Cette thèse vise à définir une nouvelle méthode d’enseignement pour les systèmes tutoriels intelligents dans le but d’améliorer l’acquisition des connaissances. L’apprentissage est un phénomène complexe faisant intervenir des mécanismes émotionnels et cognitifs de nature consciente et inconsciente. Nous nous intéressons à mieux comprendre les mécanismes inconscients du raisonnement lors de l’acquisition des connaissances. L’importance de ces processus inconscients pour le raisonnement est bien documentée en neurosciences, mais demeure encore largement inexplorée dans notre domaine de recherche. Dans cette thèse, nous proposons la mise en place d’une nouvelle approche pédagogique dans le domaine de l’éducation implémentant une taxonomie neuroscientifique de la perception humaine. Nous montrons que cette nouvelle approche agit sur le raisonnement et, à tour de rôle, améliore l’apprentissage général et l’induction de la connaissance dans un environnement de résolution de problème. Dans une première partie, nous présentons l’implémentation de notre nouvelle méthode dans un système tutoriel visant à améliorer le raisonnement pour un meilleur apprentissage. De plus, compte tenu de l’importance des mécanismes émotionnels dans l’apprentissage, nous avons également procédé dans cette partie à la mesure des émotions par des capteurs physiologiques. L’efficacité de notre méthode pour l’apprentissage et son impact positif observé sur les émotions a été validée sur trente et un participants. Dans une seconde partie, nous allons plus loin dans notre recherche en adaptant notre méthode visant à améliorer le raisonnement pour une meilleure induction de la connaissance. L’induction est un type de raisonnement qui permet de construire des règles générales à partir d’exemples spécifiques ou de faits particuliers. Afin de mieux comprendre l’impact de notre méthode sur les processus cognitifs impliqués dans ce type de raisonnement, nous avons eu recours à des capteurs cérébraux pour mesurer l’activité du cerveau des utilisateurs. La validation de notre approche réalisée sur quarante-trois volontaires montre l’efficacité de notre méthode pour l’induction de la connaissance et la viabilité de mesurer le raisonnement par des mesures cérébrales suite à l’application appropriée d’algorithmes de traitement de signal. Suite à ces deux parties, nous clorons la thèse par une discussion applicative en décrivant la mise en place d’un nouveau système tutoriel intelligent intégrant les résultats de nos travaux. / This thesis aims at defining a new learning method to improve knowledge acquisition for intelligent tutoring systems. Learning is a complex phenomenon interlinking both emotional and cognitive mechanisms on conscious and unconscious levels. We are interested in understanding the unconscious mechanisms involved in human reasoning for knowledge acquisition. The importance of these unconscious processes is well documented in neuroscience, but remains largely unexplored in our research field. In this thesis, we put forward a new pedagogical approach in the field of education based on a taxonomy of human perception in neuroscience. We show that this method improves on reasoning which in turn enhances overall learning and inductive capabilities for knowledge acquisition in a problem solving environment. In a first part, we present the implementation of our new method in a tutorial system to improve reasoning hence leading to better learning. Furthermore, acknowledging the importance of emotional mechanisms in learning, we therefore recorded, in this first part, the emotional reactions of users using physiological sensors. The effectiveness of our method for learning and its positive impact on emotions has been validated on 31 participants. In a second part, we go further in our research and enhance our approach in order to improve reasoning for a better induction of knowledge. Induction in a bottom-up logical reasoning approach where one constructs general rules from observed examples. To better understand the impact of our method on the cognitive processes involved in this type of reasoning, we used sensors to record the users’ brain electrical activity. The validation of our approach was carried out on a cohort of 43 volunteers. We showed the effectiveness of our method on the induction of knowledge and sustainability of measuring user’s reasoning by brain recordings after applying proper signal processing algorithms to the data. Following the two parts, we finish the thesis by presenting the implementation of a new intelligent tutoring system incorporating the results found throughout this work.

