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. 2024 May 17;19(5):e0303553. doi: 10.1371/journal.pone.0303553

Exploring empathic engagement in immersive media: An EEG study on mu rhythm suppression in VR

Jong-Hyun Lee 1, Sung Eun Lee 2, Young-Sung Kwon 3,*
Editor: Umer Asgher4
PMCID: PMC11101072  PMID: 38758939

Abstract

This study investigates the influence of immersive media, particularly Virtual Reality (VR), on empathic responses, in comparison to traditional television (TV), using electroencephalography (EEG). We employed mu rhythm suppression as a measurable neural marker to gauge empathic engagement, as its increase generally signifies heightened empathic responses. Our findings exhibit a greater mu rhythm suppression in VR conditions compared to TV conditions, suggesting a potential enhancement in empathic responses with VR. Furthermore, our results revealed that the strength of empathic responses was not confined to specific actions depicted in the video clips, underscoring the possibility of broader implications. This research contributes to the ongoing discourse on the effects of different media environments on empathic engagement, particularly emphasizing the unique role of immersive technologies such as VR. It invites further investigation into how such technologies can shape and potentially enhance the empathic experience.

Introduction

Empathy, one of key elements in deepening audience engagement, plays a significant role in enhancing the overall media consumption experience [1, 2]. It is defined as the ability to understand and share the feelings of others, leading audiences to emotionally or cognitively connect with characters by experiencing their joy, sorrow, and excitement, or by understanding their thoughts, motivations, and decisions [3, 4]. Such empathic connections with the characters can promote emotional investment and foster a more profound comprehension of the characters’ viewpoints, deepening audiences’ engagement with the narrative [17]. This engagement through empathy or empathic engagement might result in an enhanced media experience, blurring the lines between the viewer and the character, thus enriching the audience’s experience and expanding their appreciation for the diverse perspectives and experiences presented in the media.

Empathy has been extensively studied in relation to immersion, as immersive experiences have been shown to have a significant impact on eliciting empathy [819]. Immersion deeply captivates the audience, drawing them into a lifelike and compelling experience. This intense captivation, by making the story world more tangible and relatable, fosters a stronger empathetic connection with the characters and their journeys [20]. For instance, in cinema, the use of surround sound, large screens, and 3D technology can envelop viewers in the movie’s audio landscape and make visual elements more lifelike, which helps viewers to feel physically closer to the action. This allows viewers to feel more involved in the narrative, which in turn fosters empathic engagement [21]. Similarly, in literature, well-crafted descriptive language and engaging narrative techniques can transport readers into the story world, evoking strong empathic responses towards the characters and their experiences [22]. This suggests the degree of immersion may play a critical role in enhancing empathic responses in media experiences, making it an essential factor to consider when exploring the potential of different media formats to elicit empathy.

VR technology is becoming increasingly recognized as a device specialized for creating such immersive experiences. It generates a deep sense of presence and immersion by visually isolating users from their real-world environments [23], and enhancing the sensation of being present in a virtual space [24]. As an immersive device, VR introduces unique possibilities for media consumption [25], integrating these immersive experiences into various aspects of media, from video games to cinema to sports and even to rehabilitation [26].

This immersive quality of VR distinguishes it from traditional forms of media such as TV, potentially enabling a deeper, more nuanced empathic experience for audiences. In fact, building on its immersive qualities, VR has even been described as the ‘ultimate empathy machine’ [27]. The immersive nature of VR allows users to not only observe but also virtually embody the experiences and perspectives of others, facilitating a deeper understanding of their emotions and motivations. For instance, the VR film Clouds Over Sidra [28], which follows the life of a Syrian girl in a refugee camp, has been praised for its capacity to evoke empathy and understanding for the plight of refugees, without using special dramatic techniques [20].

However, empirical evidence supporting the effectiveness of VR in inducing empathy is still accumulating, and some researchers have reported mixed results [9, 12, 13, 15, 17, 19, 2931]. For instance, the extent to which VR elicits empathetic experiences compared to traditional media may vary, depending on factors such as users’ individual characteristics, their viewing perspective, and the specific task at hand [13, 17, 29]. Furthermore, neurophysiological evidence, such as EEG or fMRI data, remains scarce in this domain [32, 33], leaving a critical gap in our understanding of the underlying neural mechanisms involved in VR-induced empathic experiences. Consequently, further research is needed to better comprehend the true potential of VR as an empathy-enhancing medium and validate its claim as the ‘ultimate empathy machine’.

From a neurobiological perspective, empathy is often closely tied to the activation of the mirror neuron system. This intriguing neural network, initially identified in primates [34] and subsequently demonstrated in humans [35], is thought to be central to the capacity of experiencing empathy [36, 37]. The foundational principle behind this association is that mirror neurons are activated not just when an individual performs an action but also when they observe the same action being carried out by another [37, 38]. For instance, when participants observed simple hand movements, such as grasping, the same brain areas were activated as when they performed these movements themselves [37]. This dual activation creates a form of neural mirroring or resonance, which essentially allows our brains to mimic or replicate the observed action in internal neural systems, providing a potential neurological basis for the ability to understand and share the emotions and experiences of others, a fundamental aspect of empathy [37, 39, 40]. This distinctive feature of mirror neurons, hence, establishes the fundamental connection between the neurons and the capacity for empathy.

One of the most common neural correlates associated with the activation of the mirror neuron system is the suppression of the mu rhythm, a unique EEG pattern typically observed over the sensorimotor cortex [41]. The mu rhythm is noted to be suppressed, or ‘desynchronised’, during both action execution and action observation, mirroring the behaviour of the mirror neurons themselves [41, 42]. Thus, the suppression of the mu rhythm is an indirect measure of mirror neuron activity and, by extension, a quantifiable indicator of empathic responses [43, 44]. Research has indicated the magnitude of mu suppression during action observation may be reflective of the observer’s empathic engagement [4446]. For example, Perry et al. [46] found a correlation between the degree of mu suppression and the extent of empathy an observer feels for the person performing the action. Woodruff et al. [44] demonstrated individuals who exhibited stronger mu suppression also reported higher levels of empathy. These studies suggest mu rhythm suppression serves not only as a neural marker of mirror neuron system activity but also as a potential measure of empathic engagement.

