BrainArt: a BCI-based Assessment of User’s Interests in a Museum Visit Fabio Abbattista Valeria Carofiglio Berardina De Carolis Department of Computer Science, Department of Computer Science, Department of Computer Science, University of Bari University of Bari University of Bari Bari, Italy Bari, Italy Bari, Italy fabio.abbattista@uniba.it valeria.carofiglio@uniba.it berardina.decarolis@uniba.it ABSTRACT into account that our brain processes constantly information and In the near future our brain will be connected to many applica- sensory inputs that pervade our daily life, it is easy to imagine ap- tions. Recently research has concentrated on using the Brain Com- plications that consider the impact of media (images, music, video, puter Interface (BCI) passively to recognize particular users’ mental movies, etc.) upon the brain. In case of a museum visit, the number states. In this paper, we explore the possibility to harness electroen- of items that users may look at is huge. In this case, personalized cephalograph (EEG) signals captured by off-the-shelf EEG low-cost suggestions may be used to tailor the visit to users’ interests and headsets to understand if an exhibition piece is of interest for a preferences. In recent years, the maturity of methods for the unob- visitor. This information can be used to enrich the user profile and trusive acquisition of implicit feedback [16] has grown to a level consequently to suggest artworks to see during the visit according that allows its incorporation in personalized systems. To this aim, to a recommendation strategy. The results of the exploratory study research has investigated the use of physiological signals to detect show the feasibility of the proposed approach and recognize users’ interest and engagement. Devices actually used to get this kind of feedback are mainly heartbeat monitors, CCS CONCEPTS galvanic skin response sensors and headsets to capture electroen- cephalogram (EEG) signals. In this paper we investigated on the • Human-centered computing → User models; use of a EEG low- cost commercial headset (MindWave - Neurosky) to capture and recognize the user interest in a artwork by detecting KEYWORDS his engagement level during the visualization of a piece of art. The BCI, Engagement, Museum Visit idea is to apply real-time brainwave signal detection techniques to ACM Reference Format: get a feedback about which pieces of the exhibition are interesting Fabio Abbattista, Valeria Carofiglio, and Berardina De Carolis. 2018. BrainArt: for the user while he is looking at that item. To achieve our goal we a BCI-based Assessment of User’s Interests in a Museum Visit. In Proceed- developed a function to detect visual engagement and then, to test ings of 2nd Workshop on Advanced Visual Interfaces for Cultural Heritage the feasibility of the approach, we performed a preliminary con- (AVI-CH 2018). Vol. 2091. CEUR-WS.org, Article 1. http://ceur-ws.org/Vol- trolled experiment aimed at detecting interest of museum visitors 2091/paper1.pdf, 4 pages. in a item and relating it to the level of visual engagement. Data collected in this experiment allowed learning a model for 1 INTRODUCTION recognizing in real-time user’s interest and use this information to Human–computer interaction based on physiological signals is enrich the user profile and provide recommendations accordingly. expected to be the next breakthrough in the field of multimedia The paper, after a brief section explaining the motivation for systems, especially as far as affective computing is concerned. In pursuing this approach, illustrates how visual engagement is calcu- this view, research presented in this study aims at developing a lated. Then the results of the study are presented. Conclusions and Brain-Computer Interface (BCI) to understand which exhibition future work directions are discussed in the last section. piece the user is interested in during a virtual/real museum visit and use this information to personalize the visit using an appropriate 2 MOTIVATIONS AND BACKGROUND recommendation strategy. Usually electroencephalography (EEG) devices and BCI provide a Many authors have investigated the use of physiological signals to way to measure brain activity and establish a direct communication detect and recognize users’ characteristics during the interaction between brain and computing systems. Useful applications of EEG [15]. Devices actually used to get bio and neuro-feedback have have been developed mainly in the field of assistive technologies, gained popularity especially in the context of videogames. Due helping disabled users to control external devices [9, 12]. However, to their ability to capture the engagement of a user beyond his with the advent of inexpensive and commercial EEG headsets, ap- conscious and controllable behaviors and in a transparent manner, plications in new domains are being proposed (e.g., for enhancing EEG devices are being used in HCI context [18]. Since non-invasive the user experience during artistic performances [21], for monitor- commercial electroencephalography (EEG) devices have recently ing attention levels during learning tasks [2], and so on). Taking become more available on the market it is feasible to think about their use in domains such us music listening, video watching, etc. EEG devices measure brain signals by placing electrodes on AVI-CH 2018, May 29, 2018, Castiglione della Pescaia, Italy certain locations on the scalp that measure changes in electrical © 2018 Copyright held by the owner/author(s). potential as neurons in the brain’s cerebral cortex are fired [13]. 