The experiments reported in this thesis were conducted to examine the effects of executive-control and associative-learning processes on performance in conventional executive-control paradigms. For this purpose, I developed comparative task-switching and response-inhibition paradigms, which were used to assess the performance of pigeons, whose behaviour is presumably based purely on associative processes, and of humans, whose behaviour may be guided by executive control and by associative processes. Pigeons were able to perform accurately in the comparative paradigms; hence, associative-learning processes are sufficient to account for successful performance. However, some task-specific effects that can be attributed to executive-control processes, and which were found in humans applying executive control, were absent or greatly reduced in pigeons. Those effects either reflect the mental operations that are performed to ensure that a specific set of stimulus-response-contingencies is applied and any contingencies belonging to a different set are suppressed, or reflect mental preparations for the possibility that the requirement to execute a certain response suddenly changes. In particular, in Chapter 3, it is shown that the benefits of repeatedly applying the same set of stimulus-response contingencies (or, in reverse, the costs of switching from one set to another) do not apply when Pavlovian processes dominate learning, which is likely the case for pigeons. Furthermore, as shown in Chapters 4 and 5, the behavioural effects of preparing for an unpredicted change in response requirements appeared to be absent when behaviour was based purely on associative processes. Instead, associatively mediated performance was primarily influenced by the stimulus-response contingencies that were effective in each paradigm. Repeating the same response in consecutive trials facilitated the performance of pigeons and associatively learning human participants in the task-switching paradigms, and performing a particular Go response increased the pigeons' likelihood of executing that response in the following trial in two response-inhibition paradigms. In summary, any behavioural effects that can be observed at the level of abstract task requirements reflect the influence of executive-control processes, both in task-switching paradigms and in response-inhibition paradigms.

Experiencing maltreatment during childhood has been implicated in numerous and diverse developmental impairments, including problematic alcohol use and alcohol use disorders. However, little research examines the processes by which childhood maltreatment confers risk for alcohol use problems, or potential risk or protective factors in the emergence of problematic alcohol use among individuals experiencing childhood maltreatment. To address this gap, the current study investigated executive cognitive functions and emotion regulation as probable risk or protective factors linking childhood maltreatment and subsequent problematic alcohol use, given that deficits in both executive cognitive functions and emotion regulation are associated with maltreatment and problematic alcohol use. Participants were drawn from a longitudinal sample of children at both high and low risk for substance dependence, based on their paternal history of psychiatric or substance use disorder (N = 475; 70% male; 74% Caucasian, 23% African American, 3% multiracial; M = 11.38±.93 years at Time 1). Analyses involved both person- and variable-centered approaches. The person-centered approach identified groups of individuals based on maltreatment experiences, executive cognitive functions, and emotion regulation, and then examined whether and to what extent these classes differed on concurrent and longitudinal problematic alcohol use. Findings suggested that there are distinct risk groups consisting of abuse/neglect, neglect only, executive control function deficits, and emotion regulation deficits. These groups did not differ on levels of alcohol use, counter to prediction. Variable-centered approaches involved a longitudinal examination of pathways from childhood maltreatment to alcohol use frequency and symptoms of alcohol use disorder that included executive cognitive functioning and emotion regulation. Results of these variable-centered structural equation modeling analyses indicated that maltreatment, executive control function, and emotion regulation concurrently predicted problematic alcohol use. Investigating the current models allows for a better understanding of pathways to alcohol use in both adolescence and adulthood, which has implications for prevention and intervention, particularly in identifying groups at highest risk for problematic alcohol use outcomes and in treatment selection or modification. / Psychology

