Psychophysiological interaction offers the opportunity of delivering unique and innovative experiences that synergize with human physiological and psychological nature. Even though several publications have explored the use of psychophysiological interaction in video games in the past, there is still a set of challenges associated with its suitability for commercial entertainment games, and with the assessment of its relationship with the perceived player experience.

This dissertation explores psychophysiological interaction and its implementation within entertainment video games. It presents a review of multiple physiological methods, such as eye tracking, electrodermal activity, or electroencephalography, and discusses the possibilities and challenges that these methodologies offer for the design and implementation of natural user interaction techniques. The dissertation presents a set of user studies that evaluated the efficiency of psychophysiological interaction in desktop and virtual reality video games, and statistically assessed how the variations of player physiological data may relate to their respective changes in the perceived player experience. The dissertation also offers a set of ethical and methodological guidelines for the appropriate design of novel interaction techniques, and for the safe exposure of physiological sensors and virtual reality technologies to the general public.

The results obtained from this research show that the implementation of psychophysiological interaction in entertainment video games tends to positively affect player experience. However, this benefit comes as a tradeoff to player performance and their perceived sense of control. Additionally, the variations in electrodermal activity data, specifically in the skin conductance level, showed a tendency to correlate with negative player experience variables. Finally, psychophysiological interaction should be consistent with the natural behavior and reactions from players, and should be complementary to more traditional game interaction technologies.

Electrodermal activity is considered one of the more reliable methodologies to assess emotional arousal, and it has been adopted as an alternative method for the analysis of player experience in video game research. In this study, we present a quantitative evaluation of self-contained electrodermal measurements, focusing on the analysis of the tonic component and its potential relationship with player experience. The analysis presents a frequency-domain feature quantification of the tonic component, named gradual changes. With it, we evaluate how the variation of the tonic component correlates with the player experience valence, in a set virtual reality games. The analysis also offers an evaluation of the prediction capabilities of the gradual changes, to classify player experience, using a supervised learning approach. Our results support the idea that the tonic component correlates with player experience, statistically demonstrating that a higher number of gradual changes feature a directly proportional relationship with a negative valence in player experience. Despite this, the gradual changes featured a rather limited prediction capability upon player experience, motivating future work in this area.

Thanks to its effectiveness, electrodermal activity (EDA) has been previously included as an evaluation metric, within analyses of user experience. In this study, the phasic component of participants’ EDA data is examined in relation to their reported experiences when playing a set of virtual reality games, that featured the HTC Vive and Leap Motion controllers for input. Two models are used in the analysis of the phasic component: a deconvolution model and a convex optimization model. Despite having significant differences in their player experiences, results indicate that there are not many significant differences in the phasic component data. Even if some weak correlations were found, the majority of results show no linear correlations between the phasic component data and the reported experience variables. This shows that the phasic component of EDA data should be further investigated in conjunction with other psychophysiological signals because it has only recently demonstrated a weak link with player experience. © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG.

Electrodermal activity (EDA) is considered to be an effective metric for measuring changes in the arousal level of people. In this paper, the phasic component of EDA data from players is analyzed in relation to their reported experience from a standardized questionnaire, when interacting with a couple of virtual reality games that featured two different input devices: the HTC Vive and Leap Motion controllers. Initial results show that there are no significant differences in the phasic component data, despite having significant differences in their respective player experience. Furthermore, no linear correlations are found between the phasic component data and the evaluated experience variables, with the only exception of negative affect which features a weak positive correlation. In conclusion, the phasic component of EDA data has here shown a limited correlation with player experience and should be further explored in combination with other psychophysiological signals.

The area of biofeedback interaction has grown over recent years, thanks to the release of more affordable and reliable sensor technology, and the accessibility offered by modern game development tools. This article presents a systematic literature review focusing on how different biofeedback interaction methods have been used for entertainment purposes in video games, between 2008 and 2020. It divides previous contributions in terms of a proposed interaction classification criteria and five different biofeedback methods (with a sixth category combining them): electroencephalography, electrocardiography, eye tracking, electrodermal activity, electromyography, and multi-modal interaction. The review describes the properties, sensor technologies, and the type of data gathered for every included biofeedback method, and presents their respective interaction techniques. It summarizes a set of opportunities and challenges for each included method, based on the results from previous work, and discusses these findings. It also analyzes how these interaction techniques are distributed between different common game genres. The review is beneficial for people interested in biofeedback methods and their potential use for novel interaction techniques in future video games. © 2021 ACM.

