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The prevalence and complexity of human-computer interaction makes a general understanding of human cognition important in design and development. Knowledge of some basic, relatively simple, principles for human brain function can significantly help such understanding in the interdisciplinary field of research and development Human-Computer Interaction (HCI) where no one can be an expert at everything. This paper explains a few such principles, relates them to human-computer interaction, and illustrates their potential. Most of these ideas are not new, but wider appreciation of the potential power of basic principles is only recently emerging as a result of developments within cognitive neuroscience and information theory. The starting point in this paper is the concept of mental simulation. Important and useful properties of mental simulations are explained using basic principles such as the free-energy principle. These concepts and their properties are further related to HCI by drawing on similarities to the theoretical framework of activity theory. Activity theory is particularly helpful to relate simple but abstract principles to real world applications and larger contexts. Established use of activity theory as a theoretical framework for HCI also exemplifies how theory may benefit HCI in general. Briefly, two basic principles that permeate this perspective are: the need for new skills and knowledge to build upon and fit into what is already there (grounding) and the importance of predictions and prediction errors (simulation).

Recent developments in general theories of cognition and brain function make it possible to consider the concept of presence from a new perspective, based in general principles of brain function. The importance of interaction with reality for the development and function of the brain and human cognition is increasingly emphasized. The brain is explained as implementing a generative model of the current environment. Whether this environment is real or virtual does not matter. Mental simulations are created for whatever one interacts with, when possible. This view provides a basis for relating human experiences in virtual environments to several theories that explain cognition and brain function on many levels, from ultimate evolutionary motivations to plausible neural implementations. The purpose of this paper is not to provide yet another definition of presence but to suggest explanations of phenomena commonly related to presence, with a basis in general principles of brain function. Such principles are employed to explain how, and why, interaction with our environment, and internalization of objects and tools therein, play an essential role in human cognition. This provides a rich basis for further analysis of how central aspects of presence, such as breaks in presence or the perceptual illusion of non-mediation, may work on a fundamental level. More general descriptions of such phenomena have advantages such as being easier to relate to new contexts and technologies, and opening up for additional inspiration and confirmation from other disciplines such as cognitive neuroscience. In addition to an account of general principles for brain function and a discussion about the concept of presence in light of these, this paper also relates this discussion to a number of previous accounts of presence, and to practical implications and applications for interaction design.

The combination of virtual reality (VR) and brain measurements is a promising development of HCI, but the maturation of this paradigm requires more knowledge about how brain activity is influenced by parameters of VR applications. To this end we investigate the influence of two prominent VR parameters, 3d-motion and interactivity, while brain activity is measured for a mental rotation task, using functional MRI (fMRI). A mental rotation network of brain areas is identified, matching previous results. The addition of interactivity increases the activation in core areas of this network, with more profound effects in frontal and preparatory motor areas. The increases from 3d-motion are restricted to primarily visual areas. We relate these effects to emerging theories of cognition and potential applications for brain-computer interfaces (BCIs). Our results demonstrate one way to provoke increased activity in task-relevant areas, making it easier to detect and use for adaptation and development of HCI.

The concept of presence is commonly related to whether or not a user feels, acts, and reacts as if he/she were in a real familiar environment when using a virtual reality (VR) application. Understanding the neural correlates of presence may provide a foundation for objective measurements of presence and important constraints for theoretical explanations of presence. Discussions about the neural basis for presence are relatively common, but brain imaging has rarely been applied to investigating this issue. Previous studies have focused on detecting average differences between conditions that correlate with differences in reported presence. In this study we focused on breaks in presence and associated periods of disrupted presence as an important complement to previous work. Specifically, we measured brain activity with functional magnetic resonance imaging (fMRI) during execution of an everyday task in a naturalistic virtual environment (VE). Time periods of disrupted presence were identified by subject reports indicating something strange in the current environment, interpreted as a violation of expectations related to the sense of presence. Disrupted presence was associated with increased activity in the frontopolar cortex (FPC), lateral occipito-temporal cortex (LOTC), the temporal poles (TP), and the posterior superior temporal cortex (pSTC). We relate these areas to integration of key aspects of a presence experience, relating the (changing) situation to management of task and goals (FPC), interpretation of visual input (LOTC), emotional evaluation of the context (TP) and possible interactions (pSTC). Modulation of the activity level in these brain areas is consistent with an interpretation of disrupted presence as a re-evaluation of key aspects of a subjective mental reality, updating the synchronization with the virtual environment as previous predictions fail. Such a subjective mental reality may also be related to a self-centered type of mentalization, providing a link to accounts of presence building on the self.

Computerized cognitive training is an area where the use of computer games technology and methods has a great potential, for example, to address cognitive decline in an aging population. Adaptive games, in particular, are of great interest as the level of training has often been suggested as important for efficient training. An important part of any adaptive application is measuring and interpreting whatever the game should adapt to. In this paper we describe our work on using the Emotiv Epoc commercial EEG headset in order to measure and adapt to the user's level of arousal in two different applications. The first application is an adaptation of a classic cognitive training task (N-back) using game technologies to create a dynamic and (relatively) realistic version in a 3d-environment. The second application is a simple version of the classic space invaders game. In both applications EEG measurements recorded during initial training are used in a later phase to adapt the difficulty of the game automatically. While we managed to get this setup to work to a limited degree for some individuals, we failed to create a system where this method worked reliably across subjects and trials. In this paper, we describe what we tried, what worked, and some of the lessons we learned.