coming from an object that is external to the user's body.

Based on these illusion phenomena, we propose a two finger interaction method where two fingers "pinch" an object, and two vibration motors attached to the two tips of the fingers convey tactile touch/contact and directional object dynamics (see Figure 1). The proposed method is comparatively assessed for its user experience (focusing on the perception of the dynamics of the object) through a user experiment.

Related Work

The mechanism most commonly used to generate hand-held tactile/haptic feedback has been employing small vibrating motors. These have been mostly used with mobile devices or hand-held game controllers to provide supplementary feedback for various interaction events (e.g., alarm, touch/key input, and virtual collision). Researchers have searched for ways to simulate other types of information by controlling the vibrating signal (e.g., texture simulation) [START_REF] Okamura | Vibration feedback models for virtual environments[END_REF] and by combining it with other modalities [START_REF] Hoggan | Mobile multi-actuator tactile displays[END_REF]. Nevertheless, vibrating motors are still inherently limited in terms of their ability to convey true haptic force, i.e., rigid contact as well as directional or inertial effects. Piezo-electric materials are another popular technology that is used for tactile feedback for mobile and hand-held devices [START_REF] Poupyrev | Ambient touch: designing tactile interfaces for handheld devices[END_REF][START_REF] Chubb | Shiverpad: A glass haptic surface that produces shear force on a bare finger[END_REF]. However, while this method is able to recreate static surface textures, e.g., protrusions and bumps, the devices lack features to provide more dynamic feedback.

A number of researchers have applied tactile illusion techniques to human interfaces [START_REF] Israr | Tactile brush: drawing on skin with a tactile grid display[END_REF][START_REF] Seo | Initial study for creating linearly moving vibrotactile sensation on mobile device[END_REF][START_REF] Hoggan | Mobile multi-actuator tactile displays[END_REF][START_REF] Mizukami | Tactile information transmission by apparent movement phenomenon using shape-memory alloy device[END_REF][START_REF] Ooka | Virtual object manipulation system with substitutive display of tangential force and slip by control of vibrotactile phantom sensation[END_REF] e.g. to minimize the number of tactile actuators (instead of using a comparable tactile array) [START_REF] Hoggan | Mobile multi-actuator tactile displays[END_REF] or to design vibrotactile feedback method that do not require direct contact to the fingers/hands. However, most of the prior tactile interactions have focused only on the providing feedback to indicate an existence of an object, the perception of texture patterns, and the outer shape of the object rather than its dynamics. In addition, illusion techniques have been usually applied to a continuous skin area rather than external to the body. Thus, applying the out of body tactile illusion seems one promising way to enrich the feedback while improving the general usability.

3

Experiment: Perception of Dynamics by Out of Body Tactile Illusion in Two-finger Interaction

Experimental Set-up and Procedure

We demonstrate an application of "out of body" tactile illusion for two-finger object selection and manipulation and experimentally assesses whether the proposed method can bring about an improved user experience, when compared to conventional methods, by providing tangibility and sensation of the object and its interaction dynamics. Fourteen paid subjects, 10 men and 4 women with a mean age of 25, participated in the experiment. An experiment with one-factor (3 feedback methods) within-subject with repeated measures was conducted. The task was to pick and hold a moving object (an animated fly) (Figure 1). Both fingers were tracked using the Leap Motion sensor, and two conventional methods with no vibrotactile feedback (NF) and contact-only feedback (CF, nominal vibration given only for indicating contact with fingers) were compared to the proposed method (TI) where tactile illusion rendering was applied to the fingertips. No quantitative performance was measured, and only a questionnaire of the user's experience was filled out (for the questionnaire categories, see Figure 2).

Results

Figure 2 shows the average responses to the seven UX survey questions and the differences among the three feedback methods. In most categories (except for the "Fatigue" category), it is quite clear that the proposed method (TI) exhibited a much more positive user experience. Obviously, the NF condition scored the least in all UX categories. In fact, the Kruskal-Wallis test (non-parametric analysis) revealed that there existed statistically significant differences in all categories except for Q6 (Fatigue). A Tukey test using Ranks post-hoc analysis showed that the proposed method had statistically significant effects over the NF and CF. Note that to convey the feelings of object dynamics, providing only contact feedback (CF) at the respective fingertips would not be sufficient because the object may be moving at the mid-location without direct contact with the fingertips. The subjects also showed an overwhelming preference for the proposed method (TI) (out of 14 subjects, 13 for task). In summary, the experiment demonstrated that the interaction experience can be significantly improved through the proposed tactile illusion based rendering of the interaction object dynamics.

Discussion and Conclusion

In this paper, we have presented the possibility of applying an "out of body" tactile illusion to a two-finger object interaction in order to improve the user experience without causing significant fatigue. We strongly argue that the proposed tactile rendering of the object dynamics (and not just a multimodal fusion) was the contributing factor to the improvement in the interaction experience. The proposed method can be applied to many other interactive tasks, such as in tangible manipulation of augmented objects, interacting with holographic/stereoscopic virtual objects, surface computing, etc. Our future work will continue to develop and apply other illusion based techniques (including saltation) in a similar manner. One disadvantage of the proposed method is in its wearability. We are investigating whether the vibrators can be positioned and worn like a ring with similar effects.

Fig. 1 .

 1 Fig. 1. The proposed vibrotactile illusion based interaction method for holding a moving object and feeling for its dynamics (left), and its experimental implementation (right).

Fig. 2 .

 2 Fig. 2. Responses to the UX questionnaire for and differences among the three feedback methods (the error bars indicate the standard error of the mean).

Acknowledgement

This research was supported by Basic Science Research Program (No. 2011-0030079) and International Research & Development Program (Grant number: 2014K1A3A1A17073365) through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning


Ryo Ishii
email: ishii.ryo@lab.ntt.co.jp

Shiro Ozawa
email: ozawa.shiro@lab.ntt.co.jp

Akira Kojima
email: kojima.akira@lab.ntt.co.jp

Kazuhiro Otsuka
email: otsuka.kazuhiro@lab.ntt.co.jp

Yuki Hayashi
email: hayashi@kis.osakafu-u.ac.jp

Yukiko I Nakano
email: y.nakano@st.seikei.ac.jp

Design and Evaluation of Mirror Interface MIOSS to Overlay Remote 3D Spaces

Keywords: Mirror interface, motion parallax, 3D modeling, overlaid space

The MIOSS mirror interface can overlay two remote spaces, enabling users to feel as if they are in the same room and thereby to share 3D objects in the spaces. MIOSS imparts motion parallax through a mirror that adjusts to the viewpoint of the user, in addition to providing geometrical consistency in the occlusion, size, and positional relationships in the two remote spaces. Experimental evaluations of an implemented MIOSS system show that users can recognize the exact positions of shared objects in the partner's space via the mirror video.

Introduction

One of the big challenges in creating media spaces is how to achieve the sharing of remote spaces containing people and objects. If this can be achieved, we will be able to work closely together while sharing our respective spaces, to discuss things, and to smoothly perform collaborative work with the shared objects. Several studies have made attempts to create systems to share two remote spaces as one shared space [START_REF] Kuzuoka | Agora: A Remote Collaboration System that Enables Mutual Monitoring[END_REF][START_REF] Hirata | t-Room: Remote Collaboration Apparatus Enhancing Spatio-Temporal Experiences[END_REF][START_REF] Morikawa | HyperMirror: Toward Pleasant-to-use Video Mediated Communication System[END_REF]. These systems make it possible to share objects in a narrow area but do not permit complete sharing of the whole space. We aim to achieve an advanced media space that provides a seamless overlay between two remote spaces containing users and objects. This will enable users to share the objects in the two spaces and work closely together while sharing their respective spaces, to discuss things, such as furniture layouts, and to smoothly perform collaborative work with the shared objects. The enormous challenge in realizing such a media space is how to share two remote spaces with real objects and display the video to users naturally.

