A widespread and persistent memory error that people commit on a daily basis is the post-completion error (PCE; i.e., forgetting to complete the final step of a procedural task). PCEs occur in the railroad industry when a locomotive conductor changes the direction of a rail switch but fails to report this change. This particular error could contribute to unsafe conditions as another train traveling on the same track could derail. Although training can help reduce some of the factors leading to unsafe conditions on the rail, research has demonstrated that PCEs are different from other errors of omission in that they cannot be eliminated through training, which makes them a difficult problem to address. Therefore, there is a need to explore new remedial actions designed to reduce PCEs. The current study investigated the effectiveness of a theoretically motivated intervention at reducing PCEs in trainyard operations, where making these errors could be life-threatening. Twenty-eight undergraduates completed trainyard tasks within a high-fidelity simulator. Each participant received the behavioral intervention in one block and no intervention in another. Specifically, participants were required to perform an additional task designed to remind participants of the post-completion (PC) step. The intervention significantly reduced PCE rates in the context of trainyard operations, on average, by 65%. We discuss implications of these results on reducing trainyard accidents, and how this outcome can contribute to the literature on the cause of PCEs.

Infant visual attention develops rapidly over the first year of life, significantly altering the way infants respond to peripheral visual events. Here we present data from 5-, 7- and 10-month-old infants using the Infant Orienting With Attention (IOWA) task, designed to capture developmental changes in visual spatial attention and saccade planning. Results indicate rapid development of spatial attention and visual response competition between 5 and 10 months. We use a dynamic neural field (DNF) model to link behavioral findings to neural population activity, providing a possible mechanistic explanation for observed developmental changes. Together, the behavioral and model simulation results provide new insights into the specific mechanisms that underlie spatial cueing effects, visual competition, and visual interference in infancy.

Die Erforschung visueller Aufmerksamkeit beruht auf verdeckter Aufmerksamkeit; das heißt, wenn der Fokus der Aufmerksamkeit trotz strikter Fixation ausgerichtet wird ohne größere Sakkaden auszuführen. EEG-Studien haben das neuronale Netzwerk identifiziert, dass verdeckte Aufmerksamkeit steuert. Diese Studien ignorieren jedoch unwillkürliche kleine Sakkaden während der Fixation - Mikrosakkaden (MS) genannt. Blickbewegungsstudien hingegen belegen einen Zusammenhang zwischen Aufmerksamkeit und diesen MS, beziehen ihre Resultate jedoch nicht auf etablierte EEG-Befunde. Um diese Forschungslücke zu schließen, zielt diese Dissertation darauf, den Zusammenhang zwischen Ereignis-korrelierten Potentialen (EKP) endogener Aufmerksamkeit und MS zu untersuchen. Folglich wurden drei Studien mit gleichzeitiger Erfassung von EEG und Blickbewegungen durchgeführt. In den Studien haben die Probanden ein „Posner Spatial-Cueing-Paradigma“ absolviert mit einem endogenen Hinweisreiz. Wir zeigen deutliche Zusammenhänge zwischen MS und neuronalen Korrelaten visueller Aufmerksamkeit. Erstens, MS und ein posteriores EKP reflektierten die Selektion visueller Reize basierend auf deren Merkmale. Dieses Ergebnis stärkt die Idee eines Netzwerkes, dass relevante Reize unter Distraktoren selektiert und zielgerichtetes Verhalten initiiert. Zweitens, MS erzeugten ein visuelles Potential, das verstärkte Potentialkomponenten für Reize zeigte, die im Aufmerksamkeitsfokus lagen. Dieses MS-evozierte Potential stellte einen zeitlich gut aufgelösten Aufmerksamkeitsindex dar. Drittens, MS erzeugten zudem ein in früheren Studien übersehenes, korneoretinales Artefakt. Dieses Artefakt kontaminierte die Messung eines frontalen EKPs, dass zuvor mit der Kontrolle von Aufmerksamkeit assoziiert war. Zusammenfassend zeigt diese Dissertation, dass die gleichzeitige Erfassung von EEG und Blickbewegungen bedeutsame Einblicke in den Zusammenhang von MS und visueller Aufmerksamkeit erlaubt. / Research on visual attention focusses on covert attention; that is, when attention is directed during fixation periods in the absence of larger saccades. While previous EEG research has provided insights into the neural network that controls covert attention, this field fails to account for the inevitable occurrence of miniature fixational saccades - called microsaccades (MS). In contrast, previous eye-tracking research has established links between MSs and covert attention, but has not directly related their findings to seminal EEG results. This thesis bridges this research gap by investigating the link between event-related potentials (ERPs) of endogenous attention and MSs. To this end, three studies were conducted with concomitant