Building on this background, in the present study, we aim to acquire a deeper understanding of how the immersive nature of VR can influence empathic responses in contrast to traditional TV, utilising EEG methodologies. The central inquiry of this research asks whether the immersive characteristics of VR augment the empathic experience in comparison to TV. In an attempt to answer this, we measure the degree of mu rhythm suppression, an EEG pattern associated with empathy, because it provides a glimpse into the workings of the mirror neuron system. During the EEG experiment, participants will be presented with a series of short video clips that display human actions in both VR and TV settings, which allows for a direct comparison of empathic responses triggered by each medium. The EEG activity of participants will be recorded during viewing to quantify the degree of mu rhythm suppression, thereby providing empirical evidence to assess the magnitude of empathic responses. This study includes two types of actions of varying complexity: simple, such as object grasping, and complex, such as punching and kicking. Although object grasping is typically used in action observation studies [34, 4749], its simplicity might limit one’s ability to fully represent empathetic responses. Thus, in this study, by probing the impact of action complexity on these responses, we attempt to indirectly assess the representativeness of this simple task. If the mu rhythm suppression is only triggered by actions in the simple conditions, this could suggest these reactions are specific to certain actions, which may limit our understanding of empathetic responses in more intricate narrative scenarios. Otherwise, the findings might suggest a potential applicability of the study’s results beyond the specific experimental items. The guiding hypothesis of this study is that the immersive VR environment will stimulate a stronger empathic response, indicated by a greater degree of mu rhythm suppression, compared to the TV setting. Furthermore, the complexity of actions depicted in the video clips might modulate mu rhythm suppression across VR and TV conditions, if the responses are limited to a certain type of actions.

Methods

Participants

We recruited a total of 30 participants (21 male and nine female university students, all of them were South Koreans) from the university’s website (Recruited from December 2022 to January 2023), with a mean age of 24.10 years (SD = 2.86). They were all right-handed, with normal or corrected-to-normal vision, and had some experience with VR in the past Prior to the experiment, we obtained written informed consent from each participant. We conducted the experiment in accordance with the guidelines approved by university hospital Institutional Review Board (IRB Approval number: 2-1040709-AB-N-01-202202-HR-016-04). Data (including EEG) are available from the corresponding author and University hospital IRB upon request.

Materials

The experimental stimuli comprised 60 short video clips, which were used identically in both media Each was shot with the Insta EVO 360 and then edited using Adobe Premiere Pro. Actors who appeared in the stimulus were recruited from aspiring actors at the university. The stimuli were classified into two categories based on the complexity of the depicted actions: simple and complex. Simple actions encompassed the grasping of an object such as a bottle, cup, or ball, with two variations: either halting the movement postgrasp (no withdrawal) or grasping and subsequently moving the object out of the screen’s frame (withdrawal). This grasping movement is a basic action that has been widely employed in several earlier studies [34, 4749]. Complex actions included a range of activities performed by an actor, such as punching and kicking. These actions are distinct from simple actions in that they encompass movements of the entire body rather than being confined to a right arm and have two or more interconnected motions. They were adapted from the previous studies investigating how the mirror neuron system is modulated based on the level of complexity of actions [5056]. In the videos, actors were shown both in full and partially, depending on the action being performed. For simpler actions, a closer, more focused shot was used. For complex actions involving whole-body movement, a wider shot was employed to capture the entire range of motion. Each video clip had a duration of 5 s, preceded by a 5-s black screen, thus totalling a 10-s duration per trial. Using a Latin-square design, we presented these materials in a random and counter-balanced manner. To account for potential order effects, we randomly assigned participants into two groups: one group first experienced the TV condition followed by the VR condition, whereas the other group underwent the conditions in reverse order. This design ensured a balanced representation of the TV and VR conditions across the participant pool.

Procedure

Upon arrival at the laboratory, we provided the participants with instructions and a consent form. After agreeing to participate, they were seated in a noise-attenuated shield room. After agreeing to participate, they were seated in a noise-attenuated shield room. They were then instructed to attentively observe the brief video segments, focusing on the various movements displayed. While they were watching the clips, we collected their EEG responses. Each experimental session, whether it was the TV or VR condition, lasted approximately 10 min. After completing one condition, we gave the participants a break before proceeding to the next condition while the video device was switched. The total duration of the experiment, inclusive of preparation time and breaks, ranged from 30–40 min. Participants were compensated with 30,000 KRW (equivalent to approximately 24 USD) for their participation.

Apparatus

For the TV condition, participants viewed the clips from a distance of 60 cm on a 24-in. monitor. In the VR condition, participants watched the video clips using an Oculus Rift S VR headset. The position of the headset was adjusted as needed to ensure participant comfort. We used virtual desktop applications (Virtual Space) to execute the VR condition and played the clips using a Python script.

EEG recording

EEG data were recorded using a 16-channel actiCAP Xpress V-amp EEG recorder (Brain Products). The data were digitized at a sampling rate of 500 Hz. Given that the actiCAP Xpress system allows for high impedance, the stability of the recording quality was visually assessed after achieving a minimum level of impedance. The dry electrode system, by means of this recording procedure, can reliably yield EEG spectra and ERP components comparable to those obtained from traditional electrode types [57]. Electrodes were placed according to the international 10–20 system, with the reference electrode positioned at the right earlobe and the ground electrode at the left earlobe. The EEG data were filtered online using a low cut-off of 0.1 Hz.

To accommodate both the VR and EEG devices, participants were first fitted with the EEG device and the signal quality was stabilized. Subsequently, the VR device was placed on the participant. Since the VR headset was designed without any attachments above the upper part of the head (dorsal area), it is possible to ensure minimal overlap with the EEG device. Once the VR and EEG devices were in place, the signal quality was checked again to confirm stability.

EEG preprocessing

All pre-processing of the raw EEG signals was conducted using the MNE-python package [58]. The raw EEG signals were first notch-filtered at 60 Hz and band-pass filtered within a frequency range of 1 to 40 Hz using a one-pass, zero-phase, non-causal FIR filter (Hamming window method, -6 dB cutoff frequencies: 0.50 Hz and 45.00 Hz). This initial step served to minimize noise and to focus on the most pertinent frequency range for the EEG signals. Following the filtering stage, ocular artifacts were corrected through an Independent Component Analysis (ICA) using the "picard" algorithm [59]. After the ICA ocular correction, the data were segmented into epochs spanning from 1 second before stimulus onset to 5 seconds after. The baseline was defined as the interval from -1 to 0 second relative to stimulus onset. The Python package ’autoreject’ [60] was used for artifact rejection, which provides a global rejection threshold and interpolates bad sensors for each epoch. The total data loss as a result of this artifact rejection process amounted to 6.47% (5.22% for TV, 7.72% for VR). After the artifact rejection, the data from two participants were excluded from further analysis because more than 30% of their trials in one of the two media conditions were rejected due to artifacts, in order to ensure a high-quality dataset for subsequent analysis. As a result, the final analysis included data from 28 participants.

