Influencing brain waves by evoked potentials as biometric approach: taking stock of the last six years of research

The scientific advances of recent years have made available to anyone affordable hardware devices capable of doing something unthinkable until a few years ago, the reading of brain waves. It means that through small wearable devices it is possible to perform an electroencephalography (EEG), albeit with less potential than those offered by high-cost professional devices. Such devices make it possible for researchers a huge number of experiments that were once impossible in many areas due to the high costs of the necessary hardware. Many studies in the literature explore the use of EEG data as a biometric approach for people identification, but, unfortunately, it presents problems mainly related to the difficulty of extracting unique and stable patterns from users, despite the adoption of sophisticated techniques. An approach to face this problem is based on the evoked potentials (EPs), external stimuli applied during the EEG reading, a noninvasive technique used for many years in clinical routine, in combination with other diagnostic tests, to evaluate the electrical activity related to some areas of the brain and spinal cord to diagnose neurological disorders. In consideration of the growing number of works in the literature that combine the EEG and EP approaches for biometric purposes, this work aims to evaluate the practical feasibility of such approaches as reliable biometric instruments for user identification by surveying the state of the art of the last 6 years, also providing an overview of the elements and concepts related to this research area

In-ear EEG biometrics for feasible and readily collectable real-world person authentication

The use of EEG as a biometrics modality has been investigated for about a decade, however its feasibility in real-world applications is not yet conclusively established, mainly due to the issues with collectability and reproducibility. To this end, we propose a readily deployable EEG biometrics system based on a `one-fits-all' viscoelastic generic in-ear EEG sensor (collectability), which does not require skilled assistance or cumbersome preparation. Unlike most existing studies, we consider data recorded over multiple recording days and for multiple subjects (reproducibility) while, for rigour, the training and test segments are not taken from the same recording days. A robust approach is considered based on the resting state with eyes closed paradigm, the use of both parametric (autoregressive model) and non-parametric (spectral) features, and supported by simple and fast cosine distance, linear discriminant analysis and support vector machine classifiers. Both the verification and identification forensics scenarios are considered and the achieved results are on par with the studies based on impractical on-scalp recordings. Comprehensive analysis over a number of subjects, setups, and analysis features demonstrates the feasibility of the proposed ear-EEG biometrics, and its potential in resolving the critical collectability, robustness, and reproducibility issues associated with current EEG biometrics

Authentication using c-VEP evoked in a mild-burdened cognitive task

In recent years, more and more researchers are devoting themselves to the studies about authentication based on biomarkers. Among a wide variety of biomarkers, code-modulated visual evoked potential (c-VEP) has attracted increasing attention due to its significant role in the field of brain-computer interface. In this study, we designed a mild-burdened cognitive task (MBCT), which can check whether participants focus their attention on the visual stimuli that evoke c-VEP. Furthermore, we investigated the authentication based on the c-VEP evoked in the cognitive task by introducing a deep learning method. Seventeen participants were recruited to take part in the MBCT experiments including two sessions, which were carried out on two different days. The c-VEP signals from the first session were extracted to train the authentication deep models. The c-VEP data of the second session were used to verify the models. It achieved a desirable performance, with the average accuracy and F1 score, respectively, of 0.92 and 0.89. These results show that c-VEP carries individual discriminative characteristics and it is feasible to develop a practical authentication system based on c-VEP

Predicting the Standard and Deviant Patterns In EEG Signals Based On Deep Learning Model

In the recent years, there has been a significant growth in the area of brain computer interference. The main aim of such area is to read the brain activities, formulate a specific/desired output and power a specific approach using such output. Electroencephalography (EEG) may provide an insight into the analysis procedure of the human behavior and the level of the attention. Using the deep learning based neural network has a great success in different applications recently,such as making a decision, classifying a pattern and predicting an outcome by learning from a set of data and build the right weight matrices to represent the prediction outcome or the learning patterns. This research work proposes a novel model based on long short-term memory network to predict the standard and the deviant cases within EEG data sets. The EEG signals are acquired utilizing all the 128 electrodes that represent the 128 channels from infants aged between 5 and 7 months. Statistical approaches, principal component analysis (PCA) and autoregressive (AR) power spectral density estimate have been employed to extract the features from the EEG data sets. The proposed deep learning based model has shown great robustness dealing with different types of features extracted from the processed data sets. Very promising results have been achieved in predicting the standard and deviant cases. The standard case was presented with frequent, repetitive stimulus and the deviant case was presented with infrequent sounds