Bei einem Spaziergang im Mondlicht nehmen wir Ereignisse verschiedenster Intensität wahr. Vom blendenden Licht eines vorbeifahrenden Motorrads bis hin zu undeutlichen Schatten. Verarbeiten wir diese Ereignisse alle gleich? In dieser Arbeit untersuchte ich, wie das visuelle System auf Stimuli reagiert, die so niedrig in ihrer Intensität sind, dass wir sie nicht wahrnehmen. Frühere somatosensorische Studien zeigten eine kortikale Deaktivierung aufgrund subliminaler Stimulation. Diese wurde als Hemmungsmechanismus interpretiert zur Unterdrückung kortikalen Rauschens. Unterstützt wurde diese Aussage durch ein Verhaltensexperiment, in dem der Schwellwert für somatosensorische Stimuli bei subliminaler Stimulation erhöht war. Gibt es im visuellen System äquivalente Hemmungsmechanismen? In Studie I untersuchte ich die Wahrnehmung schwellnaher visueller Zielreize: die Wahrnehmung verschlechterte sich bei gleichzeitiger subliminaler Stimulation im selben Hemifield. Inhibitorische Interneurone könnten diesen Effekt hervorrufen. Gleichzeitig zeigten Nervenzell-Studien die Degeneration intrakortikaler Inhibition mit dem fortschreitendem Alter von Affen. In Studie II untersuchte ich daher Unterschiede inhibitorischer Mechanismen einer kleinen Gruppe von älteren Probanden und verglich diese mit den jüngeren Probanden aus Studie I. In Studie III, einer elektrophysiologischen Studie, führt subliminale Stimulation zu einer Verstärkung des Alpha-Rhythmus. Supraliminale Stimulation führt zu einer Verstärkung niedriger Frequenzen und einer Abschwächung des Alpha-Rhythmus. Die spezifische neuronale Signatur aufgrund subliminaler Stimulation deutet darauf hin, dass die neuronale Verarbeitung des Stimulus zu einer Verringerung der Aktivität in involvierten Arealen führt. Ein Rauschunterdrückungs-Mechanismus wurde im somatosensorischen System beschrieben und könnte für die verringerte Wahrnehmung der schwellnahen Zielreize bei subliminaler Stimulation verantwortlich sein. / Walking along a street on a moonlit night, we can perceive visual events at a wide range of intensities – from the blinding light of a passing motorcycle to faint shadows. Does the visual system react similarly to all of these events? Here, I investigated how the visual system reacts to stimuli that are so low in their intensity that they are not perceived. It has been shown that subliminal low-intensity somatosensory stimuli lead to a cortical deactivation or inhibition. This deactivation was interpreted as inhibition mechanism that usually protects the cortex against activation by noise. Also, a behavioural experiment showed an increased sensitivity threshold for peri-liminal stimuli during subliminal stimulation. Does a similar mechanism exist within the visual System? In Study I, I investigated the perception of visual peri-liminal target-stimuli under different conditions. The threshold for target-stimuli significantly increased when presented during subliminal stimulation on the same side as the target-stimulus. The underlying mechanism could be mediated through intracortical inhibition. Concurrently, studies in macaque senescent neurons suggest a degradation of intracortical inhibition with age. In Study II, I therefore investigated differences of inhibitory responses in a group of elderly subjects and compared the results to the young participants in Study I. In Study III, using electroencephalography, I show that subliminal stimulation leads to an alpha-band power increase, whereas supraliminal stimulation leads to a lower frequency increase and an alpha-band power decrease. Specific neural signature in response to subliminal stimulation indicate neural processing of the stimulus that lead to a down-regulation of areas involved in stimulus processing. This mechanism could serve a suppression of input noise that has been described in the somatosensory system and may lead to decreased detection of peri-liminal target-stimuli during subliminal stimulation.

