H προβολή υποσυνείδητων μηνυμάτων είναι η διαδικασία έκθεσης ερεθισμάτων κάτω από το κατώφλι της συνειδητοποίησης. Με τον τρόπο αυτό μπορεί να επηρεαστούν οι σκέψεις, τα συναισθήματα και ενέργειες του ανθρώπου. Η υποσυνείδητη αντίληψη συμβαίνει όταν οι πληροφορίες αποθηκεύονται στο ανθρώπινο μυαλό, χωρίς ο δέκτης να έχει συνειδητά επίγνωση του προβλήματος. Οι πληροφορίες φτάνουν στο μυαλό, γιατί ενώ δεν είναι συνειδητά αντιληπτές, γίνονται αντιληπτές από το υποσυνείδητο κομμάτι του εγκεφάλου. Αντικείμενο της παρούσας διπλωματικής εργασίας είναι η αποτίμηση των πιθανών διαφορών στις καταγραφές ηλεκτροεγκεφαλογραφήματος (ΕΕG) και προκλητών δυναμικών (ERPs) κατά την υποβολή ενός ατόμου σε οπτικά υποσυνείδητα ερεθίσματα σε σύγκριση με καταγραφές χωρίς ερέθισμα. Στην εργασία χρησιμοποιήθηκε ένα ερευνητικό πρωτόκολλο το οποίο εξετάζει το πώς επηρεάζουν τα υποσυνείδητα ερεθίσματα τη λήψη αποφάσεων και την εγκεφαλική λειτουργία. Στο πρώτο μέρος της εργασίας (κεφάλαια 1 και 2) γίνεται μια συνοπτική αναφορά στις κυριότερες μεθόδους απεικόνισης εγκεφάλου, όπως το ηλεκτροεγκεφαλογράφημα και την λειτουργική απεικόνιση Μαγνητικού Συντονισμού καθώς και στον συνδυασμό τους για πιο ικανοποιητικά αποτελέσματα. Το κεφάλαιο 3 αναφέρεται κυρίως σε θέματα σχετικά τα προκλητά δυναμικά, καθώς και την υποσυνείδητη αντίληψη. Στο κεφάλαιο 4 περιγράφεται η πειραματική διαδικασία και η μετρητική διάταξη που χρησιμοποιήθηκε καθώς και η παρουσίαση της επεξεργασίας των μετρήσεων μέσω του eeglab. Τέλος, στο κεφάλαιο 5 παρουσιάζονται τα αποτελέσματα της επεξεργασίας σε διαγράμματα προκλητών δυναμικών και φασματικής ισχύος καθώς επίσης και τα συμπεράσματα της εργασίας αυτής. / The display of subliminal messages is the process of stimuli exposure below the threshold of awareness. Through this procedure the thoughts, feelings and actions of a human can be influenced. The subliminal perception occurs when information stored in the human mind without the receiver being consciously aware of it. The information reaching the brain is perceived by the subconscious part of the brain. The object of this diploma thesis is to assess the possible differences in electroencephalogram (EEG) and event - related potentials (ERPs) recordings during the presentation of visual subliminal stimuli compared to non – subliminal conditions. A protocol that examines how subliminal stimuli influence the decision making and the cerebral operation is used. In the first part of the thesis (chapters 1 and 2) there is a brief review of the main brain imaging methods such as EEG and fMRI as well as the combination of them. Chapter 3 reveals issues about event - related potentials and mostly about subliminal perception. In chapter 4, the experiment and the measuring devices used are described, and there is also a presentation of the analysis by using the eeglab. Finally, chapter 5 includes the results of analysis on event - related potential and spectral power graphs, as well as the conclusions of this work.