Embedding mobile learning into everyday life settings

The increasing ubiquity of smartphones has changed the way we interact with information and acquire new knowledge. The prevalence of personal mobile devices in our everyday lives creates new opportunities for learning that exceed the narrow boundaries of a school’s classroom and provide the foundations for lifelong learning. Learning can now happen whenever and wherever we are; whether on the sofa at home, on the bus during our commute, or on a break at work. However, the flexibility offered by mobile learning also creates its challenges. Being able to learn anytime and anywhere does not necessarily result in learning uptake. Without the school environment’s controlled schedule and teacher guidance, the learners must actively initiate learning activities, keep up repetition schedules, and cope with learning in interruption-prone everyday environments. Both interruptions and infrequent repetition can harm the learning process and long-term memory retention. We argue that current mobile learning applications insufficiently support users in coping with these challenges. In this thesis, we explore how we can utilize the ubiquity of mobile devices to ensure frequent engagement with the content, focusing primarily on language learning and supporting users in dealing with learning breaks and interruptions. Following a user-centered design approach, we first analyzed mobile learning behavior in everyday settings. Based on our findings, we proposed concepts and designs, developed research prototypes, and evaluated them in laboratory and field evaluations with a specific focus on user experience. To better understand users’ learning behavior with mobile devices, we first characterized their interaction with mobile learning apps through a detailed survey and a diary study. Both methods confirmed the enormous diversity in usage situations and preferences. We observed that learning often happens unplanned, infrequently, among the company of friends or family, or while simultaneously performing secondary tasks such as watching TV or eating. The studies further uncovered a significant prevalence of interruptions in everyday settings that affected users’ learning behavior, often leading to suspension and termination of the learning activities. We derived design implications to support learning in diverse situations, particularly aimed at mitigating the adverse effects of multitasking and interruptions. The proposed strategies should help designers and developers create mobile learning applications that adapt to the opportunities and challenges of learning in everyday mobile settings. We explored four main challenges, emphasizing that (1) we need to consider that Learning in Everyday Settings is Diverse and Interruption-prone, (2) learning performance is affected by Irregular and Infrequent Practice Behavior, (3) we need to move From Static to Personalized Learning, and (4) that Interruptions and Long Learning Breaks can Negatively Affect Performance. To tackle these challenges, we propose to embed learning into everyday smartphone interactions, which could foster frequent engagement with – and implicitly personalize – learning content (according to users’ interests and skills). Further, we investigate how memory cues could be applied to support task resumption after interruptions in mobile learning. To confirm that our idea of embedding learning into everyday interactions can increase exposure, we developed an application integrating learning tasks into the smartphone authentication process. Since unlocking the smartphone is a frequently performed action without any other purpose, our subjects appreciated the idea of utilizing this process to perform quick and simple learning interactions. Evidence from a comparative user study showed that embedding learning tasks into the unlocking mechanism led to significantly more interactions with the learning content without impairing the learning quality. We further explored a method for embedding language comprehension assessment into users’ digital reading and listening activities. By applying physiological measurements as implicit input, we reliably detected unknown words during laboratory evaluations. Identifying such knowledge gaps could be used for the provision of in-situ support and to inform the generation of personalized language learning content tailored to users’ interests and proficiency levels. To investigate memory cueing as a concept to support task resumption after interruptions, we complemented a theoretical literature analysis of existing applications with two research probes implementing and evaluating promising design concepts. We showed that displaying memory cues when the user resumes the learning activity after an interruption improves their subjective user experience. A subsequent study presented an outlook on the generalizability of memory cues beyond the narrow use case of language learning. We observed that the helpfulness of memory cues for reflecting on prior learning is highly dependent on the design of the cues, particularly the granularity of the presented information. We consider interactive cues for specific memory reactivation (e.g., through multiple-choice questions) a promising scaffolding concept for connecting individual micro-learning sessions when learning in everyday settings. The tools and applications described in this thesis are a starting point for designing applications that support learning in everyday settings. We broaden the understanding of learning behavior and highlight the impact of interruptions in our busy everyday lives. While this thesis focuses mainly on language learning, the concepts and methods have the potential to be generalized to other domains, such as STEM learning. We reflect on the limitations of the presented concepts and outline future research perspectives that utilize the ubiquity of mobile devices to design mobile learning interactions for everyday settings.Die Allgegenwärtigkeit von Smartphones verändert die Art und Weise wie wir mit Informationen umgehen und Wissen erwerben. Die weite Verbreitung von mobilen Endgeräten in unserem täglichen Leben führt zu neuen Möglichkeiten des Lernens, welche über die engen Grenzen eines Klassenraumes hinausreichen und das Fundament für lebenslanges Lernen schaffen. Lernen kann nun zu jeder Zeit und an