Time-frequency analysis was conducted using a Morlet wavelet transform, set to seven cycles, with the frequency of interest ranging from 4 Hz to 30 Hz at 1 Hz intervals. The analysis focused on electrodes C3 and C4, which are commonly associated with the sensori-motor cortex and the mu rhythm suppression [56, 6163]. Power values were normalized to a ’percent’ rescale mode using a one-second pre-stimulus baseline period of black screen presentation. Upon obtaining the power for each epoch, these values were then averaged within each condition separately, yielding an average power value for each condition at each time-frequency point.

Statistical analysis

Statistical analyses were conducted using two primary methods: a repeated measures ANOVA and a non-parametric permutation F-test. The repeated measures ANOVA was performed using the rstatix library in R [64], which targeted the mu rhythm range (8 to 13 Hz) during a time window from stimulus onset to 5 seconds post-stimulus across two EEG channels, C3 and C4. The main effects of media (VR vs. TV) and complexity (simple vs. complex) were examined, as well as their interaction. The assumption of sphericity was checked, and if violated, the Greenhouse-Geisser correction was applied. A Bonferroni correction was used to address multiple comparisons, setting the significance level at 0.025 (0.05 divided by the number of channels, which is 2). In the event of any significant interactions, post-hoc pairwise comparisons would have been conducted. For the non-parametric permutation F-test, a similar analysis was conducted using the MNE-Python package. As with the ANOVA, the analysis targeted the C3 and C4 channels, but examined a frequency range of 8 to 30 Hz at 1 Hz intervals within the same time window of 0 to 5 seconds post-stimulus onset. The permutation test was based on 1024 permutations, and clusters were defined as adjacent time-frequency points where the observed F-value exceeded the 95th percentile of the permutation distribution (p<0.05). The cluster-level test statistic was the sum of the F-values within each cluster. To correct for multiple comparisons (two channels), a cluster-level threshold of p<0.025 was used (Bonferroni correction), meaning that only clusters with a p-value less than 0.025 were considered statistically significant. Two separate tests were conducted: one comparing the two media conditions (VR vs. TV), and the other comparing the two complexity conditions (simple vs. complex).

Results

ANOVA

The repeated measures ANOVA revealed a significant main effect of media on both C3 and C4 channels, with no other significant main effects or interactions observed (C3: F(1,27) = 25.331, p <0.001, C4: F(1,27) = 22.515, p <0.001). In the VR conditions, a larger suppression of the mu rhythm was observed across both channels compared to the TV conditions (Figs 1 and 2).

Fig 1. Mu rhythm suppression (8 to 13 Hz) for each electrode (C3, C4) across all conditions (media x complexity).

Fig 1

Fig 2. Power spectrograms ranging from 4 to 30 Hz.

Fig 2

Areas of power decrease and increase are indicated by blue and red shading, respectively. The mu rhythm range is marked by a red dotted line.

Non-parametric permutation F-test

The non-parametric permutation F-test results were consistent with the ANOVA findings, as a significant cluster (p<0.001) emerged within the mu rhythm range (8 to 13 Hz) during the media analysis (VR vs TV). The VR condition exhibited a more pronounced suppression compared to TV (Fig 3). As for the complexity analysis (Simple vs Complex), no significant cluster was identified in the mu range, but a significant cluster (p<0.025) was found in the beta frequency range (15 to 25 Hz) from 3 to 4 seconds. In this cluster, the complex condition displayed higher beta suppression than the simple one (Fig 4).

Fig 3. Nonparametric permutation F-test results for media condition (VR vs. TV).

Fig 3

Shaded areas signify significant clusters, with blue indicating greater suppression in VR conditions and red indicating greater enhancement in VR conditions.

Fig 4. Nonparametric permutation F-test results for complexity condition (simple vs. complex).

Fig 4

Shaded areas signify significant clusters, with blue indicating greater suppression in complex conditions and red indicating greater enhancement in complex conditions.

Discussion

In this study, we sought to investigate the impact of immersive media, specifically VR, on empathic experiences in comparison to traditional TV, utilising EEG as a measure of mu rhythm suppression, a neural marker associated with empathy. The results revealed that, both in the ANOVA and the nonparametric permutation F-test, there was a greater suppression of the mu rhythm in the VR condition compared to the TV condition, over central electrodes, suggesting VR elicits a stronger empathic response. Moreover, there was no significant interaction observed between the media type and the complexity of actions depicted in the video clips in both analyses. Finally, the nonparametric permutation F-test indicated there existed a significant difference in beta power between the simple and complex conditions, albeit not in the mu rhythm range, with the complex condition showing higher beta suppression.

The observed difference in mu rhythm suppression between the VR and TV conditions in our study implies a distinct activation of the mirror neuron system, commonly associated with empathic responses. This aligns with previous studies whose authors reported a heightened emotional engagement when interacting with VR content, as gauged through self-report surveys [9, 13, 17, 29, 30] and behavioural indices [15, 19]. For instance, Barbot and Kaufman [9] discovered that participants’ empathy levels were significantly amplified by the immersion and presence experienced in diverse immersive VR scenarios, gauged through self-report surveys. Nelson et al. [15] noted an increase in pro-environmental actions such as donating to charity among participants after they engaged with a VR presentation highlighting underwater environmental threats. Nevertheless, despite the significance of these findings, it is worth noting they largely relied on self-report measures and behavioural indices. Although these methodologies offer valuable insights, they are fundamentally subjective and might not fully capture the intricacy of empathic responses. In contrast, our study, through the use of EEG, offers a more objective and direct insight into the neural mechanisms underpinning these empathic experiences in different media environments. EEG’s high temporal resolution enables us to observe immediate neural responses, which may be overlooked or misinterpreted by subjective behavioural measures. This approach offers a more nuanced understanding of empathic engagement dynamics and contributes to the existing body of research by connecting behavioural findings with their neurophysiological correlates in VR-induced empathy.

