We propose a methodology that enables measuring engagement of spectators in a social digital game combining physiological and self-reported data. As this digital game involves a group of freely moving people, the experience is filmed using a synchronizing technique that links physiological data with events in the game.
The goal of this methodology is to assess explicit and implicit measures of engagement of spectators during social digital games in a group of participants with motion tracking systems. In the context of games that are not confined within a screen, measuring the different dimensions of engagement such as physiological arousal can be challenging. The focus of the study is made on the spectators of the game and the differences in their engagement according to interactivity. Engagement is measured with physiological and self-reported arousal, as well as an engagement questionnaire at the end of the experiment. Physiological arousal is measured with electrodermal activity (EDA) sensors that record the data on a portable device (EDA box). Portability was essential because of the nature of the game, which is akin to a life-size pong and includes many participants that move. To have an overview of the events of the game, three cameras are used to film three angles of the playing field. To synchronize the EDA data with events happening in the game, boxes with digital numbers are used and put in the frames of cameras. Signals are sent from a sync box simultaneously to the EDA boxes and to light boxes. The light boxes show the synchronization numbers to the cameras, and the same numbers are also logged on the EDA data file. That way, it is possible to record EDA of many people that move freely in a large space and synchronize this data with events in the game. In our particular study, we were able to assess the differences in arousal for the different conditions of interactivity. One of the limitations of this method is that the signals cannot be sent farther than 20 meters away. This method is, therefore, appropriate for recording physiological data in games with an unlimited number of players but is restricted to a limited space.
Studying the experience of game spectators helps to better understand the positive and negative aspects of the game, and in turn, can help to improve its design1. Recent innovations in the gaming industry have allowed new types of experiences that move forward from traditional console-based gaming2. With digital games that use motion tracking systems that are not confined within a screen, audiences do not have to be positioned in a fixed spot anymore. This new reality creates challenges in the assessment of spectators' experience. The experiment was performed in the studio of the creators of the game but could be replicated in a laboratory setting or another environment that has enough space to fit the game.
The purpose of this methodology is to measure spectator engagement during a social digital game. More precisely, arousal, which leads to engagement, will be measured when the spectator has access to a web application that influences the gameplay. This method combines physiological and self-reported data. As this game is social and involves a group of people that move, the experiment is filmed. With the use of cameras and portable physiological devices, we were able to synchronize physiological data with events in the game. The portable devices (EDA boxes) are 3D printed boxes that are connected to electrodes that record physiological activity. The boxes have an ON/OFF switch, visual indicators, a microSD card slot and charging slots. The visual indicators help in case of troubleshooting. For example, these indicate whether the microSD is functional, show the state of the Bluetooth and Wi-Fi connections and signal whether physiological data are being recorded.
The use of physiological measures is a common and validated approach for measuring game engagement3. Physiological valence has been measured in the context of video games4. It has also been used in other research domains such as education5. Because emotional engagement is not observable and self-report can be biased, Charland et al. have used physiological arousal to assess emotional engagement in learners that were solving problems5. They used electrodermal activity (EDA) to measure physiological arousal, which is a widely used method6. EDA is the measurement of skin conductivity, which varies according to the differences in sweat gland activity3. This measurement is an important correlation to real-time emotional variations. EDA is associated with many constructs such as stress, excitement, frustration, and engagement7. Complementing EDA data with self-report responses are therefore recommended to associate the data with the right construct3. The Self-Assessment Manikin (SAM) is a self-reported pictographic scale that assesses three dimensions of emotion: valence, arousal, and dominance8. The current work used the arousal dimension, assessed using a visual 9-point Likert scale, ranging from calm to excited. Perceived arousal has been used in combination with physiological arousal7.
In traditional video games contexts, spectators are seated in a chair and stay more or less in the same position for the duration of the experiment. They are expected to look at a screen where the actions take place. This setting has been seen in previous games studies using physiological data9. In this case, it is simple to start the recording of the game at the same time as the recording of the physiological data10.