jedem Ort stattfinden: auf dem Sofa Zuhause, im Bus während des Pendelns oder in der Pause auf der Arbeit. Die Flexibilität des mobilen Lernens geht jedoch zeitgleich mit Herausforderungen einher. Ohne den kontrollierten Ablaufplan und die Unterstützung der Lehrpersonen im schulischen Umfeld sind die Lernenden selbst dafür verantwortlich, aktiv Lernsitzungen zu initiieren, Wiederholungszyklen einzuhalten und Lektionen in unterbrechungsanfälligen Alltagssituationen zu meistern. Sowohl Unterbrechungen als auch unregelmäßige Wiederholung von Inhalten können den Lernprozess behindern und der Langzeitspeicherung der Informationen schaden. Wir behaupten, dass aktuelle mobile Lernanwendungen die Nutzer*innen nur unzureichend in diesen Herausforderungen unterstützen. In dieser Arbeit erforschen wir, wie wir uns die Allgegenwärtigkeit mobiler Endgeräte zunutze machen können, um zu erreichen, dass Nutzer*innen regelmäßig mit den Lerninhalten interagieren. Wir fokussieren uns darauf, sie im Umgang mit Unterbrechungen und Lernpausen zu unterstützen. In einem nutzerzentrierten Designprozess analysieren wir zunächst das Lernverhalten auf mobilen Endgeräten in alltäglichen Situationen. Basierend auf den Erkenntnissen schlagen wir Konzepte und Designs vor, entwickeln Forschungsprototypen und werten diese in Labor- und Feldstudien mit Fokus auf User Experience (wörtl. “Nutzererfahrung”) aus. Um das Lernverhalten von Nutzer*innen mit mobilen Endgeräten besser zu verstehen, versuchen wir zuerst die Interaktionen mit mobilen Lernanwendungen durch eine detaillierte Umfrage und eine Tagebuchstudie zu charakterisieren. Beide Methoden bestätigen eine enorme Vielfalt von Nutzungssituationen und -präferenzen. Wir beobachten, dass Lernen oft ungeplant, unregelmäßig, im Beisein von Freunden oder Familie, oder während der Ausübung anderer Tätigkeiten, beispielsweise Fernsehen oder Essen, stattfindet. Die Studien decken zudem Unterbrechungen in Alltagssituationen auf, welche das Lernverhalten der Nutzer*innen beeinflussen und oft zum Aussetzen oder Beenden der Lernaktivität führen. Wir leiten Implikationen ab, um Lernen in vielfältigen Situationen zu unterstützen und besonders die negativen Einflüsse von Multitasking und Unterbrechungen abzuschwächen. Die vorgeschlagenen Strategien sollen Designer*innen und Entwickler*innen helfen, mobile Lernanwendungen zu erstellen, welche sich den Möglichkeiten und Herausforderungen von Lernen in Alltagssituationen anpassen. Wir haben vier zentrale Herausforderungen identifiziert: (1) Lernen in Alltagssituationen ist divers und anfällig für Unterbrechungen; (2) Die Lerneffizienz wird durch unregelmäßiges Wiederholungsverhalten beeinflusst; (3) Wir müssen von statischem zu personalisiertem Lernen übergehen; (4) Unterbrechungen und lange Lernpausen können dem Lernen schaden. Um diese Herausforderungen anzugehen, schlagen wir vor, Lernen in alltägliche Smartphoneinteraktionen einzubetten. Dies führt zu einer vermehrten Beschäftigung mit Lerninhalten und könnte zu einer impliziten Personalisierung von diesen anhand der Interessen und Fähigkeiten der Nutzer*innen beitragen. Zudem untersuchen wir, wie Memory Cues (wörtl. “Gedächtnishinweise”) genutzt werden können, um das Fortsetzen von Aufgaben nach Unterbrechungen im mobilen Lernen zu erleichtern. Um zu zeigen, dass unsere Idee des Einbettens von Lernaufgaben in alltägliche Interaktionen wirklich die Beschäftigung mit diesen erhöht, haben wir eine Anwendung entwickelt, welche Lernaufgaben in den Entsperrprozess von Smartphones integriert. Da die Authentifizierung auf dem Mobilgerät eine häufig durchgeführte Aktion ist, welche keinen weiteren Mehrwert bietet, begrüßten unsere Studienteilnehmenden die Idee, den Prozess für die Durchführung kurzer und einfacher Lerninteraktionen zu nutzen. Ergebnisse aus einer vergleichenden Nutzerstudie haben gezeigt, dass die Einbettung von Aufgaben in den Entsperrprozess zu signifikant mehr Interaktionen mit den Lerninhalten führt, ohne dass die Lernqualität beeinträchtigt wird. Wir haben außerdem eine Methode untersucht, welche die Messung von Sprachverständnis in die digitalen Lese- und Höraktivitäten der Nutzer*innen einbettet. Mittels physiologischer Messungen als implizite Eingabe können wir in Laborstudien zuverlässig unbekannte Wörter erkennen. Die Aufdeckung solcher Wissenslücken kann genutzt werden, um in-situ Untestützung bereitzustellen und um personalisierte Lerninhalte zu generieren, welche auf die Interessen und das Wissensniveau der Nutzer*innen zugeschnitten sind. Um Memory Cues als Konzept für die Unterstützung der Aufgabenfortsetzung nach Unterbrechungen zu untersuchen, haben wir eine theoretische Literaturanalyse von bestehenden Anwendungen um zwei Forschungsarbeiten erweitert, welche vielversprechende Designkonzepte umsetzen und evaluieren. Wir haben gezeigt, dass die Präsentation von Memory Cues die subjektive User Experience verbessert, wenn der Nutzer die Lernaktivität nach einer Unterbrechung fortsetzt. Eine Folgestudie stellt einen Ausblick auf die Generalisierbarkeit von Memory Cues dar, welcher über den Tellerrand des Anwendungsfalls Sprachenlernen hinausschaut. Wir haben beobachtet, dass der Nutzen von Memory Cues für das Reflektieren über gelernte Inhalte stark von dem Design der Cues abhängt, insbesondere von der Granularität der präsentierten Informationen. Wir schätzen interaktive Cues zur spezifischen Gedächtnisaktivierung (z.B. durch Mehrfachauswahlfragen) als einen vielversprechenden Unterstützungsansatz ein, welcher individuelle Mikrolerneinheiten im Alltag verknüpfen könnte. Die Werkzeuge und Anwendungen, die in dieser Arbeit beschrieben werden, sind ein Startpunkt für das Design von Anwendungen, welche das Lernen in Alltagssituationen unterstützen. Wir erweitern das Verständnis, welches wir von Lernverhalten im geschäftigen Alltagsleben haben und heben den Einfluss von Unterbrechungen in diesem hervor. Während sich diese Arbeit hauptsächlich auf das Lernen von Sprachen fokussiert, haben die vorgestellten Konzepte und Methoden das Potential auf andere Bereiche übertragen zu werden, beispielsweise das Lernen von MINT Themen. Wir reflektieren über die Grenzen der präsentierten Konzepte und skizzieren Perspektiven für zukünftige Forschungsarbeiten, welche sich die Allgegenwärtigkeit von mobilen Endgeräten zur Gestaltung von Lernanwendungen für den Alltag zunutze machen