Furthermore, the results of this study were not confined to specific action types such as grasping, given the absence of an interaction between media type and action complexity. The short video clips utilised in this research depicted simple actions of object grasping, following conventional material used in mu rhythm suppression studies. However, the inherent simplicity of these actions might impose limitations on the interpretability of the outcomes because mu rhythm suppression may only be associated with certain types of actions. Particularly, such simple actions might not represent those that typically evoke empathetic responses in the media narratives under investigation. To address this limitation, in the current study, we incorporated actions of varied complexity, and the findings indicated the type of action exerted no influence on the outcomes because more complex actions also prompted mu rhythm suppression. We do recognise, however, that the complex actions incorporated in this study are not fully representative of the intricate action sequences often found in media narratives. The results of our study may not be directly applicable to scenarios of greater complexity, thus warranting further research into this matter. Nonetheless, we endeavoured to gauge the potential generalisability of this simple material and at least demonstrated that these responses are not limited to certain types of actions.

One might argue that there was no difference in mu rhythm suppression between simple and complex conditions merely because the level of complexity was not sufficiently different. The increased number of consecutive actions and the involvement of the entire body might not suffice to markedly increase the complexity of an action. Such an argument is, however, partially countered by the differences observed in the beta band. The results revealed an increased beta suppression in the complex conditions. Beta suppression, often observed concurrently with mu rhythm suppression, is known to be associated with motor execution or observation [51, 52, 6570]. One characteristic that sets beta rhythms apart from mu rhythms within the alpha frequency band is the beta rebound, or a transient increase in the power of the beta frequency band after a motor action is completed [67, 68, 7176], which could potentially account for the observed discrepancy in beta suppression. The brevity of the simple actions featured in our study may have resulted in an earlier completion of the actions, leading to an earlier rebound effect. Additionally, beta power is known to be influenced by certain motor parameters, such as the velocity and perspective of the action [5052, 70]. Given that the simple and complex actions differed in velocity and perspective, they might have contributed to the observed differences in beta suppression. However, considering that primary objective of this study was not to directly compare simple and complex actions, various factors potentially affecting beta suppression were not meticulously regulated. Consequently, it is not possible to fully account for the difference between simple and complex actions. Nonetheless, our findings do indicate the presence of differences between these two types of actions, suggesting that the findings of this study might permit a broader interpretive scope, particularly in relation to actions of greater complexity.

What specific aspects of VR media might have elicited greater empathetic responses compared to TV, as evidenced by our findings? This study operated under the hypothesis that the immersive nature of VR is responsible for these empathetic responses. The immersive quality of VR is a result of the interplay of multiple factors. These include the perceived control over the virtual environment afforded by VR’s interactivity, the realism derived from multi-sensory inputs such as haptic feedback, three-dimensional visuals, and spatial audio, as well as the perception of being in a new space that emerges when users are separated from the external environment [23, 24, 26, 77, 78]. Collectively, these factors contribute to the creation of a compelling and immersive virtual environment. Among these various factors, the aspect deemed to have notably influenced the outcomes of this research is the sense of immersion stemming from isolation from external surroundings. When a user is isolated from their physical environment, their attention becomes more focused on the virtual world. This isolation, typically achieved by using VR headsets that block out external sights and sounds, helps create a more convincing and enveloping experience. By minimizing distractions from the real world, VR can more effectively trick users into perceiving it is in a different environment, enhancing the overall sense of presence and immersion within the virtual space [23, 7780]. In this study, the videos presented through VR and TV were identical in terms of video quality, audio, three-dimensionality, controllability, and interactivity. Therefore, the most prominent difference in the immersive qualities of VR between the two conditions was that wearing VR equipment isolated the participants from their surrounding environment. While participants in the TV condition had to remain aware of their physical surroundings, those in the VR setup were isolated from the external experimental environment, enabling concentrated engagement with the video. This divergence may have heightened the immersive experience in the VR setting, potentially leading to increased empathetic responses.

Nevertheless, it is important to approach this interpretation with consideration for two aspects. Firstly, the role of isolation in enhancing empathetic responses is inferred from the conditions of our experiment rather than a direct investigation into the effects of separation from external environments. Our research primarily focused on comparing TV and VR, ensuring that all video elements, except the media devices, were uniformly controlled. Hence, observed differences between the conditions are likely attributable to inherent disparities in the media themselves. The blocking of external environments, a pronounced difference induced by the media choice, might be interpreted as a crucial factor. However, as the present study did not explicitly experiment with isolation per se, comprehensive exploration of isolation’s impact necessitates further research. For instance, a study comparing the isolating effect could involve a TV setting engineered to block external distractions, akin to VR equipment, allowing concentrated focus on the monitor. The second consideration is that mere sensory isolation from external environments does not guarantee detachment and immersion. The use of VR gear, while focusing the user’s attention within the virtual environment, does not preclude awareness of the external world. For instance, wearing VR in public spaces [81] or being aware of others’ presence in the same room [82], may provoke anxiety and disrupt the immersive experience. In this study, conducted in the relatively secure setting of an experimental booth, the participants were less likely to experience insecurity or a heightened awareness of the external world. Nevertheless, it is crucial to recognize that the immersion resulting from this isolation is not solely due to sensory blocking. If the existence of the outside world is clearly perceived despite being sensually isolated, it could rather impede the immersive process.

Our study provides neurophysiological evidence indicating that VR elicits stronger empathic responses compared to traditional TV in the context of our experiment, contributing to the ongoing discourse on the potential of VR as an empathy-enhancing medium. The results consistently demonstrated a more significant mu rhythm suppression in VR conditions as opposed to TV conditions. Notably, the suppression of the mu rhythm was not confined to simple action but also extended to complex actions, which suggests our observations may be applicable to actions of greater complexity. We propose that the immersive quality of VR, particularly its ability to isolate users from their external environment, can be interpreted as a critical factor distinguishing it from TV in enhancing empathy. However, these findings still necessitate further research. Future studies should aim to explore a wider range of actions, including more complex and nuanced actions, to better reflect the varied action sequences found in real-world media. Moreover, additional research is required to fully understand how isolation or other immersive characteristics contributes to the empathic experience in VR. Such research would contribute to a more comprehensive understanding of how different types of media, the actions depicted therein, and immersive qualities influence empathic responses. Additionally, exploring these dynamics in other immersive media, beyond VR, could provide further insight into the role of media immersion in empathic engagement. This could also help inform the development of more effective and engaging media content, whether for entertainment, educational, therapeutic, or other purposes. Last, future research should aim to explore these findings in more diverse populations, including varying age groups, cultural backgrounds, and socioeconomic statuses, to enhance the generalizability and understanding of our study’s implications across a wider array of demographic groups.