In the context of new digital games that are played outside of the screen, and in which participants stand and are free to move, traditional EDA recording might not be appropriate. The game used in this study is akin to a life-size Pong11. This game is composed of a ball and two paddles, each on an extremity of the playing field. Players move their paddle in order to push the ball from one end of the field to the other. In the version used for this research, the game is projected on the ground and players use their bodies as controllers for the paddles. Movement detection technology allows the paddle to follow the two players who are situated at opposite sides of the playground. An example of how the players prevent the ball from hitting the virtual wall behind them is presented in Figure 1. The game also involves spectators standing on the sides of the playground, who can use their smartphones to influence the gameplay. Using a mobile web application, spectators can vote for certain power-ups or obstacles that can either help or harm the players (e.g., less walls versus more balls, or modulating the speed of the ball). The option with the most votes wins.
In this study, we investigate the influence of interactivity on spectators. The conditions of interactivity are with or without smartphone. We compared the engagement of the spectators in these two conditions. A within-subject design was used for the interactivity condition, in order to assess the difference in arousal, and therefore in engagement. In the current study, groups of 12 people were ideal to promote ecological validity of the game12. two people as players and 10 as spectators. Only two EDA boxes were available for our study, so we had a total of eight groups which totalized 16 EDA data sets (two participants with EDA recording per group of 12). Each member of the public was randomly assigned to two games with access to their smartphone to influence the gameplay and one game without access to their smartphone. Game engagement literature suggests that giving many interactive options can lead to higher engagement13. Research in education has found that physiological arousal is a correlate of emotional engagement5. Building on game engagement literature and research in education, we hypothesized that giving the spectators access to interactivity will increase arousal which will in turn increase their engagement.
Contrary to studies about player experience, studies about spectators of a digital game rarely use psychophysiological measures. They are mostly done with questionnaires14, observation15, and interviews16. One difficulty of using psychophysiological measures with spectators is that they are often a group and their movements are less predictable than those of the players. This methodology uses multiple cameras to capture the participants and light boxes, enabling linking of participants video and physiological data.
As we used a within-subject design for the smartphone condition, each subject participated in two games with the interactivity condition, using their smartphone, and one game in the control condition, without the use of their smartphone. Synchronization of EDA data with the starts and ends of each game was therefore crucial to enable the assessment of the differences in each condition of interactivity. It would be impossible to start the recording of all the three cameras at the same time as the recording of the EDA on the spectators due to the dimensions of the room. To overcome that issue, we have used a new synchronization technique called wireless synchronization protocol for the acquisition of multimodal user data17. Bluetooth Low Energy (BLE) signals are sent from a sync box simultaneously to the EDA boxes and to light boxes (see Figure 2). The sync box is a 3D printed box with ON/OFF and auto/manual switches and a button. The manual function is used for testing the signals using the button. The signals are incrementing numbers that start at one and that are shown on the 3D printed light boxes. There numbers are shown to the cameras, and the same numbers are also logged on the EDA data file (see Figure 3). This allows synchronization of events happening in the game to variations in the EDA recordings. In our case, the events identified were the starts and ends of the three games. Then we could link the game to the condition and to the participant number. In this way, we identified which dataset corresponded to each condition.
The following section describes the protocol that allows the use of the technique developed by Courtemanche et al.17. We adapted the technique to answer our research question. This protocol received an ethical certificate from our institution's ethics committee. In this protocol, we use physiological devices18, mounted into a 3D-printed casing. We will refer to the device as the EDA boxes (boxes used to record the EDA of the participant), the light box (the box with a digital light), and the sync box (box that sends signals to the EDA boxes and the light boxes to synchronize data). The synchronization software enabling the wireless synchronisation protocol for the acquisition of multimodal user data17 was embedded onto the boxes.
The following protocol was approved by HEC Montréal's ethics committee prior to the beginning of the data collection.
1. Participant screening for the experiment
2. Conditions and experimental design
3. Preparation
NOTE: These materials are needed to perform the protocol: EDA box, the box used to record the EDA of the participant; light box, the box containing lighted digital numbers; and sync box, the box that sends signals to the EDA box and the light boxes to synchronize data. Two armbands, EDA electrodes, EDA sensors, medical tape, and antiseptic wipes are also needed.