In the development of novel algorithms and techniques in virtual and augmented reality (VR/AR), it is crucial to take human visual perception into account. For example, when hardware resources are a restraining factor, the limitations of the human visual system can be exploited in the creation and evaluation of new effective techniques. Over the last decades, visual perception evaluation studies have become a vital part of the design, development, and evaluation of immersive computer graphics applications. This course aims at introducing the attendees to the basic concepts of visual perception applied to computer graphics and it offers an overview of recent perceptual evaluation studies that have been conducted with head-mounted displays (HMDs) in the context of VR and AR applications. During this course, we call attention to the latest published courses and surveys on visual perception applied to computer graphics and interaction techniques. Through an extensive search in the literature, we have identified six main areas in which recent visual perceptual evaluation studies have been focused on: Distance perception, avatar perception, image quality, interaction, motion perception, and cybersickness. Trends, main results, and open challenges are discussed for each area and accompanied with relevant references offering the attendees a wide introduction and perspective on the topic. © 2019 Owner/Author.

Biofeedback interaction offers interesting opportunities for video games since it allows player physiological information to be used in novel interaction techniques. Despite several contributions in the area, biofeedback interaction faces a set of challenges relating to its design and implementation. First, it has mainly been used as a method to replace more traditional interaction devices, such as gamepads, mice or keyboards. Also, few of the previous interaction techniques have made an essential use of physiological data: exploring possibilities that could only be developed by involving physiological inputs.

This dissertation explores how different physiological methods, such as electroencephalography, eye tracking, electrocardiography, electrodermal activity, or electromyography, could be used in the design and development of natural user interaction techniques that might be applied to entertainment video games, highlighting technical details for the appropriate use of physiological signals. The research also discusses interaction design principles from a human-computer interaction perspective, evaluates several novel biofeedback interaction techniques with a set of user studies, and proposes ethical considerations for the appropriate exposure to virtual reality and physiological sensor technology.

Results show that the use of biofeedback inputs in novel interaction techniques, vary in complexity and functionality depending on the type of measurements used. They also showed that biofeedback interaction can positively affect player experience since it allows games and virtual reality applications to synchronize with player physiology, making of playing games a personalized experience. Results highlighted that biofeedback interaction can significantly affect player performance, being influenced by the interaction complexity and the reliability of the sensor technology used.

An important aspect of virtual reality (VR) interfaces are novel natural user interactions (NUIs). The increased use of VR games requires the evaluation of novel interaction techniques that allow efficient manipulations of 3D elements using the hands of the player. Examples of VR devices that support these interactions include the HTC Vive controller and the Leap Motion sensor. This paper presents a quantitative and qualitative evaluation of player performance and experience in a controlled experiment with 20 volunteering participants. The experiment evaluated the HTC Vive controller and the Leap Motion sensor when manipulating 3D objects in two VR games. The first game was a Pentomino puzzle and the second game consisted of a ball-throwing task. Four interaction techniques (picking up, dropping, rotating, and throwing objects) were evaluated as part of the experiment. The number of user interactions with the Pentomino pieces, the number of ball throws, and game completion time were metrics used to analyze the player performance. A questionnaire was also used to evaluate the player experience regarding enjoyment, ease of use, sense of control and user preference. The overall results show that there was a significant decrease in player performance when using the Leap Motion sensor for the VR game tasks. Participants also reported that hand gestures with the Leap Motion sensor were not as reliable as the HTC Vive controller. However, the survey showed positive responses when using both technologies. The paper also offers ideas to keep exploring the capabilities of NUI techniques in the future. Copyright © 2019 by SCITEPRESS – Science and Technology Publications, Lda. All rights reserved

The following article offers a set of recommendations that are considered relevant for designing and executing experiences with Virtual Reality (VR) technology. It presents a brief review of the history and evolution of VR, along with the physiological issues related to its use. Additionally, typical practices in VR, used by both academia and industry are discussed and contrasted. These were further analysed from an ethical perspective, guided by legal and Corporate Social Responsibility (CSR) frameworks, to understand their motivation and goals, and the rights and responsibilities related to the exposure of research participants and final consumers to VR. Our results showed that there is a significant disparity between practices in academia and industry, and for industry specifically, there can be breaches of user protection regulations and poor ethical practices. The differences found are mainly in regards to the type of content presented, the overall setup of VR experiences, and the amount of information provided to participants or consumers respectively. To contribute to this issue, this study highlights some ethical aspects and also offers practical considerations that aim, not only to have more appropriate practices with VR in public spaces but also to motivate a discussion and reflection to ease the adoption of this technology in the consumer market.