To meet this challenge, we have developed a method, called MIOSS, for overlaying two remote spaces through a mirror video. The MIOSS enables users to feel as if they are in the same room and to share objects in their respective spaces. Fig. 1 shows images of perspectives with a real mirror and MIOSS. The real mirror reflects the spaces of both user A and user B. With MIOSS, the display reflects the video of one space overlaid on the other space, and the users feel as if their space is overlaid on their partner's space. As an example of motion parallax, the yellow columnar object in user A's space is located behind user B on the display. The blue triangular object is located in front of user A on the display. The MIOSS system constructs 3D models of two remote spaces and displays the mirror video of a 3D model generated by overlaying the 3D models of the two spaces on a 2D display. The video provides geometrical consistency in occlusion, size, and positional relationships in the two remote spaces. Moreover, MIOSS imparts motion parallax through a mirror that adjusts to the viewpoint of the users. In this paper, we describe an implementation tool of MIOSS with a minimal setup as a first attempt to develop a MIOSS prototype. The setup comprises multiple Kinects and a 2D display in each user's space. We evaluated whether the implemented MIOSS enables users to recognize the exact positions of shared objects in the partner's space. The results show that the advanced functions of MIOSS-construction of 3D models of two remote spaces; reproduction of geometrical consistency in the position, size, and occlusion relationships among objects in the two spaces: and motion parallax to adjust to a user's viewpoint-enable users to recognize the exact positions of shared objects in the partner's space via the mirror video.

Related work

Several studies have proposed systems for sharing two remote spaces as one shared space. Agora [START_REF] Kuzuoka | Agora: A Remote Collaboration System that Enables Mutual Monitoring[END_REF] provides the shared space on a desk, and users can share real objects in each space on the desk. In t-Room [START_REF] Hirata | t-Room: Remote Collaboration Apparatus Enhancing Spatio-Temporal Experiences[END_REF], each space has a 2D display. Video of users and objects in front of one of the displays is projected and displayed on the 2D display in the other remote space. Users and objects directly in front of the 2D displays can be shared, but those not directly in front of them cannot be. HyperMirror [START_REF] Morikawa | HyperMirror: Toward Pleasant-to-use Video Mediated Communication System[END_REF] overlays the 2D image of a space on the 2D image of another space. It doesn't construct a 3D model of the remote spaces and doesn't reproduce the geometrical consistency in the position, size, and shielding relationships of real objects in two remote spaces. In addition, it doesn't impart motion parallax to adjust to a user's viewpoint.

On the other hand, 3D modeling of users and objects with multiple depth sensors, such as Kinect, has been attracting attention lately [START_REF] Newcombe | KinectFusion: Real-time dense surface mapping and tracking[END_REF][START_REF] Kainz | OmniKinect: Real-Time Dense Volumetric Data Acquisition and Applications[END_REF][START_REF] Maimone | Encumbrance-free Telepresence System with Real-time 3D Capture and Display using Commodity Depth Cameras[END_REF][START_REF] Maimone | A First Look at a Telepresence System with Room-Sized Real-Time 3D Capture and Large Tracked Display[END_REF][START_REF] Beck | Immersive Group-to-Group Telepresence[END_REF]. In addition, media spaces that display a 3D model of a remote space on a 3D display have been developed [START_REF] Maimone | Encumbrance-free Telepresence System with Real-time 3D Capture and Display using Commodity Depth Cameras[END_REF][START_REF] Maimone | A First Look at a Telepresence System with Room-Sized Real-Time 3D Capture and Large Tracked Display[END_REF][START_REF] Beck | Immersive Group-to-Group Telepresence[END_REF]. These systems aimed to connect the two spaces via the display as a bonded surface and join the two remote spaces.

Holoflector [START_REF]Holoflector[END_REF], which has a half-silvered mirror three feet in front of a large LCD screen, can superimpose 3D modeling data on an image reflected on the mirror. This lets the system create some interesting interactive effects, such as turning the user into a pixelated mannequin generated by 3D modeling, displaying a floating "hologram" above the user's outstretched palm, or raining little bouncing balls all around you. However, this system cannot overlay two remote spaces reconstructed by 3D modeling. MIOSS, the system proposed here, expands the functions of HyperMirror [START_REF] Morikawa | HyperMirror: Toward Pleasant-to-use Video Mediated Communication System[END_REF] to construct 3D models of two remote spaces and reproduce geometrical consistency in the position, size, and occlusion relationships among the objects in two spaces. In addition, it imparts motion parallax to adjust to a user's viewpoint. This research is the first attempt to create a system that can display a mirror video that reproduces geometrical consistency with motion parallax.

MIOSS

System summary

Fig. 2 shows the system architecture of MIOSS for user A (the architecture for user B is the same). In each space, there are two Kinect cameras, which capture RGB and depth images, and a 2D display or projector screen. The processing steps for presenting a mirror video on user A's 2D display are as follows:

 Measure user A's viewpoint position: The 3D position of the center of the user's eyes in a world coordinate system is measured as the user's viewpoint by using robust face-tracking technology with a memory-based particle filter [START_REF] Mikami | Memory-based Particle Filter for Tracking Objects with Large Variation in Pose and Appearance[END_REF].  Construct a 3D model of user A and user B: To construct the 3D model of the spaces of users A and B, the system uses the RGB and depth images from the Kinects and combines the 3D models of the spaces of users A and B in the same way as in previous research [START_REF] Newcombe | KinectFusion: Real-time dense surface mapping and tracking[END_REF][START_REF] Kainz | OmniKinect: Real-Time Dense Volumetric Data Acquisition and Applications[END_REF][START_REF] Maimone | Encumbrance-free Telepresence System with Real-time 3D Capture and Display using Commodity Depth Cameras[END_REF][START_REF] Maimone | A First Look at a Telepresence System with Room-Sized Real-Time 3D Capture and Large Tracked Display[END_REF][START_REF] Beck | Immersive Group-to-Group Telepresence[END_REF]. To construct a 3D model of a space, the system captures the RGB and depth images from the two Kinect sensors in each space. The system generates the two sets of 3D point cloud data from data captured from each Kinect using the of Point Cloud Library (PCL) function [START_REF]PCL (The point cloud library[END_REF] for each space. The two sets of 3D point cloud data are combined with calibration data generated by a preprocessing for calibration by Zhang's method [START_REF] Zhang | A flexible new technique for camera calibration[END_REF] between the two Kinects for each space. Finally, the two sets of 3D point cloud data for the spaces of users A and B are combined. At this time, the actual geometric consistency between the two spaces is realized in consideration of the positional relationship between the position and mounting posture of the Kinects in the spaces.  Generate the mirror image: With a 2D display used as a projection surface, the generated 3D model is projected in perspective to match the measured user's viewpoint. At this time, the world coordinate systems of the 3D position of the user's viewpoint and the 3D model are converted into the same coordinate system. Thus, mirror video on the display is implemented.

Fig. 2. System architecture of MIOSS.