Das Reizdarmsyndrom (RDS) ist eine funktionale Darmerkrankung mit einer Prävalenz von 10.000 – 20.000/100.000 in verschiedenen Kulturen. Keine einzelne physiologische oder psychologische Ursache konnte bisher isoliert werden. Ein sensitiver und spezifischer Maker sind herabgesetzte rektale Schmerzschwellen. Veränderungen der cerebralen viszerosensorischen und nozizeptiven Repräsentation sind mit Neuroimaging-Studien untersucht worden. Die Verarbeitung von Reizen unterhalb der Wahrnehmungsschwelle scheint sich von der Verarbeitung bewusster Reize zu unterscheiden. Wir untersuchten daher sub- und supraliminale rektale Wahrnehmung von 8 RDS-Patienten und 8 parallelisierten gesunden Kontrollprobanden. Die Reizschwelle wurde mit Hilfe eines Tracking-Paradigmas bestimmt. In einer funktionellen Magnetresonanztomographie (fMRT)-Studie wurden Reize unter, über und in der Nähe der Wahrnehmungsschwelle in einem pseudorandomisierten Blockdesign präsentiert. Bei supraliminaler Stimulation gesunder Probanden konnten der bekannte spinothalamische und vagale Pfad repliziert werden. Bei subliminaler Stimulation zeigte sich in einer Einzelauswertung eine ähnliche Verarbeitung, damit konnten die Vorergebnisse hier ebenfalls repliziert werden. In der Gruppenauswertung fand sich Aktivierung nur in Arealen, die bei supraliminaler Stimulation nicht aktiv waren. RDS-Patienten zeigten weniger Aktivität bei subliminaler und mehr bei liminaler Stimulation. Bei supraliminaler Stimulation zeigten sich unterschiedliche aktivierte Areale. Insbesondere war der Amygdala-Hippocampus-Komplex bei Patienten stärker aktiviert. Die Ergebnisse bei supraliminaler und liminaler Stimulation können als verstärkte Aufmerksamkeit auf eben wahrnehmbare Darmreize und als verstärkte emotionale Verarbeitung interpretiert werden. Bei der subliminalen Stimulation kann man schwächere Aktivität schmerzunterdrückender Netze annehmen oder von einem methodischen Artefakt ausgehen. / Irritable bowel syndrome (IBS) is a functional bowel disease with a prevalence of 10.000 - 20.000/100.000 across cultures. So far, no single physiological or psychological reason has been identified. Nevertheless, reduced rectal pain thresholds represent a sensitive and specific marker. Alterations in cerebral viscerosensory and nociceptive representation have been addressed using neuroimaging studies. Processing of stimuli below conscious perception level seems to differ from consciously perceived stimuli. Thus, we examined sub- and supraliminal rectal perception in 8 patients with IBS and 8 healthy matched control subjects. Perception thresholds were assessed by a tracking paradigm. In an functional magnetic resonance imaging (fMRI) study using a block design, stimuli below, above, or around the subjective perception threshold were presented in pseudo-randomized order. At supraliminal stimulation in healthy controls, results of previous studies were replicated and confirmed a spinothalamic and a vagal pathway of visceral sensory perception and suggested processing in amygdala and hippocampus. At subliminal stimulation in healthy controls, previous results were also replicated showing similar processing in single subject analysis. Results of a group analysis yielded only activity in areas not activated at supraliminal stimulation. IBS patients showed less pronounced activity during subliminal stimulation and much more pronounced activity at liminal stimulation. At supraliminal stimulation, different areas showed active in both groups. In particular, the amygdala-hippocampus complex was more active in patients. Results at liminal and supraliminal stimulation can be interpreted as enhanced attention to around-threshold rectal stimuli and more pronounced emotional processing of conciously perceived stimuli. Results at subliminal stimulation can be understood as weaker activity of perception-suppressing pathways or as methodological artifact.