4. Welcoming participants
5. Installation of the physiological device
6. Record baseline
7. Start the experiment
8. Start the game
9. Removal of physiological devices
10. Debrief the participants
11. Cleaning up materials
12. Physiological data management
13. Analyze the data
This section describes the representative results of this study. We recruited participants using social media and our institution's panel of participants. Of the 78 participants, 40 were women. The mean age was 22 years old. None of the participants had previously played the game. Other exclusion criteria can be found in step 1 of the protocol.
The descriptive statistics, which can be seen in Table 1, contain the mean per condition, for each measure. The mean of the arousal dimension of the Self-Assessment Manikin (SAM) is reported in the second row of the table. The SAM Scale was administered using a visual 9-point Likert scale ranging from calm to excited8 (see Supplementary File). Results show that the participants were more excited with the smartphone. The third row shows the difference between the mean of the standardized EDA for each condition, again showing that it was higher in the smartphone condition. The fourth row reports the means for each condition in the User Engagement Questionnaire Short Form (UES-SF), a 5-point Likert scale ranging from Strongly agree to Strongly disagree was used22. Again, results demonstrate that perceived engagement was higher in the smartphone condition. The p-values are reported for each measure, confirming their statistical significance. Employing the Baron & Kenny procedure, we were able to identify the mediating role of arousal in the relationship between interactivity and spectators' engagement23. Self-perceived arousal and self-perceived engagement had 78 participants and physiological arousal had 12 participants. The numbers are lower than what we recruited because we had to discard four EDA participants and two SAM Scale and UES-SF participants due to data loss.
These results show that this data collection and analysis method provides the necessary data to compare the two conditions of interactivity. As suggested by player experience literature3, combining lived and perceived arousal measures provide a more robust assessment. Moreover, this method allows for an ecologically valid measurement of both physiological and self-reported arousals, as the wireless EDA devices permitted a live recording during uninterrupted gameplay. Further, the self-reported arousal questionnaires were completed in between each game, directly on spectators' smartphones, which were already used to play the game. This allowed the participants to stay in the flow of the game.
Figure 1: Visual representation of the game. This figure shows the playground with one player on each side and six spectators watching from the side of the playground. All the participants are wearing a jersey with a number on it. Please click here to view a larger version of this figure.
Figure 2: Visual representation of the syncing devices. This figure shows the devices used to sync the EDA data. There is the sync box on the left and the light box14 showing a number at the right. Please click here to view a larger version of this figure.
Figure 3: Visual representation of the camera and light box. This figure shows a light box being positioned in front of a camera. The camera is on a tripod and the light box14 is on a mechanical arm that is mounted on the tripod. Please click here to view a larger version of this figure.
Figure 4: Relationships between variables. This schema represents the mediating role of arousal in the relationship between interactivity and spectators' engagement. Please click here to view a larger version of this figure.
With smartphone | Without smartphone | P-value | |
Self-perceived arousal | 5.54 | 4.64 | < .001 |
Physiological arousal (EDA) | 0.0295 | -0.1262 | < .001 |
Self-perceived engagement | 3.49 | 3.31 | < .001 |
Table 1: Descriptive statistics per group. The numbers represent the means of the total values of each measurement tool per condition of interactivity. The p-values are shown in the P-value column. P-values were measured using a linear regression with random intercept with a two-tailed level of significance.
Supplementary File 1: SAM scale Please click here to download this File.
Please note that the steps were performed in the studio of the creators of the game but could be replicated in a laboratory setting or another environment that has enough space to fit the game. It is important to note that the sync box can only transmit a pulse to the lights and EDA boxes that are within 20 meters. Therefore, the game room or playing field must not be larger.
Existing laboratory methods have used software to simultaneously begin both the recording of the videogame screen and physiological measurement tools10. In the context of digital games that do not take place within a screen, this method is inadequate. This issue is bypassed by the synchronization method described in our protocol. No matter when the recordings begin, the data can be synced. Our work has demonstrated that the technique proposed by Courtemanche et al. can be applied to game research, specifically, in games that take place outside of the traditional console-based gaming17. With the combination of synchronized physiological and video data, as well as self-reported measures, we were able to compare the two conditions of interactivity and observe a difference in engagement.