1 AVI-CH 2018, May 29, 2018, Castiglione della Pescaia, Italy Fabio Abbattista, Valeria Carofiglio, and Berardina De Carolis The collected signals are divided into five different frequency bands that have been proven to provide insight into a person’s cognitive states such as attention/engagement and relaxation [17]. From the interaction viewpoint, BCI systems can be used in an active way, by allowing users to control a system by a conscious mental activity, and in a passive one, by monitoring the user brain activity to recognize mental states that are used as an input to the application [18] or to understand the user’s mental state as a feedback to the received stimulus. In this case the interpretation of user’s mental state could be used as a source of control to the automatic system adaptation [6]. This is the type of approach needed in our system, the indicators Figure 1: Neurosky wireless EEG Mindwave device. of "engaging" and "interest" as implicit feedback for personalizing the museum visit. Since in the last few years museums direct their efforts to provide personalized services both though their websites and on site offering personalized guide and descriptions of items, The headset is equipped with a single-channel EEG sensor and an this information about the user can be used to build a user profile electrode that rests on the forehead on the FP1 position according to and then to provide recommendations [10]. An increasing number the international 10-20 system and a second electrode that touches of museums use personalized museum guides to enhance visitors’ the ear. This sensor is used as ground to filter out the electrical experiences, attract new visitors, and satisfy the needs of a diverse noise. Sensors are capable of detecting raw EEG signals, frequency audience [11, 19]. Ardissono et al. [4] provide a detailed survey of different brainwaves: Delta (0-3 Hz), Theta (4-7 Hz), Alpha (8- of the field of personalized applications in cultural heritage. In 12 Hz), Beta (12-30 Hz) and Gamma (30-100 Hz), and two mental our approach the BCI can monitor passively the user’s experience states (attention and meditation) that are calculated by proprietary during the museum visit in real time providing a feedback that can algorithms. Neurosky MindWave was chosen due to its affordability, be used to personalize the visiting experience. portability, wireless connection capability and the availability of This approach has been used successfully in several projects. an open source API (Application Programming Interface). Finally, In the FOCUS system BCI is used to monitor engagement while it offers unencrypted EEG signal. children are reading [7]. Andujar and Gilbert [3] proposed a proof We are aware that a major limitation in using this headset is of concept investigating the ability to retain more information by the accuracy of the EEG signal, because this headset has only one incrementing physiological engagement using the Emotiv EPOC. electrode. However, our challenge is to have as much information Recently, Yan et al. [22] show how the measurement and analysis of as possible, avoiding stressing the user in terms of the discomfort of audience engagement from EEG measurement level during a three- the device. The size and comfort of the device used may allow for a dimensional virtual theatre performance have positive impacts on real-time assessment of users preferences and then for a provision the user experience. Abdelrahman et al. [1] report their experience of fine-tuned suggestions and content during the visit. in using EEGfeedback for detecting visual engagement of museum visitors using Emotiv EPOC. Results of these research works are promising and, even if the 3.1 Visual Engagement Measurement experiments were performed on a small number of users, they Electroencephalography (EEG) is a method to measure the brain’s show the potentiality of the approach. Therefore we decided to electrical activity. Usually the EEG signals can be affected by noise investigate if the same type of information about user’s mental due to eye movements, muscle noise, heart signals, and so on. The state could be captured using a cheaper headset with only one dry BCI allows filtering the noise signal while preserving the essential electrode. EEG signals. EEG frequencies have been extensively studied and can provide insight into user mood and emotions such as excite- ment, meditation, pleasure and frustration. EEG measures are also 3 THE PROPOSED APPROACH sensitive to cognitive states including engagement and attention. The visitor experience in a museum is mainly shaped by his behav- As far as engagement measurement is concerned, Pope et al. ior based on his interest and engagement in the exhibited items. [14] defined the following formula relying on three of the fre- The cognitive component of interest corresponds to the activation quency bands which correlate EEG signals with task engagement: of the pre-frontal cortex of the brain captured using EEG signals. Enдaдement = β/(α + θ ). We propose a museum experience that utilizes brain signals ac- The formula uses the Alpha (α) band (7-13 Hz) associated with quired by commercially available BCI systems to sense the museum relaxation, the Beta (β) band (13-30 Hz) associated with attentive- visitors’ engagement in exhibits and provide real- time feedback to ness and focus, and finally the Theta (θ ) band (4-7 Hz) associated the visitor with personalized recommendations. with dreaminess and creativity. The recent availability of low-cost commercial and comfortable Berka et al. [5] has shown that the engagement index reflected a EEG headsets makes the use of this technology affordable for a person’s process of visual scanning and attention. This formula has museum that can then serve a large number of users. In this work, been used successfully in several projects with encouraging results Neurosky [8] wireless EEG Mindwave device is used (Figure 1). [1, 3, 17]. 2 A BCI-based Assessment of User’s Interests in a Museum Visit AVI-CH 2018, May 29, 2018, Castiglione della Pescaia, Italy 4 AN EXPLORATORY STUDY In the following sections, we discuss our experimental setup, data collection and analysis and, at the end, our findings. 