In concluding our discussion, we carefully highlight the contributions of our study from two crucial perspectives: First, our findings advance the field by elucidating the complex dynamics of empathy in VR environments. By demonstrating the neurophysiological underpinnings of empathy through Mu rhythm analysis, our study fills a crucial gap in understanding and substantiates VR’s efficacy as a potent medium for empathy enhancement. This contribution is pivotal, offering a scientifically grounded perspective on leveraging VR to foster deeper empathic engagement. Second, exploring the neurophysiological responses associated with media immersion opens new horizons for academic exploration, laying a solid foundation for future research to build upon. By identifying specific neural correlates of empathic engagement in VR, our work invites a multidisciplinary dialogue and encourages further investigations that could explore various dimensions of empathy in immersive media. Thus, our study not only enriches the existing discourse with insights and empirical evidence but also sets the stage for a continued and expanding exploration into the capacity of immersive technologies to shape human empathy, ensuring the conversation remains dynamic and progressively forward-looking.

Data Availability

Data(including EEG) are fully available without restriction from the corresponding author upon request. For the long term stability and availability of data, data are also available from the University hospital IRB(+82-51-200-6503/irb@dau.ac.kr/https://dms.donga.ac.kr/research2/index.do).

Funding Statement

This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government awarded to Y-SK [MSIT; No. NRF-2020R1G1A1101384] and the Ascending SNU Future Leader Fellowship through Seoul National University awarded to J-HL. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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Decision Letter 0

Umer Asgher

24 Oct 2023

PONE-D-23-28605Exploring Empathic Engagement in Immersive Media: An EEG study on Mu rhythm suppression in VRPLOS ONE

Dear Dr. Kwon,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process. Major revision is required as per the feedback and comments from the reviewers (feedback appended below).

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Reviewers' comments:

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Reviewer #1: Partly

Reviewer #2: Yes

Reviewer #3: Yes

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Reviewer #1: I Don't Know

Reviewer #2: Yes

Reviewer #3: Yes

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Reviewer #1: No

Reviewer #2: Yes

Reviewer #3: Yes

**********

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Reviewer #2: Yes

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5. Review Comments to the Author

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Reviewer #1: Dear Authors,

Thank you for providing me with this opportunity to review the manuscript titled ”Exploring Empathic Engagement in Immersive Media: An EEG study on Mu rhythm suppression in VR”. Hopefully this review statement helps in developing the manuscript further.

To begin with, the introduction could position the manuscript more explicitly vis-à-vis prior literature. For instance, why do we need to compare VR and TV? Furthermore, the argument “empathy…is a crucial element in media experiences” needs more flesh around the bones. How is it a crucial element? What do we know about it so far? In addition, “…for eliciting empathic responses…” (p. 1) would benefit from concrete examples.

In a way, it feels as if the manuscript jumps directly to the topic without properly paving the way. In other words, rushing to the topic results in the manuscript being inadequately positioned with regards to prior literature. As such, the introduction should provide a more nuanced and granulated image of the current body of knowledge.

Methodology: based on what criteria / prior research were the videos created? Also, were the actors shown in the videos? If so, were they shown in full or partially? Stills of the videos would be very helpful. Also, could you cite similar studies to strengthen the methodologocial choices? What does the simple / complex distinction tell us?

Furthermore, engagement towards what? Actor, object, action?

Were the VR and TV clips similar / identical?

Is it possible to share the material so others could replicate your study? Did the author team create the videos or someone else?

Methods section pp. 8-10 does not seem to have any references.

Point being, the methodology section needs to be stronger and more transparent. As it is now, challenging to see how insights were derived from the data.

Findings:

Is it possible to have a more nuanced treatment of the findings? For example, were there differences across the videos (not only simple – complex distinction)? As it is now, the findings feel very flat and after reading the manuscript I was hoping to learn more rather than “VR is superior to TV”; yes, I buy this, but how exactly could VR be more superior in this context? Under what conditions? Is VR always more superior?

Conversely: my co-author and I studied the use of VR in a public space (metro) and one of our findings was that people felt a bit insecure with a VR headset on. In other words, they weren’t always sure they were safe. While we didn’t compare VR with TV, one could say in public spaces VR might not be as efficient as TV because of the safety / security aspect. So, a more nuanced analysis of the findings would definitely make the paper stronger.

For instance, p. 15: “…a more nuanced understanding of empathic engagement dynamics…” – yes, this would be great, yet the manuscript does not address such dynamics at the moment. This would be a great vantage point for making contributions with this study to the current body of knowledge.

Is p. 16 necessary? How does it advance the contributions of the manuscript? Granted, I am definitely not an expert on beta suppression, but regardless this section feels a bit like a sidestep. Instead, I would focus more on the above rather than introducing new concepts.

p. 17 – “…VR may evoke stronger empathic responses” – this is super interesting and yet another potentially beneficial vantage point. How could others build on these insights?

Building on the above, and repeated below, it would be great to highlight this vantage point: “how could this paper open up rather than close down discussion?”. How might one build on this work? Instead of reporting findings, present them so that the manuscript explicitly encourages others to do more work in this domain. Here, a helpful vantage point could be this: what might be the three things the reader could take away from this manuscript?

Once again, thank you for the opportunity to review this manuscript. Hope this review statement helps in developing the manuscript further.

Minor comments:

- After revising the manuscript, the abstract could also be revised so it does not oversell the findings. There is no need for that. Instead, focus on the contributions and how these findings open up rather than close down discussion

- P. 3 – “Empathy, encompassing both…” sentence repeats what has been said above

- P. 3 – last paragraph is very interesting and promising

- P. 4 – “Immersion captivates…” – could be rephrased; how exactly does immersion lead to emotional connection?

- P. 4 – “For instance, in cinema…” – not sure the causality presented in this sentence is clear. Either tone down or explicitly explain the situation to the reader

- P. 4 – top paragraph – in general, the top part presents strong causalities that, in fact, are not necessary from the paper’s contributions’ point of view. Instead, provide a more nuanced treatment of the current body of knowledge so the paper’s contributions stand out on their own.

- P. 5 “ultimate empathy machine” – similarly, a very strong statement. No need to oversell the topic.