The use of biomarkers in Alzheimer’s disease (AD) has been fundamental for early diagnosis. Currently, biomarkers in use for clinical purposes assess the presence or quantify molecular markers of the disease, i.e., ß-amyloid or Tau protein, or quantify the medial-temporal atrophy caused by the disease. Neuroimaging techniques such as structural, functional and diffusion magnetic resonance imaging and positron-emission tomography have been essential in showing how Alzheimer’s disease pathology spreads within resting-state networks, ultimately impairing their functioning. However, neuroimaging techniques provide indirect measures that do not capture the physiological status of the affected cerebral tissues. Neurophysiological techniques, such as transcranial magnetic stimulation (TMS) and electroencephalography (EEG), are established techniques that can be used in combination to capture both the status of a target cortex and its connections through the brain through TMS-evoked potentials (TEPs). Therefore, TEPs have gained momentum as a possible novel AD biomarker. In the last decade, a specific five-phase framework for the development of novel AD biomarkers has been developed, with the goal of standardizing the steps needed to bring a measure from research to clinical practice. Phase 1 for TEPs, concerning the rationale of using them as a biomarker in AD, could be considered completed, while most of the research is now focusing on phase 2. In this phase, the ability of a measure to distinguish between healthy elderly individuals and AD patients is assessed, together with the reliability and replicability of the measure. In this thesis, we address several aims of phase 2 by testing whether early TEP responses could be used to differentiate between healthy elderly, prodromal, late-onset, and early-onset AD. Then, we test the sensitivity of TEPs to different preprocessing pipelines to assess their robustness. Third, we review the current literature on TEP reliability and describe which tests are missing for this measure to enter clinical practice. Finally, we propose a tool to promote replicability in noninvasive brain stimulation paradigms, such as TMS–EEG. We conclude that despite a solid rationale for the employment of TEPs in clinical practice, several methodological issues need to be addressed before TEPs can gain clinical utility.

Les fonctions exécutives (FE) sont définies comme des processus de contrôle permettant d'adapter les comportements dans des situations nouvelles. La littérature sur l'homme fait état de fortes variabilités interindividuelles dans l'exécution de ces FE, notamment liées à l'âge des individus. Dans une approche comparative, nous avons cherché à savoir si le primate non humain exprimait de telles variabilités interindividuelles, dans quelle mesure, et pour quelle(s) fonctions(s). Nous avons proposé une série de tâches à un groupe de babouins Papio papio où des individus mâles et femelles d'âges différents, et de statuts sociaux différents cohabitent. Ces expériences ont bénéficié de l'environnement exceptionnel de la plateforme de Comportement et Cognition du Primate située sur la station de Primatologie CNRS de Rousset, où un groupe de babouins a accès ad libitum à dix systèmes de conditionnement opérant automatisés. Les tâches proposées impliquaient chacune une FE particulière, notamment les fonctions d'inhibition et de flexibilité cognitive. Les procédures utilisées, qui reposent sur un principe de conditionnement opérant, consistaient à présenter les tâches sur des écrans tactiles sur lesquels les babouins devaient donner leur réponse. Les expériences impliquant principalement l'inhibition ont montré que le babouin est capable de mettre en place un contrôle inhibiteur efficace. Cependant, les individus les plus âgés montrent des déficits dans leurs performances. Au contraire, lorsque la tâche d'inhibition a une forte composante motrice, les jeunes ont plus de difficultés à adapter leur mouvement. / Executive functions (EF), which are defined as control processes, serve the adaptation of the behaviour in new situations. The human literature reveals important inter-individual variabilities in the efficiency of EF, in particular when age is considered. In a comparative perspective, we investigated if similar individual differences also exist in nonhuman primates, and for which function(s). Several tasks were thus proposed to a group of baboons Papio papio, comprising individuals of both sexes and different ages and social status. These experiments were run in a unique research facility, the Primate Behaviour and Cognition platform (Primatology center, Rousset-sur-Arc), where the baboons had an ad libitum free access to ten automated operant conditioning test systems equipped with touch screens. Each task targeted a particular EF, including the functions of inhibition and cognitive flexibility. The baboons demonstrated an efficient inhibitory control in our tasks. Overall, older individuals showed deficits in inhibitory control when compared to the younger subjects. However, this pattern of results is inverted when motor rather than cognitive inhibition was required. The second set of experiments studied cognitive flexibility. That EF appears deficient in adults, in comparison to the younger individuals. Thus, as in humans, monkeys show significant individual differences in executive control. It is concluded that their analysis requires to distinguish motor from cognitive inhibition, and to pay special attention to the factor of age.