Implementation

Using the above-described methods, we implemented a prototype of the MIOSS mirror interface. The development environment comprised two Kinects with VGA level resolution (640  480) of the RGB and depth images in each space, a computer with an Intel Core i7-3960X CPU and 16 GB of memory, and a NVIDIA GeForce GTX580 graphics board. The implementation results are summarized in Table 1, where "delay time of viewpoint movement" is the time from the user's viewpoint position's moving to the time the motion parallax appears in the video and "delay time of camera image" is the time until the captured video appears. In this regard, the prototype sends the RGB and depth image data from the Kinects to the partner's system directly via a non-computer network. The "delay time of camera image" has no network delay time for sending the data in this case. MIOSS expands HyperMirror [START_REF] Morikawa | HyperMirror: Toward Pleasant-to-use Video Mediated Communication System[END_REF] with two new functions. First, it constructs 3D models of two remote spaces and reproduces geometrical consistency in the position, size, and occlusion relationships among the objects in two spaces. Second, it imparts motion parallax to adjust to a user's viewpoint. We conducted experiments to examine whether the new two functions in MIOSS contribute to the user's recognition of the precise positions of objects in the partner's space. We set the following three experimental conditions as within-subject factors.

 2D condition: Mirror video of overlay of the 2D image of a space on the 2D image of another room (same as HyperMirror [START_REF] Morikawa | HyperMirror: Toward Pleasant-to-use Video Mediated Communication System[END_REF]). The video doesn't reproduce the geometrical consistency and doesn't impart motion parallax to adjust to a user's viewpoint. The setting of a user's viewpoint is where the image is displayed when the user is in the center of the room. As a method to generate the video for the condition, only the user and the objects in the space are extracted from the RGB image using depth information. The extracted user and objects are overlaid on the partner's RGB image.  3D condition: Motion parallax is excluded from MIOSS. The mirror video realizes the actual geometric consistency. The setting of the user's viewpoint position is where the image is displayed when the user is in the center of the room.  MIOSS condition: MIOSS is used. The mirror video realizes actual geometric consistency and motion parallax. We evaluated the effect of the repetition of the geometric consistency in the occlusion, size, and positional relationships in the two remote spaces by comparing the 2D condition with the 3D condition. We evaluated the effect of the repetition of the motion parallax by comparing the 3D condition with the MIOSS condition. Moreover, we evaluated the multiple effects of the repetition of the geometric consistency and the motion parallax by comparing the 2D condition with the MIOSS condition.

The experimental setup is shown in Fig. 3. The participants entered adjacent rooms (400 cm  350 cm) divided by a curtain. They were allowed to move freely within the area (400 cm  250 cm) 100 cm away from the screen. There were 100-inch (125 cm  221cm) screens placed 60 cm above the floor in front of the curtain in each room. The mirror video, which is 80 inches (108 cm  172 cm), was projected onto the screens from the projector. Two Kinects were installed at the top of the screen on either side. Five objects were positioned randomly in the space where there was no participant. The objects were photographs of real furniture and a bicycle of actual scale pasted to cardboard boxes (Fig. 4). There were three different combinations of five pieces of furniture (the total number of the pieces of furniture was fifteen). They were used as the objects for each condition randomly. The experiment began with the subject standing in the center of the space. At a signal to begin, the mirror video was output. The subject was given three minutes to write down the positions and sizes of the five objects in the room plan. The room plan has lines that indicate intervals of 5 cm. To minimize order effects, the three experimental conditions were used randomly. Each pair of participants used a different set of objects in each condition. After executing the experiment in each condition, the participants filled in a questionnaire for subjective evaluation (six-point Likert Scale) of their impression of the ease of recognizing the objects' positions. Sixteen persons (12 males and four females in their 20s) participated in the experiments. To evaluate how accurately the subjects were able to recognize the positions of the objects, we calculated the average error for all subjects between the center position reported by the subjects and the actual positions. We calculated the average error in the lengthwise direction, i.e., the direction perpendicular to the screen, and the crosswise direction parallel to the screen. The results are shown in Fig. 5. To determine whether experimental conditions made a difference in the position-recognition error of object's position of lengthwise and crosswise directions, we performed a one-way repeated factorial analysis of variance. The results showed a significant difference between experimental conditions (F(1,45)=3.55, p<.05 for lengthwise direction; F(1,45)=2.51, p<.10 for crosswise direction). Next, we performed multiple comparisons using the Tukey-Kramer method to identify differences between pairs of conditions. These tests showed that there are significant differences in the perception error of position in the lengthwise direction and that differences in the perception error of position in the crosswise direction trended to appear only between the 2D and MIOSS conditions (p<.05 for lengthwise direction; p<.10 for crosswise direction). The results demonstrate that position-recognition error was smaller for the MIOSS condition than for the 2D condition.

Results of recognition of position

Results of subjective evaluation

The average score of participants' subjective evaluations for "ease of recognition" is shown in Fig. 6. We performed a one-way repeated factorial analysis of variance for the item to determine whether experimental conditions affected the values. Since the analysis showed a marginally significant effect of experimental conditions on the evaluation (F(1,45)=2.57, p<.10), we performed multiple comparisons using the Tukey-Kramer method. A difference trend was found for the "ease of recognition" between the 2D and MIOSS conditions (p<.10). The average subjective score of the item of "ease of recognition" in the MIOSS condition is very high (4.8) and 1.2 score higher than in the 2D condition.

Discussion

In the results of the experiment, there was no difference in the average error of recognition of the object's position and subjective evaluation values between the 2D and 3D conditions. In contrast, the result showed that the average error of recognition of the object's position in the MIOSS condition is smaller than in 2D condition. The subjective evaluation of "ease of recognition" in the MIOSS condition was higher than in the 2D condition. The motion parallax, in addition to the reproduction of geometric consistency, is effective for enabling users to recognize an object's precise position. In the MIOSS condition, the average error of the recognition in the lengthwise direction was about 13.5 cm and that in crosswise direction was about 19 cm. The errors are very small. When a person observes an object that is directly in front of his/her eyes and writes the position on a sketch of the room, a little error is likely. In addition, the average subjective score of the item of "ease of recognition" in the MIOSS condition was very high (4.8). From the above, it is believed that users can recognize the position of an object accurately with MIOSS. Therefore, these results suggest that the reproduction of geometric consistency in video is, by itself, not sufficient for recognition of the precise position of objects in the partner's space. The motion parallax, in addition to the reproduction of geometric consistency implemented in MIOSS contributes to user's recognition of the precise position of objects in the partner's space. In this research, the prototype of MIOSS was implemented with a minimal setup with a 2D display (screen); it does not impart stereoscopic indications by means of monocular parallax with a 3D display. However, the results suggested that the motion parallax alone is quite sufficient for users to be able to recognize the position of objects in the mirror image.

Conclusion

We aim to create a media space that can overlay two remote spaces. We presented MIOSS, which enables users to feel as if they are in same room through the mirror and thereby to naturally share objects in two spaces. We developed a prototype of MIOSS that imparts motion parallax through a mirror that adjusts to the viewpoint of the user, in addition to providing geometrical consistency in the occlusion, size, and positional relationships in the two remote spaces. Experimental evaluations with the implemented MIOSS showed that the video expression of the geometric consistency in the video and motion parallax enables users to recognize the exact positions of shared objects in the partner's space via the mirror video. In future work, we plan to evaluate the effect of MIOSS in terms of the smoothness of remote cooperative work in detail with a conversation analysis.

Fig. 1 .

 1 Fig.1. Illustrations of real mirror and MIOSS.

Fig. 3 .Fig. 4 .

 34 Fig. 3. Experimental equipment. Fig. 4. Examples of objects used in the experiment.

Fig. 5 . 6 .

 56 Fig. 5. Average perception error of position. Fig. 6. Average score of subjective evaluations reported by subjects and the actual positions.

Table 1 .