- P. 5 – Clouds Over Sidra – this is a good example, yes, but are there more examples?

- P. 5 middle paragraph is very nice as it has a nuanced and granular take on prior literature

- P. 6 – top paragraph – examples would make this paragraph more accessible

- P. 17 – “…superiority of VR…” – yet another strong statement

Reviewer #2: The manuscript is well-organized and clearly written, with a well-defined research question and hypothesis. The methods are rigorous and appropriate for addressing the research question, and the results are clearly presented and supported by the data. I particularly appreciate the thoroughness of the discussion section, which provides a comprehensive analysis of the findings and their implications.

Overall, I believe that the manuscript is a valuable contribution to the field, and I am confident that it will be well-received by the readership of PLOS ONE. I look forward to seeing it published.

Reviewer #3: A review of the manuscript titled "Exploring Empathic Engagement in Immersive Media: An EEG study on Mu rhythm suppression in VR."

The introduction effectively contextualizes the research, outlines the research questions, highlights the significance of the study, and provides a clear hypothesis. It also demonstrates a solid connection to existing literature and a comprehensive understanding of the topic, making it a well-structured and informative paper section.

The front matter provides a clear and informative background on immersive media technologies, especially virtual reality (VR), and their potential impact on empathy. It effectively sets the stage for the research study by outlining the significance of empathy in media experiences. The paper includes citations from prominent media studies and empathy scholars; therefore, the research is grounded in existing literature and theoretical frameworks.

The paper effectively highlights a research gap related to the effectiveness of VR in inducing empathy and the lack of neurophysiological evidence in this domain. It then articulates the central research questions. The discussion on the relationship between immersion and empathy is well-founded and coherent. It explains how immersion in various media forms can foster empathic engagement and sets the stage for the unique immersive qualities of VR.

The authors discuss the distinctive characteristics of VR, such as its capacity to create a sense of presence and interactivity, effectively underscores why VR is of particular interest in the study of empathy and cites previous research to support claims about VR's immersive qualities — adding credibility to the later discussion. The paper acknowledges the existence of mixed results in earlier research regarding VR's impact on empathy — demonstrating an awareness of the complexity of the topic and a willingness to critically assess the claims made about VR as the "ultimate empathy machine."

The introduction proposes the neurobiological basis of empathy and its connection to the mirror neuron system — adding depth to the discussion and positioning the research within the field of neuroscience. The explanation of the mu rhythm and its connection to empathic engagement is well-defined. It explains how EEG data can be used as an empirical measure of empathy, a vital aspect of the study's methodology.

The introduction concludes with a clear hypothesis that states the expected outcome of the study, which is that VR will lead to a more robust empathic response compared to TV and that the complexity of actions may modulate this response.

The Methods section outlines the comprehensive and well-structured research design, data collection, and analysis procedures. The section begins with a clear and concise description of the participants, including their demographics and the recruitment method. Including gender and age information and the number of participants is crucial for transparency. Mentioning that the experiment was conducted per the university's ethics guidelines reinforces the ethical considerations.

The description of the experimental stimuli is detailed, including information about the camera used and the source of the actors. Categorizing stimuli into simple and complex actions adds clarity to the design. However, providing information on the number of clips in each category would be beneficial to understanding the balance in stimuli representation.

The procedure section offers a step-by-step explanation of how the experiment was conducted. It covers participant instructions, EEG data collection, and the overall time frame of the investigation. The random assignment of participants to TV and VR conditions and the provision of breaks between states is essential for minimizing order effects and ensuring participant comfort. The compensation details are also evident.

The description of the equipment used for the TV and VR conditions is detailed and adequately explains how the VR headset and EEG devices were combined without interference — this is vital information for understanding how the experiment was conducted. The section clearly describes the EEG recording setup, including the type of EEG recorder, electrode placement, and electrode reference. The explanation of how the VR headset was combined with EEG devices is well-detailed and suggests care in the experimental setup.

The preprocessing steps are thoroughly explained, from filtering to artifact rejection. Including the Python packages and the description of the data loss due to artifact rejection adds transparency to the methodology. However, mentioning the specific criteria for data rejection might be helpful to address potential concerns about subjective judgments.

The description of the time-frequency analysis is concise and mentions the choice of electrodes, frequency range, and power normalization. These details provide insight into the analytical approach. The section explains the statistical methods employed, including repeated measures ANOVA and non-parametric permutation F-test. It mentions the handling of multiple comparisons and correction methods, enhancing the rigor of the analysis.

The Results section presents the findings, including the statistical tests performed and the graphical representations of the data. The area begins with the results of the repeated measures ANOVA, which is appropriate for testing main effects and interactions. The main impact of media on both C3 and C4 channels is significant, with p-values provided — this demonstrates that the media condition (VR vs. TV) has a notable impact on mu rhythm suppression in the specified EEG channels. The significance level is appropriately indicated (p < 0.001). The results effectively demonstrate that the results from the non-parametric permutation F-test are consistent with the ANOVA findings — this adds credibility to the results by showing consistency across two statistical methods. The report also notes the absence of significant clusters in the complexity analysis, which is essential information for the reader. It highlights that no significant differences in mu rhythm suppression were found between simple and complex conditions. The significance threshold (p<0.025) is clearly stated. The inclusion of figures (Figure 1, Figure 2, and Figure 3) helps visualize the results. Figure 1 provides a graphical representation of the mu rhythm suppression across conditions, assisting the readers to interpret the main effect of media and complexity. Figure 2 offers power spectrograms, which help understand changes in power across the frequency range. Figure 3 includes a clear and informative legend that explains the color coding used to indicate significant clusters. The distinction between blue and red shading for more significant suppression or enhancement is presented, making the results easier to interpret. Still, the color coding needs to be changed for color-blind accessibility.

The paper's Discussion section effectively addresses the findings and provides insightful interpretations and implications. The section provides a clear and comprehensive understanding of the study's results. It appropriately discusses the main conclusions of mu rhythm suppression in VR versus TV conditions. The discussion effectively links the results to previous immersive media, empathy, and mirror neuron system activation research. This connection to existing literature adds depth and context to the findings. The paper correctly highlights the advantages of using EEG to measure neural responses. The discussion points out the benefits of objective, neurophysiological measures in contrast to subjective self-report measures often used in previous studies. The section addresses the role of action complexity in the findings and raises valuable points about the limitations of using simple actions in the study. The discussion acknowledges the potential limitations and opens the door for future research.