One of the major problems in human computer interaction in a 3D virtual world is the extreme difficulty to deal with vast quantities of information in everyday life. This condition leads to problems such as indecisions of the human that outlines stress factors and causes an undesirable user experience. Part of the problem is that little findings have been contributed in research to this problem of assisting the human to make decisions quickly and provide rapid responses in respect to user experience. User experience evaluation of the human’s communication appears well situated to problems of this nature as it can be analyzed based upon interactive performance factors that help in the decision making process. For this reason, scenarios, adaptive narratives and frameworks were investigated and created as a potential tool to improve the human’s experience using cues of user’s interest related suggestions. For the purpose of a fluent interaction, a balance between passive and active interaction is aimed at and at last to achieve an immersive user experience an adaptive interactive narrative is generated that supports customizable feedback. To introduce a sophisticated version of a framework and design techniques, literature reviews, video recordings, questionnaires and personal experience evaluation have been conducted. A new platform for immersive interactions in a 3D virtual world has evolved. However, it turned out to be surprisingly difficult to evaluate the design in a setting that includes new technologies, where not much research has been done before. Based on these difficulties, the concept of three design techniques were developed and employed, in order to deal with the issue of decision-making that exists in daily life. These three techniques represent the scientific contribution to the stated major problems such as balanced interaction, immersive user experience and customizable data. This Master thesis discusses and concludes a generalizable framework on the result that was obtained when the adaptive narrative was created with its vast quantity of information that is applicable into other related installations in the commercial product design industry. / Ett av de stora problemen i människa-dator interaktion i en virtuell 3D- värld är det extremt svårt att hantera stora mängder information i vardagen. Detta tillstånd leder till problem såsom indecisions av människan som beskriver stressfaktorer och orsakar en oönskad användarupplevelse. En del av problemet är att små fynd har bidragit i forskningen på detta problem är att bistå människor att fatta beslut snabbt och ge snabba svar i förhållande till användarens upplevelse. Användare erfarenhet utvärdering av människans kommunikation verkar bra läge att problem av detta slag eftersom den kan analyseras baserat på interaktiva prestanda faktorer som hjälper i beslutsprocessen. Av denna anledning har scenarier, adaptiva berättelser och ramverk utreds och skapades som ett potentiellt verktyg för att förbättra människans erfarenhet av att använda ledtrådar i användarens intresse relaterade förslag. För en flytande interaktion, är en balans mellan passiv och aktiv samverkan som syftar till och till sist för att uppnå en uppslukande användarupplevelse en adaptiv interaktivt berättande genereras som stöder anpassningsbara återkoppling. Att införa en sofistikerad version av en ram och design tekniker, litteraturstudier, videoinspelningar, frågeformulär och personlig erfarenhet utvärdering har genomförts. En ny plattform för uppslukande interaktioner i en virtuell 3D- värld har utvecklats. Dock visade det sig vara förvånansvärt svårt att utvärdera designen i en miljö som innehåller ny teknik, där inte mycket forskning har gjorts tidigare. Baserat på dessa svårigheter, var begreppet tre design tekniker utvecklas och utnyttjas, i syfte att ta itu med frågan om beslutsfattande som finns i det dagliga livet. Dessa tre tekniker utgör den vetenskapliga bidrag till de angivna allvarliga problem såsom balanserad växelverkan, uppslukande användarupplevelse och anpassade uppgifter. Detta examensarbete behandlar och avslutar en generalizable ram på resultatet som erhölls när den adaptiva berättelsen skapades med dess stora mängd information som är tillämplig i andra installationer i kommersiella produkten designbranschen.

Research to determine what subliminal presentation accomplishes and its effects upon the learning process is very limited. The possibility of presenting subliminal information in a passive manner to reinforce the learning process and the possibility that this presentation can aid in the absorption of the information needed to learn is examined. A previous study examined this possibility using a text editor as the test instrument. In this thesis, a direct manipulation interface using a spreadsheet which visually presents tasks is examined to determine if this environment might be more effective with a learning medium using subliminal perception, then was the case of a text editor. This approach is based on the idea that, in contrast to a text editor, with direct manipulation the user would be completely focused on the computer screen where the subliminal message is presented increasing the chances for feedback. The results of this study show no significant difference between subjects who were getting subliminal help screen presentations and those who were getting either subliminal garbage screen presentations or blank screen presentations. This is in conflict with previous research.