 1 Performance of prototype of MIOSS

		Frame rate	Delay time
	Camera image	About 15 fps	About 500ms
	Viewpoint movement	About 15 fps	About 500ms


Adrian Gradinar
email: a.gradinar@lancaster.ac.uk

Daniel Burnett
email: d.burnett@lancaster.ac.uk

Paul Coulton
email: p.coulton@lancaster.ac.uk

Ian Forrester
email: ian.forrester1@bbc.co.uk

Matt Watkins
email: matt.watkins@wearemudlark.com

Tom Scutt
email: tom.scutt@wearemudlark.com

Emma Murphy
email: e.murphy@gsa.ac.uk

Perceptive Media -Adaptive Storytelling for Digital Broadcast

Keywords: Adaptive narrative, digital storytelling, context-aware media, perceptive media, perceptive radio

Storytelling techniques within traditional broadcast media have not made major advances in recent years due to the linear and relatively rigid approach to narrative despite advances in the technology that delivers the content. This research proposes the concept of 'perceptive media' in which the content creators have at their disposal different tools and sensors to allow for the subtle adaption of the narrative without any direct interactions from the audience members. The concept is demonstrated through the creation of a 'perceptive radio' that is able to play specially designed content that adapts to the physical and social context in which the radio resides.

Introduction

The storyteller greets the group slowly easing them into a relaxed ambiance where everyone is preparing to enjoy a well-told tale. As the story progresses, the storyteller adapts it to the particularities of the location and the group, making use of specific expressions, sayings or habits, referencing landmarks and places in the local vicinity to ensure the story resonates with the audience. The narrator also provides a warm welcome as more listeners join in, as well as becoming more engaged with the audience if their attention is drawn away from the story. It is through the use of these refined techniques, a personalized, unobtrusive storytelling practice is achieved, one where the subtle changes used by the storyteller contribute to the overall immersion level of the audience. In a similar vein, a well-versed stand-up comedian adapts their show to the specifics of the location of the theatre where the performance is taking place, tailoring the jokes around the audience and own perception of how well the audience is engaging with the show. Whilst the show is generally regarded as a performance, with an entertaining lead actor, the audience is experiencing a narrative given by a professional storyteller.

Despite the rapid pace of technological development across different mediums, broadcast storytelling content is still inflexible in comparison to these oral traditions. One medium that can adapt is digital games where game developers often create quite complex and twisting stories in which the player's actions, across diverse situations, directly influence the progression of the story as well as the evolution of the character and thus deliver a unique experience to each individual player (Mass Effect franchise 1 , TallTale: The Walking Dead2 , Alpha Protocol3 ). Whilst this technique has also been adapted to theatre by companies such as Punchdrunk4 , it has yet to be seen in traditional broadcast media.

The main advances we have witnessed recently in broadcast media have only affected the way that we consume the digital content (TV, stream box, mobile, laptop) or how it is being delivered (on-demand media versus traditional media). Whilst online voting can change the outcome of a TV episode or show, no real advances have been made around how program makers are looking at making their content more dynamic and adaptable. Therefore, this research explores different ways in which content creators can start thinking about how they may produce adaptable stories, by making subtle changes to the storyline based on the context in which the listeners are consuming the media. In doing so, the content creators are generating a new form of media that within this research we referred to as 'perceptive media'.

Since there is little direct experience of creating such media, a research through design methodology [START_REF] Gaver | What should we expect from research through design?[END_REF] has been used to facilitate an exploratory process in which different technologies are used independently and concurrently to gather contextual information about the current context of the audience in order to influence specially created media. To this end various physical and digital sensors have been encapsulated into a physical device that is able to deliver this dynamic radio content and which we refer to as 'perceptive radio'.

Perceptive Media

Unlike interactive narrative, "in which users create or influence a dramatic storyline through their actions" [START_REF] Riedl | Interactive Narrative: An Intelligent Systems Approach[END_REF], 'perceptive media' looks at narrative from a different perspective; it adapts a story to the audience by using information about them, gathered through the use of a range of sensors and sensing technologies, whilst shaping the story within the predefined scope set by the storyteller. If the goal of the interactive narrative is "to immerse users in a virtual world such that they believe that they are an integral part of an unfolding story and that their actions can significantly alter the direction or outcome of the story" [START_REF] Riedl | Interactive Narrative: An Intelligent Systems Approach[END_REF], in the case of the 'perceptive media', the overall story arc does not change, it is simply varying the more ambient parts of the narrative to create an engaging experience for the listeners. Thus these changes may not be immediately apparent to the user and rather they are subtle and awareness may develop slowly during the course of the broadcast. Therefore, 'perceptive media' attempts to bridge the gap between the 'flexibility' of the storyteller and the 'rigidness' of the broadcasted story delivered. The technologies employed take advantage of the implicit and explicit data the audience is generating and, in doing so, it redefines narrative as a set of logical attributes (variables), which could be moulded into different experiences. It is through the creation of adaptable stories and new experiences that the concept of 'perceptive media' is achieved.

Since the story has to adapt to the contextual information gathered by the available sensors, new requirements are being placed on content creators. Whilst they have the unique opportunity to create new experiences, they are also required to generate the essential materials to cover all possible scenarios for a particular story. Each sensory output needs to be thoroughly considered before being used within a broadcast and it is within the responsibility of the content creators to ensure the correct usage of the sensors.

The Perceptive Radio

Currently, the 'perceptive media' concept takes the shape of a radio, that expands on the capabilities and content of the original Perceptive Radio developed by the BBC R&D Department at MediCityUK in 20135 . Presently the range of sensors available consists of a microphone, used for noise cancellation, a camera, used to detect the number of people facing the radio, and a mobile phone, which is used to locate the radio. Based on the currently obtained information, extrapolated data is easily acquired, such as the weather, 'felt' temperature, 'real-feel' temperature or the time of day. Every piece of information could easily contribute to an even deeper personalisation level.

All the contextual information gathered through the sensors is passed to the radio, which employs a node.js server running on top of an Ubuntu distribution and delivering independent access to the sensors through an application program interface (API) built in JavaScript. The current setup was chosen to allow for the development of an easily expandable system, where other sensors could be effortlessly integrated. Furthermore, as the API is built using one of the most commonly used programming languages6 it permits for the rapid prototyping of new ideas content creators could design.

The final aim of the 'perceptive radio' is to demonstrate that the linear storytelling techniques developed within traditional broadcast media can be raised to a higher level, where contextual information can have a major contribution to the overall immersion level of the audience. The generated materials and concepts of this research will be made publicly available to encourage content creators to think of new ways in which digital stories are produced and delivered to the audience.

A Campfire Story

To demonstrate the notion of 'perceptive media' to both audience and content producers, the current prototype uses a storytelling narrative in the form of a 'campfire story', in particular an adaptation of one of the most well known Aesop's fables: The Two Travellers and the Farmer. The first contextual information gathered by the radio is its own location, by using the GPS position provided by the mobile phone. Based on this location, data such as the current weather and 'felt' temperature are obtained from online weather services. The time of day is also acquired from the internal clock alongside with the number of people currently within the sight of the camera. Based on this data, the story is dynamically generated. The 'campfire story' starts by greeting the listeners acknowledging their numbers, the time of day and 'felt' temperature. During the play, the radio monitors the activity of the listeners and the 'virtual storyteller' greets the listeners as they walk in or out of the room.

Similar to the original Aesop's fable, the 'virtual storyteller' asks each traveller about where they came from. Since the radio already has the contextual information about the location of the broadcast, the replies given by the travellers in the story reflect the current location. This is a subtle adaptation of the story, one that might not be perceived by all members of the audience; but, if registered by some of the listeners, it could enhance the overall experience.