ERP and high-resolution eye-tracking recordings while participants performed a Posner spatial cueing task with an endogenous cue. Crucially, we show that MSs relate to neural correlates of visual attention. First, MS and an early posterior ERP reflected the top-down selection of a visual stimulus based on its features. This finding is consistent with the notion of a neural network that selects relevant stimuli from distracting ones and initiates goal-directed behavior toward selected stimuli. Second, gaze shifts from MSs evoked a visual potential in the EEG that was enhanced for stimuli in the focus of attention; a finding well-known for the visual potential measured after presenting a stimulus. Importantly, these MS-related potentials provided a fine-grained temporal index of the subject’s attentional state. Finally, MSs further evoked a corneoretinal artifact overlooked in previous EEG studies. This artifact contaminated the measurement of a frontal ERP previously associated with preparatory attentional control. In sum, this thesis provides first evidence for the benefits of using concomitant ERP and eye-tracking recordings to examine the link between MSs and visual attention.

Les environnements virtuels, et en particulier les simulateurs de conduite à plate-forme dynamique, posent la délicate question de la restitution multisensorielle en vue de générer la bonne "illusion" pour leurs utilisateurs. Si la réalité virtuelle est reconnue pour la limitation des coûts, le gain temporel et la contrôlabilité et reproductibilité des situations étudiées, la problématique de la validité de ces outils de recherche (ou de formation) est cruciale pour la transférabilité des connaissances produites.Constituant une première étape dans le processus de validation du simulateur IFSTTAR, ce travail s’appuie sur une démarche originale reposant sur une double évaluation, par élément et globale. Il s’agit (i) de configurer de manière optimale les caractéristiques immersives et interactives du simulateur liées au mouvement de roulis afin de produire une illusion d’inclinaison crédible et acceptée, et (ii) d’évaluer, de manière globale, différentes configurations du simulateur (modèles dynamiques de véhicule) au moyen de mesures objectives (temps de familiarisation) et subjectives (présence, mal du simulateur).Prises dans leur ensemble, les sept études menées durant cette thèse ont permis de valider une plage de restitution du mouvement de roulis pertinente pour produire une sensation d’inclinaison sans entraîner de déséquilibre critique ou de sensation de chute. Un angle d’inclinaison du simulateur au-delà de 11,4 degrés est ainsi déconseillé pour éviter toute sensation de chute, néanmoins cette valeur est susceptible d’être influencée par divers facteurs (e.g., présence d’informations visuelles, positionnement de l’axe de roulis). Ces études ont également permis d’identifier, en conduite passive, les paramètres nécessaires ainsi que les contributions relatives des informations visuelle et inertielle pour la production d’une sensation d’inclinaison crédible. En conduite active, l’évaluation du degré de contrôle des participants en fonction du modèle dynamique de véhicule (virtuel) a permis de pointer les faiblesses actuelles du simulateur IFSTTAR afin de proposer plusieurs pistes de développement. / Virtual environments, and specifically motion-based driving simulators, raise the delicate question of multisensory cueing in order to produce the good "illusion" to the users. If virtual reality is well acknowledged for cost limitation, validity issue of these research (or training) tools is critical for knowledge transfer of new results.As a first step in the validation process of the IFSTTAR motorcycle simulator, this work relies upon an original design based on a double approach : by element and global. It consists in (i) optimal balancing of simulator’s immersive and interactive characteristics linked to roll motion so as to yield a believable and embraced leaning illusion, and (ii) evaluating more generally different simulator configurations (vehicle dynamic models) through objective (training length) and subjective measures (presence, simulator sickness).Taken as a whole, the seven studies conducted during this thesis enable the validation of the relevant range of roll motion cueing to produce a leaning sensation without leading to a critical unbalance or fall sensation. A leaning angle of the simulator beyond 11.4 degrees is not recommended to avoid any fall sensation, however this figure can be influenced by various factors (e.g., visual informations, roll axis location). These studies also allow to identify, in passive driving situations, the necessary parameters as well as the relative contribution of visual and inertial informations for the production of a believable leaning sensation. In an active driving situation, the evaluation of the degree of users control through different (virtual) vehicles dynamic models has permitted to highlight the weaknesses of IFSTTAR simulator in order to set several guidelines for further development.