Change blindness: eradication of gestalt strategies

Arrays of eight, texture-defined rectangles were used as stimuli in a one-shot change blindness (CB) task where there was a 50% chance that one rectangle would change orientation between two successive presentations separated by an interval. CB was eliminated by cueing the target rectangle in the first stimulus, reduced by cueing in the interval and unaffected by cueing in the second presentation. This supports the idea that a representation was formed that persisted through the interval before being 'overwritten' by the second presentation (Landman et al, 2003 Vision Research 43149–164]. Another possibility is that participants used some kind of grouping or Gestalt strategy. To test this we changed the spatial position of the rectangles in the second presentation by shifting them along imaginary spokes (by ±1 degree) emanating from the central fixation point. There was no significant difference seen in performance between this and the standard task [F(1,4)=2.565, p=0.185]. This may suggest two things: (i) Gestalt grouping is not used as a strategy in these tasks, and (ii) it gives further weight to the argument that objects may be stored and retrieved from a pre-attentional store during this task

EEG-based Brain-Computer Interfaces (BCIs): A Survey of Recent Studies on Signal Sensing Technologies and Computational Intelligence Approaches and Their Applications.

Brain-Computer interfaces (BCIs) enhance the capability of human brain activities to interact with the environment. Recent advancements in technology and machine learning algorithms have increased interest in electroencephalographic (EEG)-based BCI applications. EEG-based intelligent BCI systems can facilitate continuous monitoring of fluctuations in human cognitive states under monotonous tasks, which is both beneficial for people in need of healthcare support and general researchers in different domain areas. In this review, we survey the recent literature on EEG signal sensing technologies and computational intelligence approaches in BCI applications, compensating for the gaps in the systematic summary of the past five years. Specifically, we first review the current status of BCI and signal sensing technologies for collecting reliable EEG signals. Then, we demonstrate state-of-the-art computational intelligence techniques, including fuzzy models and transfer learning in machine learning and deep learning algorithms, to detect, monitor, and maintain human cognitive states and task performance in prevalent applications. Finally, we present a couple of innovative BCI-inspired healthcare applications and discuss future research directions in EEG-based BCI research