Cette thèse vise à définir une nouvelle méthode d’enseignement pour les systèmes tutoriels intelligents dans le but d’améliorer l’acquisition des connaissances. L’apprentissage est un phénomène complexe faisant intervenir des mécanismes émotionnels et cognitifs de nature consciente et inconsciente. Nous nous intéressons à mieux comprendre les mécanismes inconscients du raisonnement lors de l’acquisition des connaissances. L’importance de ces processus inconscients pour le raisonnement est bien documentée en neurosciences, mais demeure encore largement inexplorée dans notre domaine de recherche. Dans cette thèse, nous proposons la mise en place d’une nouvelle approche pédagogique dans le domaine de l’éducation implémentant une taxonomie neuroscientifique de la perception humaine. Nous montrons que cette nouvelle approche agit sur le raisonnement et, à tour de rôle, améliore l’apprentissage général et l’induction de la connaissance dans un environnement de résolution de problème. Dans une première partie, nous présentons l’implémentation de notre nouvelle méthode dans un système tutoriel visant à améliorer le raisonnement pour un meilleur apprentissage. De plus, compte tenu de l’importance des mécanismes émotionnels dans l’apprentissage, nous avons également procédé dans cette partie à la mesure des émotions par des capteurs physiologiques. L’efficacité de notre méthode pour l’apprentissage et son impact positif observé sur les émotions a été validée sur trente et un participants. Dans une seconde partie, nous allons plus loin dans notre recherche en adaptant notre méthode visant à améliorer le raisonnement pour une meilleure induction de la connaissance. L’induction est un type de raisonnement qui permet de construire des règles générales à partir d’exemples spécifiques ou de faits particuliers. Afin de mieux comprendre l’impact de notre méthode sur les processus cognitifs impliqués dans ce type de raisonnement, nous avons eu recours à des capteurs cérébraux pour mesurer l’activité du cerveau des utilisateurs. La validation de notre approche réalisée sur quarante-trois volontaires montre l’efficacité de notre méthode pour l’induction de la connaissance et la viabilité de mesurer le raisonnement par des mesures cérébrales suite à l’application appropriée d’algorithmes de traitement de signal. Suite à ces deux parties, nous clorons la thèse par une discussion applicative en décrivant la mise en place d’un nouveau système tutoriel intelligent intégrant les résultats de nos travaux. / This thesis aims at defining a new learning method to improve knowledge acquisition for intelligent tutoring systems. Learning is a complex phenomenon interlinking both emotional and cognitive mechanisms on conscious and unconscious levels. We are interested in understanding the unconscious mechanisms involved in human reasoning for knowledge acquisition. The importance of these unconscious processes is well documented in neuroscience, but remains largely unexplored in our research field. In this thesis, we put forward a new pedagogical approach in the field of education based on a taxonomy of human perception in neuroscience. We show that this method improves on reasoning which in turn enhances overall learning and inductive capabilities for knowledge acquisition in a problem solving environment. In a first part, we present the implementation of our new method in a tutorial system to improve reasoning hence leading to better learning. Furthermore, acknowledging the importance of emotional mechanisms in learning, we therefore recorded, in this first part, the emotional reactions of users using physiological sensors. The effectiveness of our method for learning and its positive impact on emotions has been validated on 31 participants. In a second part, we go further in our research and enhance our approach in order to improve reasoning for a better induction of knowledge. Induction in a bottom-up logical reasoning approach where one constructs general rules from observed examples. To better understand the impact of our method on the cognitive processes involved in this type of reasoning, we used sensors to record the users’ brain electrical activity. The validation of our approach was carried out on a cohort of 43 volunteers. We showed the effectiveness of our method on the induction of knowledge and sustainability of measuring user’s reasoning by brain recordings after applying proper signal processing algorithms to the data. Following the two parts, we finish the thesis by presenting the implementation of a new intelligent tutoring system incorporating the results found throughout this work.