In the course of development organisms learn to associate their actions with the effects these actions have in the environment. Recent studies have shown that perceiving or anticipating action-effects automatically activates actions, which formerly have been experienced to cause these effects (Elsner & Hommel, 2001). Using subliminal priming paradigms and electrophysiological measures I investigated whether subliminally (i.e., not consciously perceivable) presented action-effects can automatically activate associated actions and if so, whether this response priming by action-effects can bias free-choice actions. Secondly I investigated whether action-effects with different emotional valences influence response selection differently. To address the first question three experiments were performed. Each experiment consisted of two experimental phases. The first phase, the acquisition-phase, was a learning phase were simple key-press actions were associated with simple visual stimuli (i.e., action-effects; diamond or square) that were contingent on the actions. Immediately after the acquisition-phase the test-phase followed, in which participants performed free-choice actions after the presentation of a Go-signal. In Experiments 2 and 3 a NoGo-signal indicating that responses had to be withheld could appear with the same likelihood as the Go-signal. Unknown to the participants, one of the former action-effects (diamond or square) was presented subliminally prior to each Go- and NoGo-signal to investigate the influence of unconscious action-effects on response selection. Taken together, the results of the test-phases provided strong evidence that even subliminally presented (i.e., unconscious) action-effects can automatically activate associated responses. The response priming by action-effects became evident in the lateralized readiness potential (LRP), an electrophysiological indicator of specific response activation processes. Under certain circumstanced this automatic response activation can bias free-choice actions although participants experienced the actions as freely chosen. In the test-phase of the first experiment more acquisition-phase-consistent than –inconsistent responses were chosen. If, for instance, a left key-press had been associated with a square during the acquisition-phase, the left key was chosen significantly more often after the subliminal presentation of a square in the test-phase. At least three factors seemed to influence which responses were chosen and executed: The strength of the priming effect, the complexity of the task (i.e., pure Go-blocks or intermixed Go/NoGo-blocks), and the elapsed time between the prime stimulus and the Go-signal. To address the second question simple key-press actions were linked to action-effects with different emotional valences (positive vs. negative pictures accompanied by high or low tones) during the acquisition-phase. In the subsequent test-phase, the effects-tones that had been associated with negative or positive pictures were presented and followed by a Go-signal, after which participants had to freely choose to press one of the two response keys. Results indicated that the anticipation of the emotional valence of an action-effect influenced free-choice action. Whereas the effect-tones induced a clear response bias (i.e., more acquisition-consistent than –inconsistent key-choices) if they had been associated with a positive emotional valence, this response bias was not reliable for action-effects associated with negative emotional features. In summary, the present results provide further proof for ideomotor theories of action control (James, 1890; Elsner & Hommel, 2001) which state that actions are automatically activated by anticipating their consequences.

Certaines études ont montré que des odeurs subliminales – odeurs d'intensité très faible activant le système olfactif mais non perçues consciemment – peuvent impacter le comportement alimentaire. Cependant, les mécanismes sensoriels et cognitifs impliqués dans le traitement des odeurs subliminales demeurent mal connus. Ce travail de thèse avait pour but d'explorer les activations cérébrales induites par des odeurs subliminales au moyen de l'Imagerie par Résonance Magnétique fonctionnelle. Durant les acquisitions IRM, les participants sont exposés à leur insu à deux odeurs présentées à intensité subliminale puis supraliminale. Quatre réseaux cérébraux mis en évidence par Analyse en Composantes Indépendantes s’avèrent spécifiques de la condition subliminale. Ces réseaux ne sont pas propres au traitement des odeurs et semblent liés à des processus attentionnels et de contrôle exécutif. La modulation de leur activité par des odeurs subliminales apporte des éléments nouveaux pour comprendre l’impact de ces odeurs sur le comportement, et suggère des applications possibles d'utilisation de ces odeurs pour réguler le comportement alimentaire. / Some studies showed that subliminal odours – odours of very low intensity which activate the olfactory system but are not consciously perceived – can impact food behaviours. However, the sensory and cognitive mechanisms involved in subliminal odours processing remain poorly known. This work aims exploring cerebral activity induced by subliminal odours by the means of functional Magnetic Resonance Imaging. During MRI acquisitions, participants were unknowingly exposed to two odours presented at subliminal intensity and then at supraliminal intensity. Four cerebral networks highlighted by Independent Component Analysis (ICA) prove to be specific to the subliminal condition. These networks are not particular to olfactory processing and seem to be linked to attentional and executive control processes. The modulation of their activity by subliminal odours brings new elements to understand the impact of these odours on behaviour, and suggests possible applications for using these odours to regulate food behaviour.