4.1 Participants and Methodology Twenty-four participants took part in the study aged from 16 to 60 (mean age of 26.9 with a standard deviation of 10.75). Sixteen of them were male and eight were female. Twenty participants were students and four were part of the teaching staff. According to the purpose of this study we selected 20 artworks Figure 2: An example of interaction sequence during the ex- from wikiart.org. The selection was made according to the five periment. main styles present in wikiart classification: Medieval Art, Re- naissance Art, Post Renaissance Art, Modern Art, Contem- porary Art. For each style, we selected artworks of two different a classification model. To this aim we used the WEKA platform genres: painting and sculpture. [20]. According to research on the topic we applied the SVM al- Before starting the experiment, participants were given an overview gorithm and, in particular, we used the SMO (Sequential Minimal regarding the EEG technology, experiment, and the type of data Optimization) algorithm that handles multiclass data by combining collected. Consent was signed by all of the subjects. Participants binary SMOs. The three classes of interest were NI= Not Interesting, were trained on how to use the headset and the application. Before N=Neutral, and I=Interesting. the experiment they were asked to wait few minutes to stabilize Results, calculated using 10-fold cross-validation, show an aver- EEG signals. The total time of the experiment was approximately 5 age accuracy on three classes of 0.75 and a average F1-measure of minutes for most of the participants. After completing the experi- 0.672. Analyzing the classification results in more details by looking ment, participants were asked to answer a questionnaire about their at the confusion matrix (see Table 1), we noticed that the majority demographics, health status and other questions to rate the device’s of instances of class N, corresponding to a neutral interest, were comfort level. The questionnaires showed that all of the subjects misclassified. This result is encouraging and, even if it does not pro- did not suffer from any health issues prior to the experiments. The vide a way in detecting nuances in the level of interest of the user, experiment was conducted in a room with controlled lighting in a it is able to discriminate between interesting and not interesting research lab in our Department. Both the experimental tasks and items. the EEG recording were controlled with the same computer. Table 1: Confusion Matrix 4.2 Data Acquisition NI N I In order to acquire data to learn a model that can be used to recog- 198 95 4 NI nize the user’s interest, we implemented an interface to randomly 95 9 36 N show the selected artworks to the user. 10 0 228 I The adopted protocol is the following (Figure 2). At the beginning of the interaction the user is asked to relax for 10 seconds. The data Supported by this result we studied the feasibility of using such in recorded in this time represents the baseline for that user. At the real-time by predicting user’s interest while looking at an exhibition end of this relaxation period, the artwork image, selected randomly, piece. To this aim we conducted a very simple experiment. We is shown to the user for 10 seconds. During this time, the brain selected 20 new items from wikiart.org equally distributed along signals are recorded and immediately after an evaluation screen the 5 styles used for the first experiment. is shown to the user. Through this screen, the user expresses his We asked to 10 participants, aged between 19 and 52 y.o, (avg=25.3, judgment in terms of "I’m interested" (I), "I’m not interested" (NI) std.dev=9.3) to perform a task similar to the one of the first exper- or "Neutral" (N). In order to relax the mind and move on to the next iment. Each participant had to wear the headset and look at 2 artwork, a neutral screen is shown again for 10 seconds. randomly selected artworks according to the protocol described Band power data is used to calculate visual engagement. In par- previously. This time, the interest or not towards the artwork was ticular, we use Pope’s formula to calculate a vector of engagement indicated by the system according to the result of the classification values both for the initial relax time (EngRelax) and for each artwork of the VEI done using the learned model. Each participant could visualization time (EngImage). Starting from these data we calculate agree or not with the system by changing the predicted interest. the Euclidean distance between the so acquired two vectors. This Hit Ratio is a way of calculating how many "hits" a user has in a distance represents the Visual Engagement Index (VEI) and it is list of recommended items. A "hit" could be defined as something stored in a log file together with the evaluation explicitly expressed that the user has clicked on, purchased, or saved/favourite (depend- by the user. A total of 580 instances were collected. ing on the context). In this case we consider a "hit" the agreement between the system prediction and the explicit user evaluation. If 4.3 Implicit Feedback Recognition we consider this as a measure of success of the classifier then the To implement a process able to use EEG signals as implicit feed- proposed approach showed to be effective since in 70% of cases the back, we used the data collected during the experiment to learn user agreed with the system prediction. 3 AVI-CH 2018, May 29, 2018, Castiglione della Pescaia, Italy Fabio Abbattista, Valeria Carofiglio, and Berardina De Carolis 5 CONCLUSION AND FUTURE WORK [6] Laurent George and Anatole Lécuyer. 2014. Passive Brain–Computer Interfaces. 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