A Eletroconvulsoterapia (ECT) é o tratamento biológico mais eficaz para quadros depressivos. Os estudos de seus aspectos técnicos são fundamentais tanto para compreensão dos mecanismos da ECT quanto para maximizar a eficácia e minimizar seus efeitos cognitivos. Existem muitos métodos para o cálculo da dose do estímulo elétrico e não há consenso em relação ao melhor. Sabe-se que doses muito elevadas tendem a ser eficazes, mas à custa de efeitos na memória. Embora o método de titulação seja recomendado pela Associação Psiquiátrica Americana, muitos profissionais tem preocupação sobre a segurança cardiovascular deste procedimento, devido aos sucessivos estímulos frustros que levam a um aumento na incidência de bradicardia e/ou assistolia. O objetivo deste trabalho foi traçar o perfil dos pacientes submetidos ao método da titulação do limiar, verificando sua segurança cardiovascular. Para isso foi feito um estudo retrospectivo e 113 casos foram revistos no ano de 2007. A maioria (70,3%) recebeu aplicação bilateral e (62,8%) eram mulheres. O diagnóstico de depressão apareceu com mais freqüência (50,5%). A maioria (57,5%) necessitou de dois estímulos, (12,4%) necessitou de apenas um, (28,3%) necessitou de três e (1,8%) realizou quatro estímulos. A média de frequência cardíaca inicial foi de 79,6 bpm (DP = 17). O limiar convulsígeno variou de 16mC a 128mC (média = 58,9; DP 25,4). A relação do limiar convulsígeno foi significativamente menor com o posicionamento unilateral dos eletrodos (p < 0,001), mas não com sexo ou idade. Não foi encontrada associação com a medicação concomitante. A incidência de bradicardia aumentou com os estímulos frustros, mas não foi significante a relação entre o primeiro e segundo estímulos. Não houve complicações cardíacas significativas e nenhum paciente apresentou assistolia. Conclui-se que o método da titulação do limiar pode ser uma estratégia segura e mais precisa, uma vez que os fatores (sexo, idade e uso de medicamentos) não foram relacionados com o LCT; a baixa incidência de complicações cardiovasculares reforça-o como método de escolha. Não se pode descartar um efeito protetor do uso da atropina. / Electroconvulsive therapy (ECT) is the most effective biological treatment for depression. Studies of the technical aspects are fundamental for understanding the mechanisms of ECT and to maximize efficiency and minimize their cognitive effects. There are many methods to determine the dose of electrical stimulation and there is no consensus on which is the best one. It is known that very high doses are effective, but at the expense of effects on memory. Although the method of limits (titration method) is generally accepted, being encouraged by the American Psychiatric Association, many practitioners have concerns regarding cardiac safety of this method. Due to repetitive subthreshold stimuli until the seizure is elicited, an increased risk of bradiarrhythmia and/or asystole is believed to be present. The objective of this study was to establish the profile of patients undergoing the method of titration of the threshold, checking their cardiovascular safety. A retrospective study was performed including 113 cases that receive their treatment in the year of 2007. The majority (70.3%%) received bilateral ECT, (62.8%) were women. The diagnosis of depression appeared more frequently (50.5%). The majority (57.5%) needed two stimuli; 12.4% needed only one; 28.3% needed three and 1.8% required four stimuli. The average initial heart rate was 79.6 bpm (SD = 17). The seizure threshold ranged from 16mC to 128mC (mean = 58.9, SD 25.4). The ratio seizure threshold was significantly lower with unilateral electrode placement (p <0.001) but not with sex or age. No association was found with concomitant medication. There was an increased incidence of bradycardia with subthreshold stimuli , but there was not a relationship between the first and second stimuli. There were no significant cardiac complications and no patient had asystole. In conclusion, the method of titration of the threshold seems to be a safe and more precise to determined electrical dose, since the factors usually used to predict the threshold (gender, age and medication use) were not related to the LCT The low incidence of cardiovascular complications adds up to its use as the method of choice.. A protective effect of atropine cannot be ruled out.