The discussion of beta suppression and its potential implications for the observed differences between simple and complex conditions is well-presented. It appropriately suggests that future research should delve deeper into the influence of action complexity on neural responses. This section successfully summarizes the study's main contributions to the field, emphasizing the potential of VR as an empathy-enhancing medium. It highlights the consistent mu rhythm suppression observed in VR and the need for further research to explore different media types and actions.

The paper concludes with insightful suggestions for future research, including exploring action complexity, the role of media immersion in empathic engagement, and potential applications in various domains. The final section is well-structured and effectively interprets the results in the context of existing literature. It also identifies limitations and provides valuable directions for future research, making it a solid and informative part of the paper.

The paper demonstrates a clear and well-structured format, making it easy for readers to follow the research design, methods, findings, and interpretations. The article effectively integrates relevant literature into the introduction and discussion sections, enhancing the study's context and relevance. Using EEG as a neurophysiological measure is appropriate, and the paper provides a good rationale for this choice. It highlights the advantages of using objective criteria compared to subjective self-report measures. The report explores an exciting and relevant topic by investigating immersive media's impact on empathic experiences, particularly VR. This research area has practical applications and implications for various fields. The methods section is well-detailed, and using both ANOVA and non-parametric permutation F-tests provides robust statistical analysis. The paper addresses participant demographics, materials, apparatus, and data analysis factors. The "Discussion" section is a strength of the article. It effectively interprets the results, connects them to existing literature, acknowledges limitations, and suggests promising directions for future research.

While the paper demonstrates several strengths, some areas could be improved or have limitations.

• The sample size in the study is relatively small (30 participants), which may limit the generalizability of the findings. Increasing the sample size could strengthen the study's reliability and validity.

• The study mentions recruiting university students, which might introduce a potential bias in the sample's demographic characteristics. More information on participant demographics, such as age, background, and experience with VR, could be helpful.

• The paper does not mention diversity in the sample, which is a common concern in research. It's essential to consider the impact of gender, age, and cultural background on empathic responses.

• The paper acknowledges the limitation of using simple actions for the study. Exploring a broader range of activities, including those more typical of complex media narratives, would be valuable — for example, the 2021 paper Exploring Virtual Reality for Quality Immersive Empathy Building Experiences in Behaviour & Information Technology.

• The study's findings are based on specific experimental conditions, and the paper acknowledges that more research is needed. It's important to highlight that the results may not universally apply to all VR or media content.

• The study is conducted in a controlled laboratory setting, and the actions in the videos are artificial. It may not fully represent the complexity and emotional engagement of real-world media experiences.

• While the study looks at neural markers associated with empathy, it's essential to recognize that empathy is a complex psychological and neurobiological phenomenon. The paper acknowledges this but should emphasize the complexity of the topic further.

• The paper mentions obtaining informed consent and following ethical guidelines. Still, more information on the ethical aspects of the research, particularly in the context of using VR technology, would be beneficial.

• The paper's conclusion could be more concise and emphasize the essential findings and implications.

It's important to note that many of these concerns are typical of scientific research and should be considered opportunities for further investigation and improvement rather than significant flaws.

In summary, the paper demonstrates a robust research design, a clear presentation of results, and insightful interpretations. It effectively contributes to understanding the relationship between immersive media, empathy, and neural mechanisms. Overall, the paper appears to be of good quality and contributes meaningfully to its field of study.

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6. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: Yes: Miikka J. Lehtonen

Reviewer #2: Yes: Wahab Khan

Reviewer #3: Yes: Gareth W. Young

**********

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

PLoS One. 2024 May 17;19(5):e0303553. doi: 10.1371/journal.pone.0303553.r002

Author response to Decision Letter 0


23 Feb 2024

Dear reviewers,

We would like to thank you for the detailed and insightful comments. In response, we have made revisions that we feel much strengthened our manuscript. Please see detailed responses to your individual comments in the attached 'Response to Reviewers' file. We have so far tried our best to revise our manuscript and clarify important concerns that you raised. Please do not hesitate to let us know if you need more information or have other questions or concerns. Much gratitude again for your time and contribution to this work.

Respectfully yours,

Author

Attachment

Submitted filename: Response to Reviewers.docx

pone.0303553.s001.docx (35KB, docx)

Decision Letter 1

Umer Asgher

26 Mar 2024

PONE-D-23-28605R1Exploring Empathic Engagement in Immersive Media: An EEG study on Mu rhythm suppression in VRPLOS ONE

Dear Dr. Kwon,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process. Please submit your revised manuscript by May 10 2024 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

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We look forward to receiving your revised manuscript.

Kind regards,

Umer Asgher, PhD

Academic Editor

PLOS ONE

Journal Requirements:

Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: (No Response)

Reviewer #3: (No Response)

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2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #3: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #3: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #3: No

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5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #3: Yes

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6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: Dear Authors,

I was delighted to engage with this revised manuscript titled “Exploring Empathic Engagement in Immersive Media: An EEG study on Mu rhythm suppression in VR”. Most of the issues addressed by the reviewers have now been resolved, and many thanks for providing such detailed responses to the review statements.

At this point, there are only two minor issues and one tiny comment:

Introduction (minor issue): while this section has considerably improved, there is room for making it even stronger to help the readers engage with the manuscript more thoroughly. For instance, this is how the introduction’s structure could look like:

1. Engagement has been found to be an issue in immersive media

2. Empathy, amongst other factors such as immersion, plays a crucial role in evoking engagement

3. Yet, we do not know much about how, and through what mechanisms, VR evokes empathic engagement

4. Thus, more research is required to better understand how empathic engagement in VR differs from more traditional media

The above is just a suggestion, mind you. The rest of the manuscript is now very strong, and getting the introduction to the same level would be very critical at the moment. To be precise, I do not see this as a major undertaking; all the key ideas are there in the introduction, it just needs a stronger structure.

Methodology (tiny comment): Were the participants given USD 24 for their participation or X won equivalent to USD 24? (Also, “$24 USD” should be either $24 or USD 24) As said, tiny comment, but crucial in the sense of ensuring the manuscript does not contain any ambiguities. As a concrete suggestion, I would disclose how many won each participant received and in brackets how much it would be in USD. This, of course, assuming that the participants received won instead of USD. If they did receive USD, my apologies for the wrong assumption. In such case, please only consider the comment on the spelling format.