How does the brain generate our experience of being in control over our actions and their effects? Here I argue that the perception of events as self-caused emerges from a comparison between anticipated and actual action-effects: if the representation of an event that follows an action is activated before the action, the event is experienced as caused by one’s own action, whereas in the case of a mismatch it will be attributed to an external cause rather than to the self. In a subliminal priming paradigm I show that participants overestimated how much control they had over objectively uncontrollable stimuli, which appeared after free- or forced-choice actions, when a masked prime activated a representation of the stimuli immediately before each action. This prime-induced control-illusion was independent from whether primes were consciously perceived. Results indicate that the conscious experience of control is modulated by unconscious anticipations of action-effects.

Background. Previous studies have highlighted the role of the brain reward and cognitive control systems in the etiology of anorexia nervosa (AN). In an attempt to disentangle the relative contribution of these systems to the disorder, we used functional magnetic resonance imaging (fMRI) to investigate hemodynamic responses to reward-related stimuli presented both subliminally and supraliminally in acutely underweight AN patients and age-matched healthy controls (HC). Methods. fMRI data were collected from a total of 35 AN patients and 35 HC, while they passively viewed subliminally and supraliminally presented streams of food, positive social, and neutral stimuli. Activation patterns of the group × stimulation condition × stimulus type interaction were interrogated to investigate potential group differences in processing different stimulus types under the two stimulation conditions. Moreover, changes in functional connectivity were investigated using generalized psychophysiological interaction analysis. Results. AN patients showed a generally increased response to supraliminally presented stimuli in the inferior frontal junction (IFJ), but no alterations within the reward system. Increased activation during supraliminal stimulation with food stimuli was observed in the AN group in visual regions including superior occipital gyrus and the fusiform gyrus/parahippocampal gyrus. No group difference was found with respect to the subliminal stimulation condition and functional connectivity. Conclusion. Increased IFJ activation in AN during supraliminal stimulation may indicate hyperactive cognitive control, which resonates with clinical presentation of excessive self-control in AN patients. Increased activation to food stimuli in visual regions may be interpreted in light of an attentional food bias in AN.

How does the brain generate our experience of being in control over our actions and their effects? Here I argue that the perception of events as self-caused emerges from a comparison between anticipated and actual action-effects: if the representation of an event that follows an action is activated before the action, the event is experienced as caused by one’s own action, whereas in the case of a mismatch it will be attributed to an external cause rather than to the self. In a subliminal priming paradigm I show that participants overestimated how much control they had over objectively uncontrollable stimuli, which appeared after free- or forced-choice actions, when a masked prime activated a representation of the stimuli immediately before each action. This prime-induced control-illusion was independent from whether primes were consciously perceived. Results indicate that the conscious experience of control is modulated by unconscious anticipations of action-effects.