<p>Strong recent focus on unconscious processes has increased interest in subliminal stimulation and similar experimental technologies. Assumptions about the persistence of effects of unconscious stimulation are generally conservative, referring to seconds or minutes (Silverman, 1977; Velmans, 1991). In Study I, five experiments (<i>N </i>= 365) showed complex effects of unconscious stimulation ten days after subliminal exposure, implying that persistence estimates need reevaluation. Experimental stimuli were "mommy and I are one" (MIO) and "mommy and I are dissimilar" (MIDIS), and neutral control stimuli. Effects consisted of higher correlations between measures pertaining to the self-mother relationship and measures of psychological adjustment. </p><p>These ethically problematic findings prompted investigation in Study II of whether debriefing information to participants could prevent persistent effects of subliminal stimuli, an issue not previously investigated. Two experiments (<i>N</i>=188) tested two kinds of information to participants following subliminal MIDIS or control stimulation. Results showed different persistent effects depending on participant sex. Simple information about the stimulus was effective in preventing these, but elaborate information describing the effects and mechanisms for them was not. The findings have implications for ethical recommendations for subliminal research, and suggest that this unexplored area requires more attention. </p><p>In Study III, a theoretical account for the persistent effects is presented, based on unconscious activation of a relational schema containing goal motivation. Unless the goal is fulfilled or activation dissipates due to attributability or irrelevance of the goal, the activation will be maintained (motivated maintenance). Being unconscious, the influence results in automatic schematic processing of environmental cues, including perceptual, judgment, and behavioral biases. These in turn interactively maintain the activation of the schema (interactive maintenance). </p><p>The discussion includes the conclusion that previous estimates of the persistence of unconscious stimulation effects need revision. Theoretical and empirical questions concerning the studies are discussed and ethical research implications are considered.</p>

Strong recent focus on unconscious processes has increased interest in subliminal stimulation and similar experimental technologies. Assumptions about the persistence of effects of unconscious stimulation are generally conservative, referring to seconds or minutes (Silverman, 1977; Velmans, 1991). In Study I, five experiments (N = 365) showed complex effects of unconscious stimulation ten days after subliminal exposure, implying that persistence estimates need reevaluation. Experimental stimuli were "mommy and I are one" (MIO) and "mommy and I are dissimilar" (MIDIS), and neutral control stimuli. Effects consisted of higher correlations between measures pertaining to the self-mother relationship and measures of psychological adjustment. These ethically problematic findings prompted investigation in Study II of whether debriefing information to participants could prevent persistent effects of subliminal stimuli, an issue not previously investigated. Two experiments (N=188) tested two kinds of information to participants following subliminal MIDIS or control stimulation. Results showed different persistent effects depending on participant sex. Simple information about the stimulus was effective in preventing these, but elaborate information describing the effects and mechanisms for them was not. The findings have implications for ethical recommendations for subliminal research, and suggest that this unexplored area requires more attention. In Study III, a theoretical account for the persistent effects is presented, based on unconscious activation of a relational schema containing goal motivation. Unless the goal is fulfilled or activation dissipates due to attributability or irrelevance of the goal, the activation will be maintained (motivated maintenance). Being unconscious, the influence results in automatic schematic processing of environmental cues, including perceptual, judgment, and behavioral biases. These in turn interactively maintain the activation of the schema (interactive maintenance). The discussion includes the conclusion that previous estimates of the persistence of unconscious stimulation effects need revision. Theoretical and empirical questions concerning the studies are discussed and ethical research implications are considered.