This qualitative study examines an asynchronous online course from a private university utilizing a template model for all online courses to provide students with consistent navigation and course structure throughout their degree program. The asynchronous online courses are purposely created using three criteria of quality course design: navigation is intuitive, information is chunked, and instructions are written clearly. A two-part usability test was conducted with three internal and three external participants. The two-part usability test focused on course navigation and examined the signaling, segmenting, and coherence principles applied to course content page layouts. Transcripts from the usability tests and observational field notes were coded through an iterative process in Nvivo. Through emic and etic coding, seven main categories were identified: user experience, cognitive load, multimedia learning principles, page design and layout attributes, course navigational attributes, course attributes and information, and participant navigational behavior. The findings for first-day navigation, general navigational behaviors, and perceptions of design elements used to implement the signaling, segmenting, and coherence principle are discussed. Course design recommendations for creating a positive usability experience and suggestions for future research are provided.

Les patients schizophrènes souffrent de graves déficits de mémoire autobiographique. Cela a un impact direct sur leur identité personnelle et leur statut fonctionnel dans la vie quotidienne. A travers 3 études, nous avons montré que l’ensemble des caractéristiques subjectives du rappel des souvenirs est perturbé chez les patients schizophrènes (distorsion de la perception du temps subjectif, moindre fréquence de la perspective visuelle Acteur). L’altération de ces aspects subjectifs serait liée au manque de spécificité et de détails des souvenirs. Ce sont ces détails qui rendent le rappel des souvenirs vivace. Aussi, nous avons testé l’efficacité d’une méthode qui a montré que les déficits de récupération stratégique de ces détails pouvaient être corrigés. Les patients sont capables d’améliorer le rappel des détails de leurs souvenirs si une aide appropriée leur est fournie. Une thérapie de remédiation cognitive basée sur cette méthode pourrait être proposée aux patients schizophrènes. / Patients with schizophrenia suffer from severe autobiographical memory deficits. These have a significant impact on patients’ personal identity and functional status in daily life. Through three studies, we showed that all the subjective characteristics of autobiographical recall are impaired in patients with schizophrenia (distorted perception of subjective time, memory recall less associated with Field visual perspective). The impairment of these subjective aspects of autobiographical recall was linked to the lack of specificity of memories and low level of details in patients’ memories. It is these details which allow vivid memory recall. Hence, we tested the effectiveness of a method which showed that deficits in the strategic retrieval of memory details could be remediated. Patients are able to improve the recall of their memory details when given the necessary means to do so. A cognitive remediation therapy, based on this method, could be set up with patients with schizophrenia.