Conclusion

The current iteration of this research introduces the concept of 'perceptive media', a new type of broadcast media, which makes use of contextual information provided through a range of different physical and digital sensors, to create a more engaging experience for the listeners by simply varying some of the ambient parts of the narrative. To demonstrate this concept a 'perceptive radio' has been developed. Through the use of a revised fable, the radio delivers an adapted narrative based on the location of the play, number of people in the room, time of day and weather data collected through the available sensors. In future work, the 'perceptive radio' will go under scrutiny from both content creators as well as the audience listening to the plays and conclusions will be drawn on the impact the 'perceptive media' makes on both categories involved.

http://masseffect.bioware.com/

https://www.telltalegames.com/

http://uk.ign.com/games/alpha-protocol/

http://punchdrunk.com/

http://cubicgarden.com/2013/05/22/perceptive-radio/

http://www.tiobe.com/index.php/content/paperinfo/tpci/index.html


Manfred Tscheligi

Sebastian Egger

Peter Fröhlich

Cristina Olaverri- Monreal

Georg Regal

Technology Experience Research: A Framework for Experience Oriented Technology Development

The optimization as well as exploitation of various aspects of user experience is crucial for future technological innovation and adoption. As a consequence of individualization, industrialization and lifestyle orientation, user experience is becoming more and more a major paradigm in the industry as well as in research & technology organizations. This applies at the level of products (goods, services), at the level of (public) technical infrastructures as well as on the level of human oriented innovation cultures and approaches. Based on several years of experience in applied HCI research the Business Unit Technology Experience within the Innovation Systems Department at the Austrian Institute of Technology (AIT) has been established as a horizontal unit to bridge between innovation in technological infrastructures and the diverse needs of users, costumers or diverse infrastructure contexts. Providing different viewpoints of technology experience and applied HCI thinking is a vehicle to facilitate improved levels of experiential quality.

1

Viewpoints towards a Business Agenda Specific application areas and application situations comprise specific interaction contexts, which leads to a comprehensive concept of contextual experience. Over the past years, the field of Human-Computer Interaction (HCI) moved beyond the desktop and explored new forms of interaction in different contexts. An in-depth understanding of contextual characteristics and the focused orientation of future experience approaches are the prerequisite for mature applications and technologies. Contexts are built by a variety of technological building blocks. This demands a structured integration of technology experience into development cycles as well as strong movement towards experience oriented thinking rather than pure technological orientation.

An applied research environment has to be supported by a clear definition of dedicated business cases. Institutional Experience deals with experience-oriented strategies, methods and tools within organizations. Technology Experience has to be implemented within the organizations in the right way. Current internal mechanisms need improvement under the regime of a user and experience driven mindset.

Experience Innovation Scouting delivers detailed needs as a prerequisite for successful technologies of the future. Supporting the detailed and contextual understanding of experience needs is a major element in an optimized user-driven development strategy.

Experience Creation is transforming requirements, needs and contextual insights into tangible experiences (interfaces) to allow access to the different features of a technological system. There is growing awareness that future market success will highly depend on the quality at the interface level as well as on appropriate ideas for future interaction approaches.

With Experience Trials new experience approaches combined with different technological building blocks call for effective and methodological experimentation and evaluation approaches. There is still a gap between a mature setup of such studies and the current practice in technological development.

Viewpoints towards a Research Agenda

The Unit is organized in four research streams. Social and Collaborative Experience aims to enhance the quality of experience for joint activities using various technologies, with specific technologies as well as induced by technologies. The enhancement and focused consideration of personal values in the existing as well as upcoming information and technology society is forming the second research stream on Personal Value Enhancing Experience. Users seek to achieve their values and technological artifacts are used to deliver these values. Technology Experience should support different values at the user side and gain understanding of the importance of different values from the perspective of an individual user. In addition we are living in a mobile society where technological artifacts are ubiquitous. However, the very essence of needs of users on the move (e. g. intermodal transport information), characteristics of specific user groups (e. g. elderly users on the move) or enhanced experiences of specific mobility situations still offers some challenges. So the research stream of Mobile User Experience is dedicated to enhancing the experience of different situations of users on the move. The Experience Foundations research stream will complement theses more contextual viewpoints by investigating basic aspects such as key ingredients and understanding of technology experience, future methodological approaches (e.g. including the perspective of Quality of Experience) as well as emerging interaction paradigms.

Conclusion

The efficient synergy of these two levels of viewpoints allows a methodological driven research and innovation strategy. Technology experience research services are positioned between industrial and research technology providers and different kinds of end users and user groups, which will be more motivated to accept, utilize and invest in technologies with a higher degree of user experience quality.

.


Hyeonjung Ahn

Sangwon Lee

Small Community Size of Private SNS for Bonding Relationship: Development of a Research Framework

Keywords: Private SNS, Public SNS, community size, bonding relationship, bridging relationship 1

Since SNS has become an important tool for social relationship and information sharing, numerous studies regarding SNS have been conducted in various domains of social science. Among many kinds of SNSs, we have focused on private SNS, which is especially appropriate for communicating with close acquaintances to bond relationship. Firstly, we investigate the difference of communication patterns between public SNS and private SNS to review and clarify key features of private SNS. To address the issues on ideal community size of private SNS, the present study examines some private SNSs limiting the number of friends. With these kinds of SNSs, we secondly clarify whether this function will be useful in managing the users' relationships for 'strong ties' with emotional closeness. As a preliminary study on private SNS, we suggest research framework based on other studies about research methods to analyze SNS usage patterns. Through online questionnaire survey, we expect to attain the results of the research questions regarding private SNS.

Introduction

Nowadays, social network services (SNS) have become a major social media with much impact on individual's daily life. Numerous people are using SNS for various purposes, including social relationships and information sharing with others through computer-mediated communication. Facebook is one of the most popular SNS, with 1.3 billion users across the world. However, some problems including privacy risks, information overload, and uncountable online friends arose in using some types of SNSs [START_REF] Dwyer | Trust and privacy concern within social networking sites: A comparison of Facebook and MySpace[END_REF]. In this paper, we call those SNSs, which are beneficial for bridging relationship and with no restrictions to be a friend online, to public SNS (e.g., Facebook, Twitter). [START_REF] Steinfield | Social capital, self-esteem, and use of online social network sites: A longitudinal analysis[END_REF] regard the social networking in Facebook as diverse collection of "weak ties" [START_REF] Granovetter | The strength of weak ties[END_REF] which are good for sharing new information [START_REF] Steinfield | Social capital, self-esteem, and use of online social network sites: A longitudinal analysis[END_REF]. In contrast, private SNS is designed to communicate with only the close friends such as family and close friends for bonding relationship. 'Path', 'Band', and 'Kakao Group' are the most representative examples of private SNS. 'Band' is the most popular private SNS launched by NAVER, a popular search portal company in Republic of Ko-rea, and has over 12 million domestic users [4]. 'Band' also planned to extend its service to the United States in 2014 because they noticed foreign users' needs of privacy on SNS arising from aforementioned problems. Similarly, Kakao Group's number of users has increased by over 4 million in six months with its linkage with Kakao Talk [4]. These figures imply that the SNS user's other needs that are hard to be satisfied by using public SNS.