A digital signature technique has evolved into varies digital signature schemes in different application environments. In general, a digital signature consists of a random number and a hash function in addition to signing function. The random number can be used to provide the randomization of digital signatures. The hash function can be used for generating a message digest that has a fix length and is convenient for signing. The random number that hides in the digital signature is a useful factor. If we can use this factor well, then the digital signature can carry the other secret messages. On the basis of the concept of a subliminal channel proposed by Simmon, we have proposed multiple subliminal channels that can carry more than one subliminal message to different subliminal receivers. Furthermore, by using the concept of a subliminal channel, we can use the random number as another secure parameter of the digital signature. This concept leads to a forward-secure digital signature with backward-secure detection when the subliminal channel is embedded in the signature. We have proposed a forward-backward secure digital signature. A hash function is an important tool for generating a message digest. The hash function used in a signature must be one-way and collision resistant. A signing message will map to a message digest via a hash function. In recent years, several chameleon hash functions have been proposed. A chameleon hash function is a trapdoor one-way hash function that prevents everyone except the holder of the trapdoor key from computing the collisions for a randomly given input. There are various studies that apply the chameleon hash function to online/offline digital signatures and sterilization signatures. In this thesis, we apply this concept to a network secure gateway. We have achieved fast blind verification for an application gateway, such as a firewall. Further, we propose triple-trapdoor chameleon hash function and apply to vehicle owenship identification scheme. We have achieved the fast identification for vehicle ownership without connect to online database. We also have proposed threshold chameleon hash function and achieved that the collision will control under the threshold value. The trapdoor information will be exposed after the number of collision has accomplished.

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 &amp;amp; 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 &amp;amp; Hommel, 2001) which state that actions are automatically activated by anticipating their consequences.

Το ηλεκτροεγκεφαλογράφημα αποτελεί μία μέθοδο καταγραφής των ηλεκτρικών σημάτων που παράγονται στο εσωτερικό του εγκεφάλου. Τα ηλεκτρικά αυτά σήματα διαχέονται από το σημείο που παράγονται προς την εξωτερική δερματική επιφάνεια του κρανίου όπου μετρώνται ως διαφορές δυναμικού. Αντικείμενο της διπλωματικής εργασίας είναι η σχεδίαση και η υλοποίηση μίας πειραματικής συνθήκης και της αντίστοιχης πειραματικής διάταξης, η οποία θα επιτρέπει την καταγραφή των Προκλητών δυναμικών του ατόμου που θα εκτελεί το πείραμα. Το κλινικό πρωτόκολλο που χρησιμοποιήθηκε εξετάζει δύο βασικά θέματα. Το πρώτο αφορά την αντίληψη του ανθρώπου για το χρόνο και το δεύτερο το πώς επηρεάζουν τα υποσυνείδητα μηνύματα τη λήψη αποφάσεων και την εγκεφαλική λειτουργία. Αρχικά, στο πρώτο κεφάλαιο της παρούσας διπλωματικής εργασίας, αναφέρονται οι βασικές αρχές του ηλεκτροεγκεφαλογραφήματος και το σύστημα διάδοσης της πληροφορίας στον ανθρώπινο εγκέφαλο. Επιπλέον περιγράφεται ο τρόπος με τον οποίο γίνεται η καταγραφή του σήματος του εγκεφαλογραφήματος και των Προκλητών Δυναμικών. Στη συνέχεια, στο δεύτερο κεφάλαιο παρουσιάζεται η θεωρία στην οποία βασίστηκε ο σχεδιασμός του κλινικού πρωτοκόλλου και η οποία αφορά δύο θέματα, την αντίληψη του ανθρώπου για το χρόνο και την επιρροή των υποσυνείδητων μηνυμάτων στη λήψη αποφάσεων. Στα επόμενα κεφάλαια περιγράφεται το κλινικό πρωτόκολλο που χρησιμοποιήθηκε και οι πειραματικές συνθήκες που εξετάστηκαν κατά τη διεξαγωγή