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Gaze is an important social signal in interactions between humans, but also in interactions between humans and artificial agents such as robots, autonomous vehicles, or even avatars presented via displays. It can help to recognize to which persons or objects the interaction partners direct their attention and to infer their intentions to act. By consciously directing the gaze, it is possible to point to a specific position. In many works, arrows are used as learned, artificial directional cues for comparison with gaze cues. Three studies on different aspects of gaze perception form the core of this thesis. Study 1 deals with the estimation of gaze target positions in videoconferencing settings. For this purpose, pictures of persons ('senders' of gaze) who looked at certain positions on a screen were shown. The task of the subjects ('receivers' of the gaze) was to estimate these positions and mark them on their own screen by mouse click. The results show that the precision of such estimates is greater in the horizontal direction than in the vertical direction. Furthermore, a bias of the estimates in the direction of the senders' face or eyes was found. Studies 2 and 3 investigated the influence of cues on visual attention control using a so-called spatial cueing paradigm. After the appearance of a central cue, the participants' task was to respond to target stimuli away from the center of the screen by pressing keys. Whether the cue direction predicted the target position depended on the condition. In Study 2, schematic faces were compared with arrows. Data obtained when cues were used that always pointed in the opposite direction of the target, suggests that the direction of action of arrows is more easily overridden than that of gaze directions. A dynamic, geometric cue stimulus was investigated in Study 3. Here, a blue disc with two red lines moving from the center to the side served as a cue. This abstract stimulus resulted in a reaction time advantage in the direction of movement of the lines. After several trials, videos were shown in which a human avatar wearing a blue helmet, also with red lines, was shown from behind. When he looked sideways and turned his head, the lines moved in the opposite direction to his gaze. This was intended to elicit an alternative interpretation of the abstract cue as the back of the helmet. The results show a partial reduction of the initial effect of the abstract cue. This suggests that stimuli that do not resemble eyes can be learned as gaze and used as cues. In context of human-machine interactions the three studies provide fundamental insights into the human ability to estimate gaze orientation and the effect of gaze cues, which are particularly relevant for the design of gaze displays.:Contents Bibliographische Beschreibung Zusammenfassung 1 Introduction 1 1.1 Gaze as social cue 2 1.1.1 Joint attention 2 1.1.2 Biological and evolutionary perspective 3 1.1.3 Reflective and volitional processes 3 1.2 Cueing paradigms 4 1.2.1 Arrows predicting target position 5 1.2.2 Schematic faces that look only randomly in the direction of the target 5 1.3 Human gaze 6 1.3.1 Attention orientation and eye movements 6 1.3.2 Visual sensors in humans 6 1.4 Artificial gaze 8 1.4.1 Stationary displays 8 1.4.2 Precision of gaze direction estimation 9 1.4.3 Sensor types 9 1.4.4 Gaze of robots and mobile vehicles 10 1.5 Gaze as a communicative sensor system 11 1.6 Goals of the thesis 12 2 Summary of individual studies 14 2.1 Study 1: Gaze estimation in videoconferencing settings 14 2.2 Study 2: Attentional cueing: gaze is harder to override than arrows 15 2.3 Study 3: Effects of Interpreting a Dynamic Geometric Cue as Gaze on Attention Allocation 17 3 Discussion 19 3.1 Performance of gaze orientation estimates 19 3.2 Social cues 20 3.3 Sensor-display linkage 21 3.4 Future Perspectives 23 3.4.1 Receivers’ eye movements 23 3.4.2 Gaze in complex and interactive settings 24 3.4.3 Spatial cueing paradigm in product development 25 3.5 Conclusions 26 4 References 28 5 Appendix 36 Author’s Contributions 36 Gaze estimation in videoconferencing settings 37 Attentional cueing: gaze is harder to override than arrows 