In a few studies, researchers have raised a question about the community size for effective offline relationships and online relationships. Dunbar insisted that 150 people is the most desirable number of community size for individual's effective relationship with others, and 150 is well known for Dunbar's number [START_REF] Hill | Social network size in humans[END_REF]. Later, some other researchers suggested that Dunbar's number is only valid in offline relationships, and that it is possible to maintain a relationship with 200 to 300 people in social networks. This is dubbed a new magic number [START_REF] Zhao | Being rational or aggressive? A revisit to Dunbar's number in online social networks[END_REF]. In the current study, we firstly aim to find out the difference of communication patterns between public SNS and private SNS to clarify key features of private SNS. We will mainly refer to the studies about SNS usage patterns on Facebook to compare them with that of private SNS. Additionally, we examine whether the intimacy between friends on private SNS is influenced by the constraints on community size of private SNS such as Path and Daybe. Therefore, we attempt to answer to the following research questions:  RQ1. What is the difference of communication patterns between public SNS and private SNS?  RQ2. Do constraints on community size of private SNS have an impact on the more emotionally close relationship?

As a preliminary study on private SNS, we focused on the key trait of the community size on the SNS. Through our suggestion of research framework, we expect to obtain the results of these research questions.

Background

Social Network Service

SNS is one of the most effective communication methods that allow the user to create his/her own profile online, and to share any information with other users in social networking sites [START_REF] Ellison | Social network sites: Definition, history, and scholarship[END_REF]. Each of the social networking sites including 'Cyworld', 'Facebook', and 'Twitter' has its own targets and concept. The effect of these SNSs became much bigger with the emergence of smart phones in 2007 making our lives more accessible to the Internet anytime and anywhere. A large number of researchers have raised questions regarding how the SNS could be utilized to maintain individual social relationships. Social capital theory is very essential in understanding and studying social networking to build and promote one's relationship in real or virtual environments. The social capital is the resources derived from social relationship [START_REF] Portes | Social capital: Its origins and applications in modern sociology[END_REF] and it classifies the type of relationship into two types; bridging and bonding social relationship [START_REF] Putnam | Bowling alone: The collapse and revival of American community[END_REF][START_REF] Woolcock | Social capital: Implications for development theory, research, and policy[END_REF].

Bridging social relationships is considered as a collection of "weak ties" [START_REF] Granovetter | The strength of weak ties[END_REF] that do not show intimacy among people. On the contrary, bonding social capital is regarded as a collection of ''strong ties" [START_REF] Granovetter | The strength of weak ties[END_REF] and close social relationship among close friends or family. However, most of SNSs are still beneficial in maintaining weak ties rather than strong ties [START_REF] Donath | Public displays of connection[END_REF]. These SNS users can use their relatively big sized relationship to share any information that their friends and themselves do not have.

In the present paper, we have apparently divided types of SNS into public SNS and private SNS. Facebook and Twitter are public SNS, which are effective tools for bridging social capital online. the contrast, Band and Path are private SNS, for they are mainly used to bond one's social capital online. Most of these private SNSs are designed to communicate with family, close friends, and even neighbors, according to their own concept of the services. Among these diverse private SNSs, we have mainly focus on the private SNSs which give constraint to the community size such as Path and Daybe to investigate RQ 2.

Community size for effective relationship

Some researchers in the field of social science have studied about community size for effective relationship in real and virtual environments. Dunbar's number is one of the most popular theories demonstrating that a maximum of 150 people is the most appropriate number of group size to effectively maintain personal relationships with others [START_REF] Hill | Social network size in humans[END_REF]. Several social network services were designed based on this theory for bonding social capital. 'Path' and 'Daybe' have similar function of limiting the maximum number of friends up to 150 and 50, respectively. Path limits the size of social network up to 150 friends to promote relationship based on the Dunbar's number theory [START_REF] Hill | Social network size in humans[END_REF]. Even though 'Daybe' discontinued its service in the latter half of 2014, it limited the maximum number of friends to 50 people. If the number of members exceeds 50, the member who has communicated and interact the least with the user is eliminated automatically in order. This is a very simple function but differentiation strategy which is different from other private SNS in that it can grant the users some cognition to strengthen existing weak ties with members. Other researchers insisted that Dunbar's number can be applied to social capital in real environments and suggested a new magic number ranging from 200 to 300, demonstrating individual sustainable social networking size online [START_REF] Zhao | Being rational or aggressive? A revisit to Dunbar's number in online social networks[END_REF]. However, this result is valid in bridging relationships rather than bonding them online. In the current study, we focused on the purpose of forming solid relationship not bridging social capital on private SNS.

Development of a Research Framework

We target SNS users who are currently using Facebook and more than one private SNS together among the following private SNSs; Band, Kakao story, Kakao Group, and Path. As a research method, we suggested online questionnaire to be distributed to over 200 participants to collect the following data; demographic data, communica-tion patterns of private SNS, and the degree of intimacy before and after using private SNS. We plan to design the questionnaire about private SNS usage by including the following contents with the reference of 'Facebook intensity scale' developed for measuring user's Facebook usage patterns [START_REF] Ellison | The benefits of Facebook "friends:" Social capital and college students' use of online social network sites[END_REF] and 'Bonding Social Capital Scale' validated by [START_REF] Williams | On and off the'Net: Scales for social capital in an online era[END_REF] [START_REF] Williams | On and off the'Net: Scales for social capital in an online era[END_REF].

 Average private SNS usage time per day and per week  The number of friends and groups on private SNS and public SNS, respectively  Private SNS users' satisfaction regarding the aspects of bonding relationships  The degree of intimacy before and after using private SNS  The effectiveness of 'limiting the number of friends' function such as Path and Daybe  Personal opinions regarding the ideal community size on private SNS for "strong ties"

For example, the following items are filled out based on 'Bonding Social Capital Scale' [START_REF] Williams | On and off the'Net: Scales for social capital in an online era[END_REF] to obtain data about 'the degree of intimacy before and after using private SNS' with the Likert scale ranging from 1(strongly disagree) to 5(strongly agree).

 There are several people on private SNS that I can trust to solve my problems.

 If I need an emergency loan of $100, I know someone on private SNS that I could turn to.  There is someone on private SNS I could turn to receive advice about making very important decisions.  The people I interact with on private SNS would be good jog references for me.  I do not know people on private SNS well enough to get them to do anything important.  I feel I am part of the private SNS community.

Prior to the online survey, we will conduct a pilot test to revise the contents in the questionnaire. After analyzing the collected data through SPSS, we expect to obtain results about different communication patterns between public SNS and private SNS and higher sense of closeness between friends after using private SNS.

Discussion & Conclusion

In the present study, we focus on private SNSs, which are designed to promote relationship online, unlike from the public SNS. We firstly compared public SNS and private SNS with regard to communication and usage patterns in order to clarify the different effect of communication between them. Among many kinds of private SNSs, we examine the private SNSs having the function of limiting the maximum number of friends. With this kind of SNSs, we raised a question about whether the function is beneficial for users in increasing their 'strong ties' in social networks. With this question by extension, we intend to find out desirable community size on private SNS in our future study.

Through this study, we expect to contribute private SNS service providers to innovate and improve their services for relationship promotion online. It will result in taking their relationship with others to next level most effectively with higher satisfaction levels. The results can be also utilized in social network services to develop easier way to expand and form solid social network.

Acknowledgements

This research was supported by the Ministry of Education, South Korea, under the Brain Korea 21 Plus Project (No. 10Z20130000013) and Basic Science Research Program (No. NRF-2014R 1A 1A2054531).