For researchers who wish to use this protocol, there are some recommendations that are not to be missed. The method relies on technology requiring long lasting battery power. All the material should be fully charged before the experiment to prevent data loss. The EDA equipment should always be tested prior to the experiment to make sure that it is fully charged, that the Bluetooth reception is working, and that the lights are flashing. Although the light boxes are very important for synchronization, if the light only sends one signal during the whole game it is possible to use the data. The events will then be calculated according to their camera time difference from that single signal. If one light is not sending any signal, it is possible to use the two others to calculate the events. If none of the lights are working, it is also possible to turn on the two EDA boxes and the sync box all at the same time and make it visible in the camera frame and rely on that for the synchronization of data, although this method will be less accurate.
EDA measurement can be affected by movement and sweat; this measurement could be compromised if the participants were to engage in intense physical activity. In the context of this game, what is important for spectators is simply to be able to walk around freely and use a smartphone. This level of physical activity was acceptable for our type of measurement. EDA sensors were placed on the non-dominant hand of the spectators, which allowed them to be comfortable using their smartphone with their other hand. Placing an armband on the hand and the arm of the participant is important as it helps ensure the sensor cable and the electrodes do not move. Particular attention must be paid to the movement artifacts during the data analysis process. Some data sets might need to be removed from the study.
It is also recommended to transfer the data after each session to avoid linking the data set to the wrong participant. This process also allows the verification of data recordings, as data cannot be visualized in real time. There should be three text files on each of the micro SD cards for each session per participant. The first file being the test (when the device was installed on the participant), the second file being the baseline, and the third file being the recording during the actual games.
The method presented in this work could be used by game designers who wish to understand the lived experience of the audience watching the game being played. As opposed to self-reports or interviews, physiological measures are objective and non-obtrusive to both the participants and the game24. Coupled with self-reported measures, they offer a more accurate way of assessing participants' emotional reactions24. A stronger understanding of the users will allow for a better design1. Due to its portable equipment, this method could be used outside of a laboratory setting. It could be recreated in the real context of the game, which is a public space in our case. This would further promote ecological validity. Other fields of research such as education and shopping, could also benefit from the portability aspect of this method and investigate its use. As Charland et al. state, engagement in learning is crucial5. This method could allow the assessment of the multiple dimensions of engagement in the real context of a class. Emotional responses have also been found to lead to important outcomes in the shopping environment25. This method could provide arousal assessment in the context of shopping malls. Further work would be needed to determine whether this methodology can be used in these other fields.
The authors have nothing to disclose.
We would like to thank MITACS in partnership with the company that created the game to have funded this research project.
BITalino (r)evolution Freestyle Kit (PLUX Wireless biosignals S.A.) | BITalino | 810121006 | |
Devices (1 syncbox, 3 light boxes, 2 EDA boxes) | Developed by Tech3Lab researchers1 | n/a | |
CubeHX2 | n/a | n/a | |
Charging station | Prime 60W 12A 6-Port Desktop Charger | RP-PC028 | |
6 USB3 wires for charging | Insignia 3m (10 ft.) Charge-and-Play USB A/ Micro USB Cable | NS-GPS4CC101-C2 | |
3D scanner | Velodyne LiDAR | VLP-16 | |
Projectors | Barco | F90-W13 | |
Jerseys* (fabric, tape, string) | Any | Any | |
2 low light cameras | Sony | A7S | |
2 tripods for the A7S | Manfrotto | MVK500190XV | |
2 light stands for the go pro and the syncbox | Impact | LS-8AI | |
1 plier for the light stand of the syncbox | Neewer | Super Clamp Plier Clip | |
1 magic arm for the light box of the go pro | Magic Arm | 143A | |
1 Go Pro | Go Pro | 5 | |
1 Microphone | Rode | VideoMic Rycote | |
2 armbands | Amyzor | Moisture Wicking Sweatband | |
*Make them yourself by taping the number on the fabric and perforating two holes to enter the string | |||
Sources: 1.Courtemanche, F. et al. Method of and System for Processing Signals Sensed From a User. US 15/552,788 (2018). 2. Léger, P.M., Courtemanche, F., Fredette, M., Sénécal, S. A cloud-based lab management and analytics software for triangulated human-centered research. In Lecture Notes in information Systems and Neuroscience. Edited by Thomas Fischer, 93-99, Springer. Cham (2019). |