76 Accuracy 90 Cue Type 90 Cueing 90 Cue Type : Cueing 90 Effects of Interpreting a Dynamic Geometric Cue as Gaze on Attention Allocation 107 Danksagungen 130 / Blicke sind wichtige soziale Signale in Interaktionen zwischen Menschen, aber auch in Interaktionen zwischen Menschen und künstlichen Agenten wie Robotern, autonomen Fahrzeugen oder auch Avataren, die über Displays präsentiert werden. Sie können helfen zu erkennen, auf welche Personen oder Objekte die Interaktionspartner:innen ihre Aufmerksamkeit richten und auf deren Handlungsabsichten zu schließen. Durch bewusste Blickausrichtung kann gezielt in eine Richtung oder auf eine Position gezeigt werden. In vielen Arbeiten werden Pfeile als erlernte, künstliche Richtungshinweise zum Vergleich mit Blickhinweisen verwendet. Den Kern dieser Arbeit bilden drei Studien, die jeweils unterschiedliche Aspekte der Blickwahrnehmung untersuchen. Studie 1 beschäftigt sich mit der Schätzung von Blickzielpositionen in Videokonferenzsituationen. Dazu wurden Bilder von Personen ('Sender' der Blicke) gezeigt, die auf bestimmte Positionen auf einem Bildschirm blickten. Die Aufgabe der Versuchspersonen ('Empfänger' der Blicke) bestand darin, diese Positionen zu schätzen und auf dem eigenen Bildschirm per Mausklick zu markieren. Die Ergebnisse zeigen, dass die Präzision solcher Schätzungen in horizontaler Richtung größer ist als in vertikaler Richtung. Außerdem wurde eine Verzerrung der Schätzungen in Richtung des Gesichtes bzw. der Augen der Sender festgestellt. Studien 2 und 3 untersuchten den Einfluss von Hinweisreizen auf die visuelle Aufmerksamkeitslenkung mittels eines sogenannten Spatial Cueing Paradigmas. Die Aufgabe der Versuchspersonen bestand darin, nach dem Erscheinen eines Hinweisreizes in der Bildschirmmitte, der je nach Experiment und Bedingung in die Richtung des Zielreizes zeigte oder nicht, durch Tastendruck auf Zielreize neben der Bildschirmmitte zu reagieren. In Studie 2 wurden schematische Gesichter mit Pfeilen verglichen. Ergebnisse für Hinweisreize, die immer in die entgegengesetzte Richtung des Zielreizes zeigten, deuten darauf hin, dass die Wirkrichtung von Pfeilen leichter überschrieben werden kann als die von Blickrichtungen. Ein dynamischer, geometrischer Hinweisreiz wurde in Studie 3 untersucht. Hier diente eine blaue Scheibe mit zwei roten Linien, die sich von der Mitte zur Seite bewegten als Hinweisreiz. Dieser abstrakte Reiz führte zu einem Reaktionszeitvorteil in der Bewegungsrichtung der Linien. Nach einigen Durchgängen wurden Videos gezeigt, in denen ein menschlicher Avatar einen blauen Helm mit ebenfalls roten Linien trug. Der Avatar wurde von hinten gezeigt und wenn er seinen Blick zur Seite richtete und dazu den Kopf drehte, bewegten sich die Linien entgegen der Blickrichtung. Auf diese Weise sollte eine alternative Interpretation des abstrakten Hinweisreizes als Helmrückseite induziert werden. Die Ergebnisse zeigen eine teilweise Reduktion des ursprünglichen Effektes des abstrakten Hinweisreizes, was auf eine Wirkung der Induktionsvideos entgegen der ursprünglichen Wirkrichtung schließen lässt. Das weist darauf hin, dass auch Stimuli als Blicke gelernt und so als Hinweisreiz genutzt werden können, die keine Ähnlichkeit mit Augen haben. Eingebettet in den Kontext von Mensch-Maschine-Interaktionen, liefern die drei Studien grundlegende Erkenntnisse zur menschlichen Fähigkeit Blickausrichtung zu schätzen und der Wirkung von Blicken als Hinweisreize, die insbesondere für die Gestaltung von Blickdisplays relevant sind.:Contents Bibliographische Beschreibung Zusammenfassung 1 Introduction 1 1.1 Gaze as social cue 2 1.1.1 Joint attention 2 1.1.2 Biological and evolutionary perspective 3 1.1.3 Reflective and volitional processes 3 1.2 Cueing paradigms 4 1.2.1 Arrows predicting target position 5 1.2.2 Schematic faces that look only randomly in the direction of the target 5 1.3 Human gaze 6 1.3.1 Attention orientation and eye movements 6 1.3.2 Visual sensors in humans 6 1.4 Artificial gaze 8 1.4.1 Stationary displays 8 1.4.2 Precision of gaze direction estimation 9 1.4.3 Sensor types 9 1.4.4 Gaze of robots and mobile vehicles 10 1.5 Gaze as a communicative sensor system 11 1.6 Goals of the thesis 12 2 