Máté Köles
email: kolesm@erg.bme.hu

Károly Hercegfi
email: hercegfi@erg.bme.hu

Balázs Péter Hámornik
email: balazs.hamornik@erg.bme.hu

Emma Lógó

Bálint Szabó
email: szabobalint@erg.bme.hu

Anita Komlodi
email: komlodi@umbc.edu

Hercegfi Károly

Anita Komlódi

Cooperation in Real-Time Using a Virtual Environment

Keywords: virtual reality, cooperation, problem solving

des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

Non-verbal communication is just as important as verbally transmitted information in real world scenarios. If the social interaction takes place in a virtual world, the number of available non-verbal cues becomes limited. This is a problem, since partial or incomplete non-verbal signals can lead to misinterpretation and ultimately hinder cooperation [START_REF] Cheshin | Anger and happiness in virtual teams: Emotional influences of text and behavior on others' affect in the absence of non-verbal cues[END_REF]. The more sources available the easier it is to disambiguate what the other person was trying to communicate. Also having congruent signals from these different channels will increase percentage of recalled information [START_REF] Buisine | The effects of speech-gesture cooperation in animated agents' behavior in multimedia presentations[END_REF] and create a more empathic feel towards the other person [START_REF] Ang | Effects of gesture-based avatarmediated communication on brainstorming and negotiation tasks among younger users[END_REF][START_REF] Bente | Avatar-Mediated Networking: Increasing Social Presence and Interpersonal Trust in Net-Based Collaborations[END_REF]. Collaboration in virtual spaces is currently limited in conveying important non-verbal information. Since registering and virtually recreating whole body movement (including facial expression) of an individual is not cost effective at this time, compromises have to be made. A selection of easy to implement non-verbal channels should be selected to enhance communication in virtual environments. Head orientation is a powerful cue that can signal social attention [START_REF] Langton | The influence of head contour and nose angle on the perception of eye-gaze direction[END_REF] Virtual environments may seem to be inherently inferior to real-life environments in case of cooperation, but that is not true for all aspects of the interaction. First of all, the laws of physics can be changed according to the goals of the cooperators. Inspection and theoretical modification of a heavy object for example is much easier to do in virtual space. And if the virtual space supports it, changes are instantly visible compared to a drawing on a paper. Also, some suggest that people can feel more liberated in virtual environments and express their character better than in real-life [START_REF] Stanilova | Survey on Verbal and Non-verbal Behaviors in Real and Virtual World[END_REF]. And at last but not least, geographic distances are not a problem anymore. Virtual team meetings can be held even if the members are on different continents.

The Virtual Collaboration Arena (VirCA)

The demonstration will feature the Virtual Collaboration Arena (VirCA) as the system responsible for the virtual environment. It is a loosely coupled, modular system capable of supporting a wide array of tasks. From remote robot control [START_REF] Galambos | VirCA as Virtual Intelligent Space for RT-Middleware[END_REF]

Demonstration

The virtual environment

The interaction will take place in a 3x3m virtual room designed to represent a tourist office. It contains a map of Budapest, posters and flyers about different sights and activities and jointly editable documents (Fig. 1.). It also has a few decorative items (a plant, a trash bin and a window) to create a more natural feel. The posters contain information about the location of the given activity with opening hours and entry fees (if any). They are grouped into four different categories by symbols: sights, baths, clubs and restaurants. Both participants are able to move or highlight the posters. The editable documents serve as notepad pages, where ideas can be written down. They can also be used to add activities not represented by the available posters. Each participant is represented by a single colored head. The reason behind the simplicity of the avatars is the following. As established in the introduction earlier, the more detailed the avatar, the more equipment and resources are required. These simple avatars are able to convey head orientation which is a very important social cue [START_REF] Langton | The influence of head contour and nose angle on the perception of eye-gaze direction[END_REF], pointing gestures (for clarifying common attentional objects) and also intonations through real-time voice chat.

Brief description of the task

The demonstration aims to replicate the first part of an information management task.

There will be two phases. The training will introduce the participant and the audience in Bamberg to the virtual space and the possible forms of interaction. For the actual collaborative part of the task, we will connect live to another user situated in Budapest. From that point on, users will have to solve a task that simulates creating a holiday plan for a tourist group for a weekend at Budapest. We decided to include a few conditions that should be met by every successful solution. The exact instructions are: "Create a holiday plan for two days for a foreign tourist group who are around your age. Make sure to include in your plan a trip to a bath and a pub. Also, both days should end at a club. Suggest places for lunch and dinner for both days; they receive breakfast at their hotel. Try to fill both days with classic tourist attractions. Create a plan that is varied, yet manageable. Display the final plan in the table located on the front wall."

The task requires participants to decide together on a plan that satisfies most criteria.

The posters contain all the information required to solve the task. No existing knowledge of Budapest is required. However, there are some activities that are not available on weekends so they have to be mindful of their choices. All posters that become part of the plan should be placed in a timetable on the wall. The task will run until the plan is finished or time for the demonstration runs out. A brief evaluation of the solution is given at the end.

Fig. 1 .

 1 Fig. 1. The virtual environment representing a tourist office with the avatars of the users in the middle.

  through virtual meetings to psychological experiments in spatial cognition [8]. It was developed by Cognitive Informatics Research Group of the Computer and Automation Research Institute of the Hungarian Academy of Sciences. Custom rooms and objects are easy to define and use. It support classic input devices as mouse and keyboard but also gaming controllers and motion tracking.

Acknowledgements. The present study was supported by the KTIA_AIK_12-1-2013-0037 project: Virtual NeuroCognitive Space for research and development of future immersive mediatechnologies (NeuroCogSpace). The project is supported by the Hungarian Government, managed by the National Development Agency/Ministry, and financed by the Research and Technology Innovation Fund. The authors thank Péter Baranyi and the 3DICC Lab of SZTAKI for organizing the project and supporting the VirCA virtual environment.


Janet C Read
email: jcread@uclan.ac.uk

Working with Child Participants in Interaction Design

Keywords: Participatory design, Teenagers, Child Computer Interaction, Evaluation, Tutorial

des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

The Child Computer Interaction (CCI) community has long advocated the active participation of children in its research and development practices [1]. When children are introduced into design and evaluation studies, there are ethical, practical and methodological concerns that need to be considered, indeed it was at Interact, in 2005, where these concerns were first discussed [2]. For many in HCI the thought of engaging with children, especially young children and teenagers, can be daunting. The IDC community, over the last 13 or so years, has developed methods and techniques, and has amassed a wealth of knowledge that can mitigate this concern. This tutorial delivers this knowledge to attendees in a lively interactive format from experts who have been at the forefront of training and instruction in CCI [3].

Learning Objectives, Content and Duration

Individuals attending this tutorial can be expected to be able to:  Plan, carry out and report design and evaluation studies with children  Understand the importance of ethical practices when children participate.  Use appropriate methods including verbalisation, survey methods, participatory design techniques and diary methods for technology report.  Appreciate where additional material can be found This tutorial will be for half a day. The expectation is that it will proceed as follows:

 9 -9.15 Intro to the instructors, brief introductions around the room  9.15 -9.45 Talking to children in evaluation studiesa lecture style presentation with video and audio and a short group activity will introduce retrospective think aloud, peer tutoring and participant observation [4].  9.45 -10.30 Surveying childrena group activity where participants will complete surveys including The Fun Toolkit [5], the ABCTT [6], the Group Sorter [7] and the This or That method [8]  10.30 -11 Coffee  11 -11.15 Diary methodsdiaries will be given out and explanations of how they can be used will be given [9]. The diaries will then be used as self report during the next activity and will be discussed again at the end.  11.15 -12.00 Participatory design using diaries to record activity. Participants will do a design activity as though they are children [10]. and consent and wrap up [11].