Primad information är lättare tillgängligt i minnet och kan således lättare bli igenkänt. Förutsättningar för priming är bland annat subliminal perception, mål, tillförlitlighet, icke vaksamt och icke vanemässigt. Studiens syfte är att få bredare förståelse gällande subliminal primings påverkan. Frågeställningen var om kunder i en affär kan manipuleras, primas, till att ta en specifik kulör på plastpåse vid kassan samt om det finns någon könsskillnad vid effekten av priming. Deltagarna var 490 kunder, varav 333 män. Två olika skyltar med olika kulörer placerades vid kassan. Det noterades om kunderna valde den primade kulören på plastpåse eller inte. Kontrollgruppen bestod av 117 personer och dessa fick inte se någon skylt. Resultatet visade en signifikant skillnad, deltagarna valde samma kulör på plastpåse som skylten. Inga könsskillnader påträffades. Forskning visar att primingeffekter kan motstridas genom att individen gör sig medveten av potentiell omedveten påverkan. / Primed information is more accessible in memory and can thus easily be recognized. Prerequisites for priming include subliminal perception, goals, reliability, non alert and non habitually. The study aims to gain broader understanding regarding subliminal primings influence. The purpose of this thesis was to see whether the customers in a store could be manipulated, primed, to take a specific colour on plastic bags at checkout and if there are any gender differences in the effect of priming. Participants were 490 customers, of whom 333 men. Two different signs with different colours were placed at the checkout. It was noted if customers chose the primed colour of the plastic bag or not. The results showed a significant difference, the participants chose the same colour on the plastic bag as the sign. No gender differences were found. Research shows that priming effects can be opposed if people make themselves aware of potential unconscious influences.

La modélisation de l’expérience de l’utilisateur dans les Interactions Homme-Machine est un enjeu important pour la conception et le développement des systèmes adaptatifs intelligents. Dans ce contexte, une attention particulière est portée sur les réactions émotionnelles de l’utilisateur, car elles ont une influence capitale sur ses aptitudes cognitives, comme la perception et la prise de décision. La modélisation des émotions est particulièrement pertinente pour les Systèmes Tutoriels Émotionnellement Intelligents (STEI). Ces systèmes cherchent à identifier les émotions de l’apprenant lors des sessions d’apprentissage, et à optimiser son expérience d’interaction en recourant à diverses stratégies d’interventions. Cette thèse vise à améliorer les méthodes de modélisation des émotions et les stratégies émotionnelles utilisées actuellement par les STEI pour agir sur les émotions de l’apprenant. Plus précisément, notre premier objectif a été de proposer une nouvelle méthode pour détecter l’état émotionnel de l’apprenant, en utilisant différentes sources d’informations qui permettent de mesurer les émotions de façon précise, tout en tenant compte des variables individuelles qui peuvent avoir un impact sur la manifestation des émotions. Pour ce faire, nous avons développé une approche multimodale combinant plusieurs mesures physiologiques (activité cérébrale, réactions galvaniques et rythme cardiaque) avec des variables individuelles, pour détecter une émotion très fréquemment observée lors des sessions d’apprentissage, à savoir l’incertitude. Dans un premier lieu, nous avons identifié les indicateurs physiologiques clés qui sont associés à cet état, ainsi que les caractéristiques individuelles qui contribuent à sa manifestation. Puis, nous avons développé des modèles prédictifs permettant de détecter automatiquement cet état à partir des différentes variables analysées, à travers l’entrainement d’algorithmes d’apprentissage machine. Notre deuxième objectif a été de proposer une approche unifiée pour reconnaître simultanément une combinaison de plusieurs émotions, et évaluer explicitement l’impact de ces émotions sur l’expérience d’interaction de l’apprenant. Pour cela, nous avons développé une plateforme hiérarchique, probabiliste et dynamique permettant de suivre les changements émotionnels de l'apprenant au fil du temps, et d’inférer automatiquement la tendance générale qui caractérise son expérience d’interaction à savoir : l’immersion, le blocage ou le décrochage. L’immersion correspond à une expérience optimale : un état dans lequel l'apprenant est complètement concentré et impliqué dans l’activité d’apprentissage. L’état de blocage correspond à une tendance d’interaction non optimale où l'apprenant a de la difficulté à se concentrer. Finalement, le décrochage correspond à un état extrêmement défavorable où l’apprenant n’est plus du tout impliqué dans l’activité d’apprentissage. La plateforme proposée intègre trois modalités de variables diagnostiques permettant d’évaluer l’expérience de l’apprenant à savoir : des variables physiologiques, des variables comportementales, et des mesures de performance, en combinaison avec des variables prédictives qui représentent le contexte courant de l’interaction et les caractéristiques personnelles de l'apprenant. Une étude a été réalisée