Summary of individual studies 14 2.1 Study 1: Gaze estimation in videoconferencing settings 14 2.2 Study 2: Attentional cueing: gaze is harder to override than arrows 15 2.3 Study 3: Effects of Interpreting a Dynamic Geometric Cue as Gaze on Attention Allocation 17 3 Discussion 19 3.1 Performance of gaze orientation estimates 19 3.2 Social cues 20 3.3 Sensor-display linkage 21 3.4 Future Perspectives 23 3.4.1 Receivers’ eye movements 23 3.4.2 Gaze in complex and interactive settings 24 3.4.3 Spatial cueing paradigm in product development 25 3.5 Conclusions 26 4 References 28 5 Appendix 36 Author’s Contributions 36 Gaze estimation in videoconferencing settings 37 Attentional cueing: gaze is harder to override than arrows 76 Accuracy 90 Cue Type 90 Cueing 90 Cue Type : Cueing 90 Effects of Interpreting a Dynamic Geometric Cue as Gaze on Attention Allocation 107 Danksagungen 130

Durant l'envelliment es dónen canvis estructurals i funcionals al cervell, especialment a l'escorça prefrontal, un dels substractes anatòmics responsables del control atencional. Aquest es va mesurar emprant tècniques neuropsicològioques i neurofuncionals durant l'execució de tasques de canvi amb senyals implícites (tipus WCST). 80 subjectes majors sans es varen dividir segons la seva edat i el seu nivell de control cognitiu. El baix control cognitiu (però no l'edat) s'associà a un augment dels costos residuals de resposta, en paral.lel amb una major amplitud del component P2 davant els senyals. L'edad avançada, en conjunt amb un baix nivell de control s'associà a un increment dels costos locals de resposta durant el canvi de tasca, paral.lelament amb l'augment de les ones lentes durant la fase de senyalització. Mantenir dues tasques en memòria es més difícil per als subectes amb baix control, reflexat per una reducció en l'amplitud de les ones lentes fronto-parietals

Carefree handling refers to the ability of a pilot to operate an aircraft without the need to continuously monitor aircraft operating limits. At the heart of all carefree handling or maneuvering systems, also referred to as envelope protection systems, are algorithms and methods for predicting future limit violations. Recently, envelope protection methods that have gained more acceptance, translate limit proximity information to its equivalent in the control channel. Envelope protection algorithms either use very small prediction horizon or are static methods with no capability to adapt to changes in system configurations. Adaptive approaches maximizing prediction horizon such as dynamic trim, are only applicable to steady-state-response critical limit parameters. In this thesis, a new adaptive envelope protection method is developed that is applicable to steady-state and transient response critical limit parameters. The approach is based upon devising the most aggressive optimal control profile to the limit boundary and using it to compute control limits. Pilot-in-the-loop evaluations of the proposed approach are conducted at the Georgia Tech Carefree Maneuver lab for transient longitudinal hub moment limit protection. Carefree maneuvering is the dual of carefree handling in the realm of autonomous Uninhabited Aerial Vehicles (UAVs). Designing a flight control system to fully and effectively utilize the operational flight envelope is very difficult. With the increasing role and demands for extreme maneuverability there is a need for developing envelope protection methods for autonomous UAVs. In this thesis, a full-authority automatic envelope protection method is proposed for limit protection in UAVs. The approach uses adaptive estimate of limit parameter dynamics and finite-time horizon predictions to detect impending limit boundary violations. Limit violations are prevented by treating the limit boundary as an obstacle and by correcting nominal control/command inputs to track a limit parameter safe-response profile near the limit boundary. The method is evaluated using software-in-the-loop and flight evaluations on the Georgia Tech unmanned rotorcraft platform- GTMax. The thesis also develops and evaluates an extension for calculating control margins based on restricting limit parameter response aggressiveness near the limit boundary.