3

Audience and Reading List


Jaeun Yu

Gerard J Kim
email: gjkim@korea.ac.kr

Eye Strain from Switching Focus in Optical See-through Displays

Keywords: Optical see-through displays, eye strain/fatigue, usability, augmented reality, focus

The optical see-through (OST) display is one of the key enabling devices for augmented reality. Despite the latest craze such as with the Google Glass, there are still many ergonomic problems associated with the OST displays. One of the already well known such problem is the "refocusing" problem, in which the user has to switch one's focus between the distant real world and see-through display up front. Such refocusing, for one, is bound to cause significant strain and fatigue to the eyes. However, there are not many studies, nor guidelines devoted to this issue. In this preliminary work, we ran experiments to measure the degree for eye strain and its pattern at different refocusing distances and durations (or number of focused targets). The findings should serve as one guideline in designing OST glass based interaction and applications.

Introduction

The continued innovations and advances in computer vision, mobile/cloud computing and portable display devices have brought about a renewed interest in augmented reality (AR) as a prominent information visualization and interaction medium. In particular, since the recent introduction of the Google Glass [START_REF]Google Glass[END_REF], optical see-through (OST) displays are becoming more compact and fashionably designed, and thereby getting accepted to the mass users. Yet, there are some concerns as well [START_REF] Horn | Is Google Glass Bad for Your Eyes?[END_REF][START_REF] Ackerman | Could Google Glass Hurt Your Eyes? A Harvard Vision Scientist And Project Glass Advisor Responds[END_REF], and one such is the eye fatigue and even the potential to hurt the eye as the user has to make conscious effort to focus on the tiny display in the upper right corner of the glass (as in the case of Google Glass). More specifically, the use of OST displays unavoidably entails the frequent switch between looking into the real world and refocusing on the small display up front (or at distance to the virtual image plane). While this refocusing problem (and fatigue) is unavoidable, its detailed ergonomic effects need to be studied and known to reflect it into the interaction design involving the use of OST displays. However, aside from general literatures on various factors that can cause different types of eye fatigue, not many studies have been made in the context of this AR specific problem. With such motivation, we ran experiments to measure the level of fatigue caused by the frequent refocusing between real and virtual objects, and its relation to the focusing duration.

Related Work

Usability problems with OST displays are not new, e.g. due to its cost, weight, size, image quality and lowered brightness, distorted depth perception, mismatch in the resolution of the augmentation with that of the real world imagery, registration and calibration errors, incomplete masking by the augmentation, etc. [START_REF] Azuma | A survey of augmented reality[END_REF][START_REF] Rolland | Optical versus video see-through head-mounted displays in medical visualization[END_REF]. The recent introduction of Google Glass made quite a stir with its sleek and light-weight design, and has much improved the wearability aspect, however, many ergonomic problems still remain. While there have been almost no formal studies on the Google Glass itself, there have been few media reports of the potential eye strain problem [START_REF] Horn | Is Google Glass Bad for Your Eyes?[END_REF][START_REF] Ackerman | Could Google Glass Hurt Your Eyes? A Harvard Vision Scientist And Project Glass Advisor Responds[END_REF]. Huckauf et al. compared the visual search and focus switching tasks on between computer screens and OST displays, and confirmed the lowered performance on the OST displays. Furthermore, they also found that users tended to misjudge the target object depth, namely closer than the actual [START_REF] Huckauf | Perceptual issues in optical-see-through displays[END_REF].

Experiment 1: Fatigue caused at different refocusing lengths

Obviously, the fatigue from the refocusing task will be closely related and proportional to, among others, the refocusing distance. In this study, we are interested in the changing pattern of the fatigue level, e.g. whether it is approximately linear, exponential, saturating (e.g. log), step-like form and whether it is symmetric with respect to some nominal comfortable focusing distance. Based on the findings, we might limit the objects targeted for augmentation only to be within some nominal range of distance to minimize the eye strain. Five paid subjects, 3 men and 2 women with a mean age of 23, participated in the experiment. An experiment with one-factor (4 different refocusing distances) within-subject with repeated measures was conducted. The task was to focus at an object in the real world and refocus to information displayed on the Google Glass in which the virtual image plane is formed at about 2.4 m away from the eyes. The objects were placed at 6m, 3m, 1m and 30cm from the user making the refocusing distances, 3.6m, 0.6m, 1.4m and 2.1m, respectively. The user had to state whether the object in the real world and the information displayed on the glass matched or not (see Figure 1).

The fatigue level was measured indirectly by measuring the response time. (i.e. stating whether the information in the display matched or not) and through a survey. The task was repeated over four five-minute blocks after which a fatigue survey was completed. The level of eye fatigue can be measured in many ways, ideally through optometric measurements, physiological signals (e.g. EMG of eye muscles) or using eye tracking devices. However it is generally difficult to use such apparatus because the glass has to be worn. Instead eye strain can be indirectly assessed by other indicators such as degradation in task performance, immediate symptoms such as dryness or over-blinking, and after effects such as headaches and neck [START_REF] Sheedy | Visual Fatigue in Near Vision: Visual Fatigue[END_REF]. Figures 2 shows the average response time (for total of successive 200 trials) and answers to the survey (about the perceived fatigue and eye strain). As expected, the fatigue level was proportional to the refocusing length, where the least amount of fatigue was felt at the refocusing distance of 0.6m, and the most at 3.6m. The fatigue levels actually slightly dropped after 5~6 minutes but then rose sharply and steadily increased afterwards. No other clear trend of particular changing patterns, other than direct proportionality, was detected.

Experiment 2: Refocusing frequency vs. duration

Through the first experiment, we were merely able to confirm an obvious fact that the eye fatigue and eye strain increased according to the extended refocusing distance.

In the second experiment, we fixed the refocusing distance and varied the information amount at which to focus, namely one, three and five objects laid out vertically (similarly to the typical Google Glass menu). This way, we can compare the level of fatigue between when displaying little information but having to refocus several times vs. displaying more information at a time and focusing longer on them and having to refocus a less number of times. Again 5 paid subjects, 3 men and 2 women with a mean age of 23, participated in the experiment. Again the experiment with one-factor (3 different information amounts) within-subject with repeated measures was conducted. In the three treatments (presented in a balanced order), the user had to look at one, three and five real world objects and placed at 2.4m, refocus to the glass display and report if the objects matched to those in the glass display (see Figure 1). The user was given 20 minutes and the user performance was recorded (i.e. how many refocusing tasks could be accomplished and how much pieces of visual information could be processed).

Figure 3 illustrates the results and among the three treatments, the best performance (per effort/fatigue) was achieved by managing the refocusing and focusing duration with a block of three objects (ANOVA, F(2, 72) = 14.18, Tukey tests with p-values < 0.03). The results shows the refocusing distance and amount of information displayed need to be carefully modulated to improve general usability of OST displays. Best performance per effort/fatigue was obtained with the block of three objects.

Conclusion and Future Work

In this poster, we have conducted pilot experiments assessing the nature of eye strain and fatigue as related to the refocusing distance and how it might relate to the amount of visual information that need to be focused at one time and processed. The findings are still only preliminary as it requires more subjects and experimental conditions to derive more definite conclusions. The contribution lies in taking the first step toward quantifying ergonomic problems of OST displays in the context of AR, and showing directions for the future full scale experiments.

Fig. 1 .

 1 Fig. 1. The refocusing task using the Google Glass and measuring the associated fatigue level: (a) Experiment 1 (left), (b) Experiment 2.

Fig. 2 .

 2 Fig. 2. Average response time (for total of successive 200 trials) and cumulative score of the fatigue survey about the perceived fatigue and eye strain.

Fig. 3 .

 3 Fig. 3. Number of tasks accomplished (or amount of visual information processed) in unit time.Best performance per effort/fatigue was obtained with the block of three objects.

Acknowledgements. This work (Grants No.C0239066) was supported by Business for Academic-industrial Cooperative establishments funded Korea Small and Medium Business Administration in 2014.