των πειραμάτων. Ακόμα, γίνεται περιγραφή τόσο του υλικού όσο και του λογισμικού μέρους της πειραματικής διάταξης που αναπτύχθηκε για την υλοποίηση του κλινικού πρωτοκόλλου. Η πειραματική διάταξη που αναπτύχθηκε στα πλαίσια της διπλωματικής επιτρέπει τη σύνδεση με Ηλεκτροεγκεφαλογράφο με αποτέλεσμα τον συγχρονισμό της πειραματικής ακολουθίας και της καταγραφής του ηλεκτροεγκεφαλογραφήματος και των Προκλητών Δυναμικών. Με την πειραματική διάταξη που αναπτύχθηκε έγιναν δύο πειράματα. Η καταγραφή της εγκεφαλικής δραστηριότητας του κάθε εξεταζόμενου (ΗΕΓ) ήταν συνεχής για όλη τη διάρκεια της δοκιμασίας. Η εξαγωγή των Προκλητών Δυναμικών έγινε μετά το τέλος της καταγραφής με το πρόγραμμα EEGLAB, με το οποίο έγινε και η επεξεργασία τους. Τα Προκλητά Δυναμικά απεικονίστηκαν τόσο σε δισδιάστατα όσο και σε τρισδιάστατα μοντέλα κεφαλιών ενώ εξετάστηκε και το φασματικό περιεχόμενο του σήματος του ηλετροεγκεφαλογραφήματος για τις διάφορες πειραματικές συνθήκες. Από την ανάλυση των καταγραφών παρατηρήθηκαν κάποιες διαφορές μεταξύ των συνθηκών του πειράματος οι οποίες περιείχαν υποσυνείδητα μηνύματα και αυτών που δεν περιείχαν. Οι κορυφώσεις του δυναμικού εντοπίστηκαν τις ίδιες χρονικές στιγμές για όλες τις συνθήκες ενώ το πλάτος τους ήταν διαφορετικό μεταξύ των συνθηκών στις οποίες δινόταν στους εξεταζόμενους η σωστή απάντηση με υποσυνείδητο μήνυμα και σε αυτές που δεν δινόταν. / The electroencephalogram constitutes a method for recording electrical signals produced in the interior of the brain. These electric signals are diffused from the point of the brain where they are produced to the exterior dermal surface of the skull where they are measured as potential differences. The object of this diploma thesis is the design and the development of an experiment and the corresponding experimental setup, which allows the recording of the Event Related Potentials of the person who executes the experiment. The clinical protocol that is used examines two fundamental issues. The first is related to time perception while the second one examines if and how subliminal messages influence the decision making and the cerebral operation. Initially, in the first chapter of the present diploma thesis, the fundamentals of the Electroencephalogram and the system that is responsible for the distribution of the information inside the human brain is described. Following, Electroencephalogram and Event Related Potentials (ERPs) recordings are described. In the second chapter the theory on which the planning of the clinical protocol was based is presented. It concerns two research fields of psychophysiology; time perception and the influence of subliminal messages in decision-making. In the next chapters the clinical protocol and the experimental conditions that were examined during the experiments are described. Furthermore, there is a description of both the software and the hardware modules of the developed system. The experimental setup that was developed in the framework of the diploma thesis allows the connection to an Electroencephalograph and appropriate trigger signals are used in order to synchronize stimuli and recordings of EEG and ERPs. Two experiments were conducted. The recording of the brain activity was continuous for the whole duration of the experimental procedure. The Event Related Potentials were extracted post-hoc, after the end of the recording, using the EEGLAB software. The Event Relates Potentials were mapped both on two-dimensional and on three-dimensional head models. The spectrum of the electroencephalogram was also examined for the various experimental conditions. Analysis of the recordings revealed differences between the experimental conditions that contained subliminal messages in the EEG and ERPs. The ERPs’ peaks were detected at the same time delays for all the conditions. However, the amplitude of the peaks differed between the conditions where the right answers were given with subliminal messages and those that did not contain any subliminal messages.