Contributions (minor issue): at the end of the discussion, I would highlight the contributions more explicitly from two perspectives: 1) how do the findings contribute to extant body of knowledge, and 2) how do the findings open up rather than close down conversation (i.e. future research avenues). Again, all the information is there, I would just make these two aspects very explicit to the reader so that the manuscript would receive the attention and engagement it deserves.

Once again, thank you for this review opportunity. Revisions have considerably strengthened the manuscript, nicely done.

Reviewer #3: The newest version of the paper "Exploring Empathic Engagement in Immersive Media: An EEG study on Mu rhythm suppression in VR" significantly clarifies how it contributes to understanding the neural mechanisms of empathic engagement in immersive media. Its methodological rigor, innovative approach, and insightful analysis are commendable. However, addressing the areas highlighted below for improvement could enhance the findings' robustness and impact, paving the way for further research in this intriguing field.

The paper employs an innovative EEG approach to measure mu rhythm suppression to indicate empathic engagement in immersive media — this provides a quantifiable measure of empathy, offering valuable insights into the neural underpinnings of empathic responses in VR and TV media environments. The results indicate a more significant mu rhythm suppression in VR than in TV, suggesting a more robust empathic response in immersive VR environments — this contributes to the growing literature on VR's potential as an empathy-enhancing medium.

The detailed and well-structured methodology section provides clear information on participant selection, materials, procedures, apparatus, EEG recording, and preprocessing. This thoroughness ensures reproducibility and enhances the study's credibility. While the study attempts to address the complexity of actions depicted in VR and TV media, it acknowledges that the complex actions used may not fully represent the range of actions in media narratives. Future studies could explore a more comprehensive array of complex actions to enhance understanding of empathic responses in varied contexts. The paper could further elaborate on the technical aspects of EEG data collection and analysis, including the choice of electrodes, the rationale behind the specific frequency ranges examined, and any potential limitations these choices entail.

The statistical analyses are robust, using repeated measures ANOVA and non-parametric permutation F-tests to examine the data. This dual approach strengthens the study's findings by addressing the potential methodological limitations of each statistical method. The discussion suggests that the isolation effect of VR (i.e., blocking out the external environment) may contribute to enhanced empathic responses. However, this is inferred rather than directly investigated. Future research examining the role of isolation in empathy could provide more definitive insights.

The discussion provides a thoughtful interpretation of the findings, linking them to existing research and theory. It also acknowledges the study's limitations and suggests avenues for future research, demonstrating the authors' critical engagement with their work. The paper could benefit from a broader discussion on the generalizability of its findings. For example, the sample size and demographics (e.g., all participants being university students) may limit the applicability of the results to broader populations.

While the paper posits that the immersive quality of VR is primarily responsible for enhanced empathic responses, it would be beneficial to consider and discuss alternative explanations or contributing factors more thoroughly. For instance, the role of narrative engagement, user interactivity, and the novelty of VR technology could also influence empathic responses.

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: Yes: Miikka J. Lehtonen

Reviewer #3: Yes: Gareth W. Young

**********

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

PLoS One. 2024 May 17;19(5):e0303553. doi: 10.1371/journal.pone.0303553.r004

Author response to Decision Letter 1


31 Mar 2024

Dear reviewers,

We want to thank you once again for the detailed and insightful comments. We have tried our best to revise our manuscript and clarify important concerns that you raised. Please see detailed responses to your individual comments on the 'Response to Reviewers (Minor Revision)' file. Again, we are grateful for your time and contribution to this work.

Sincerely,

Corresponding author

Attachment

Submitted filename: Response to Reviewers (Minor Revision).docx

pone.0303553.s002.docx (20.1KB, docx)

Decision Letter 2

Umer Asgher

29 Apr 2024

Exploring Empathic Engagement in Immersive Media: An EEG study on Mu rhythm suppression in VR

PONE-D-23-28605R2

Dear Dr. Kwon,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

An invoice will be generated when your article is formally accepted. Please note, if your institution has a publishing partnership with PLOS and your article meets the relevant criteria, all or part of your publication costs will be covered. Please make sure your user information is up-to-date by logging into Editorial Manager at Editorial Manager® and clicking the ‘Update My Information' link at the top of the page. If you have any questions relating to publication charges, please contact our Author Billing department directly at authorbilling@plos.org.

If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

Kind regards,

Umer Asgher, PhD

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: Dear Authors,

Thank you for diligently addressing the comments from both reviewers. The manuscript reads now very smoothly, and it is also nicely grounded in prior literature. More importantly, however, I am convinced that this paper will inspire readers to carry out further inquiries. Well done!

Thank you for such a pleasurable review process. Already now I have learned a lot from this manuscript. Also, thank you for very constructive and kind responses to reviewers’ comments. It has been a pleasure working with you on this paper.

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: Yes: Miikka J. Lehtonen

**********

Acceptance letter

Umer Asgher

7 May 2024

PONE-D-23-28605R2

PLOS ONE

Dear Dr. Kwon,

I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now being handed over to our production team.

At this stage, our production department will prepare your paper for publication. This includes ensuring the following:

* All references, tables, and figures are properly cited

* All relevant supporting information is included in the manuscript submission,

* There are no issues that prevent the paper from being properly typeset

If revisions are needed, the production department will contact you directly to resolve them. If no revisions are needed, you will receive an email when the publication date has been set. At this time, we do not offer pre-publication proofs to authors during production of the accepted work. Please keep in mind that we are working through a large volume of accepted articles, so please give us a few weeks to review your paper and let you know the next and final steps.

Lastly, if your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

If we can help with anything else, please email us at customercare@plos.org.

Thank you for submitting your work to PLOS ONE and supporting open access.

Kind regards,

PLOS ONE Editorial Office Staff

on behalf of

Dr. Umer Asgher

Academic Editor

PLOS ONE

Associated Data

    This section collects any data citations, data availability statements, or supplementary materials included in this article.

    Supplementary Materials

    Attachment

    Submitted filename: Response to Reviewers.docx

    pone.0303553.s001.docx (35KB, docx)
    Attachment

    Submitted filename: Response to Reviewers (Minor Revision).docx

    pone.0303553.s002.docx (20.1KB, docx)

    Data Availability Statement

    Data(including EEG) are fully available without restriction from the corresponding author upon request. For the long term stability and availability of data, data are also available from the University hospital IRB(+82-51-200-6503/irb@dau.ac.kr/https://dms.donga.ac.kr/research2/index.do).


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