pour valider notre approche à travers un protocole expérimental permettant de provoquer délibérément les trois tendances ciblées durant l’interaction des apprenants avec différents environnements d’apprentissage. Enfin, notre troisième objectif a été de proposer de nouvelles stratégies pour influencer positivement l’état émotionnel de l’apprenant, sans interrompre la dynamique de la session d’apprentissage. Nous avons à cette fin introduit le concept de stratégies émotionnelles implicites : une nouvelle approche pour agir subtilement sur les émotions de l’apprenant, dans le but d’améliorer son expérience d’apprentissage. Ces stratégies utilisent la perception subliminale, et plus précisément une technique connue sous le nom d’amorçage affectif. Cette technique permet de solliciter inconsciemment les émotions de l’apprenant, à travers la projection d’amorces comportant certaines connotations affectives. Nous avons mis en œuvre une stratégie émotionnelle implicite utilisant une forme particulière d’amorçage affectif à savoir : le conditionnement évaluatif, qui est destiné à améliorer de façon inconsciente l’estime de soi. Une étude expérimentale a été réalisée afin d’évaluer l’impact de cette stratégie sur les réactions émotionnelles et les performances des apprenants. / Modeling the user’s experience within Human-Computer Interaction is an important challenge for the design and development of intelligent adaptive systems. In this context, a particular attention is given to the user’s emotional reactions, as they decisively influence his cognitive abilities, such as perception and decision-making. Emotion modeling is particularly relevant for Emotionally Intelligent Tutoring Systems (EITS). These systems seek to identify the learner’s emotions during tutoring sessions, and to optimize his interaction experience using a variety of intervention strategies. This thesis aims to improve current methods on emotion modeling, as well as the emotional strategies that are presently used within EITS to influence the learner’s emotions. More precisely, our first objective was to propose a new method to recognize the learner’s emotional state, using different sources of information that allow to measure emotions accurately, whilst taking account of individual characteristics that can have an impact on the manifestation of emotions. To that end, we have developed a multimodal approach combining several physiological measures (brain activity, galvanic responses and heart rate) with individual variables, to detect a specific emotion, which is frequently observed within computer tutoring, namely : uncertainty. First, we have identified the key physiological indicators that are associated to this state, and the individual characteristics that contribute to its manifestation. Then, we have developed predictive models to automatically detect this state from the analyzed variables, trough machine learning algorithm training. Our second objective was to propose a unified approach to simultaneously recognize a combination of several emotions, and to explicitly evaluate the impact of these emotions on the learner’s interaction experience. For this purpose, we have developed a hierarchical, probabilistic and dynamic framework, which allows one to track the learner’s emotional changes over time, and to automatically infer the trend that characterizes his interaction experience namely : flow, stuck or off-task. Flow is an optimal experience : a state in which the learner is completely focused and involved within the learning activity. The state of stuck is a non-optimal trend of the interaction where the learner has difficulty to maintain focused attention. Finally, the off-task behavior is an extremely unfavorable state where the learner is not involved anymore within the learning session. The proposed framework integrates three-modality diagnostic variables that sense the learner’s experience including : physiology, behavior and performance, in conjunction with predictive variables that represent the current context of the interaction and the learner’s personal characteristics. A human-subject study was conducted to validate our approach through an experimental protocol designed to deliberately elicit the three targeted trends during the learners’ interaction with different learning environments. Finally, our third objective was to propose new strategies to positively influence the learner’s emotional state, without interrupting the dynamics of the learning session. To this end, we have introduced the concept of implicit emotional strategies : a novel approach to subtly impact the learner’s emotions, in order to improve his learning experience. These strategies use the subliminal perception, and more precisely a technique known as affective priming. This technique aims to unconsciously solicit the learner’s emotions, through the projection of primes charged with specific affective connotations. We have implemented an implicit emotional strategy using a particular form of affective priming namely : the evaluative conditioning, which is designed to unconsciously enhance self-esteem. An experimental study was conducted in order to evaluate the impact of this strategy on the learners’ emotional reactions and performance.