La gestion des buts, définie comme la capacité à se représenter les buts et à les maintenir activement en mémoire de travail, jouerait un rôle central dans l'efficience du contrôle exécutif. Cette thèse vise à étudier l'évolution de cette composante au cours de différents âges de la vie, ainsi que l'influence de verbalisations imposées sur ce développement. Quatre études ont été conduites et ont révélé 1) que l'amélioration de la capacité à gérer les buts lors de la période préscolaire s'accompagnait d'une évolution qualitative du contrôle; 2) que l'évolution des performances en flexibilité de l'enfance au grand âge était spécifiquement liée au développement de la gestion des buts ; et 3) que les verbalisations imposées modulaient le développement de la gestion des buts en produisant un bénéfice plus marqué chez les enfants et les adultes âgés. L'engagement d'un contrôle anticipé, proactif, lors de tâches d'alternance semble favorisé par l'emploi spontané de stratégies visant à orienter l'attention vers le but de la tâche, à la fois pour récupérer précocement la représentation du but, et pour la maintenir activement en mémoire lors des étapes de traitement de la tâche. L'effet bénéfique de verbalisations imposées chez les enfants et les adultes âgés suggère que ces populations présentent des difficultés à gérer les buts lorsqu'ils doivent effectuer la tâche en silence. Ces difficultés proviendraient d'une immaturité ou d'un déficit du langage interne, ou du fait qu'ils ne comprennent pas l'importance de s'engager dans une préparation anticipée de la tâche, ou encore qu'ils n'ont pas conscience que le recours au langage peut être bénéfique pour effectuer la tâche. / Goal-setting, defined as the ability to represent and maintain task goals in working memory, play a crucial role in executive control. The current work aims to study how this component develops across different age groups. It also examines whether required verbalizations have an impact on this development. To this end, four experimental studies were conducted, and revealed 1) that improvement in goal-setting ability during preschool years was associated with qualitative changes in the control used; 2) that flexibility abilities from childhood to old age was specifically linked to the development of goal-setting component; and 3) that requested verbalizations influenced the development of goal-setting ability by producing benefits in children and older adults. The use of proactive control in task-switching could be promoted by the spontaneous utilization of strategies which enable attention reorientation toward task goals to retrieve goal representation and to maintain it in memory during the processing steps of the task. The beneficial effect of requested verbalizations in children and older adults suggests that these age groups encounter goal-setting difficulties when asked to perform the task in silence. Such difficulties may stem from immaturity or deficits in inner speech, from the fact that these age groups do not understand the necessity to engage in an advance preparation of the task, or from their lack of awareness of the benefits induced by verbal strategies.

Eines der ungelösten Probleme menschlicher Kognition ist S. Monsell (1996) zufolge, wie genau sprachliche Aufgabeninstruktionen in Aufgabenrepräsentationen übersetzt werden, die instruiertes Verhalten steuern. Die vorliegende Arbeit versucht, Licht auf einen Aspekt dieser Frage zu werfen. Die spezifische Frage ist, ob und wie die Details der Instruktionen von Antworten in einfachen manuellen Zweifachwahlaufgaben die Kodierung und die Prozesse beeinflussen, die üblicherweise mit "Antwortselektion" assoziiert werden, einem Verarbeitungsstadium, das als zentral für die willkürliche Steuerung von Handlungen angesehen wird. Thematisch liefert die Dissertation somit einen Beitrag zu der Frage nach den kognitiven Grundlagen der Steuerung von Willkürhandlungen. Unter der Annahme, dass die spezifischen Inhalte sprachlicher Antwortinstruktionen die Antwortkodierung determinieren, ist zu erwarten, dass identische Aufgaben bei unterschiedlicher Antwortinstruktion unterschiedlich bearbeitet werden. Diese Vorhersage wurde mittels zweier experimenteller Ansätze in fünf Experimenten überprüft, in denen linke und rechte Tastendruck-Reaktionen entweder räumlich (als "linke" vs. "rechte" Taste) oder farblich (als "blaue" vs. "grüne" Taste) instruiert wurden. Es wurde untersucht, welchen Einfluss Antwortinstruktionen auf zwei Arten von Kompatibilitätseffekten haben. In den ersten 3 Experimenten wurde ein Doppelaufgabenparadigma gewählt, das überlappende vs. nicht-überlappende Antworten auf einer manuellen und einer zeitgleich ausgeführten verbalen Aufgabe erforderte. Die verbale Aufgabe erforderte ebenfalls entweder "links"- und "rechts"- oder "blau"- und "grün"-Antworten. Wenn die Antworten beider Aufgaben räumlich (Experiment 1) oder farblich (Experiment 2) instruiert wurden, waren kompatible Antworten (z. B. verbale "blau"-Reaktionen gefolgt von blauen Tastenreaktionen) in beiden Aufgaben schneller als inkompatible. Wenn jedoch die verbale Aufgabe "links"- und "rechts"-Reaktionen verlangte, während die Tasten der manuellen Aufgabe farblich instruiert wurden, zeigten sich keine Kompatibilitätseffekte. Das 4. und 5. Experiment dieser Arbeit erweitern die Doppelaufgabenexperimente dahingehend, dass der Einfluss der gleichen Antwortinstruktionsmanipulation auf den "Simon-Effekt" (schnellere Antworten bei Korrespondenz als bei Inkorrespondenz zwischen Antwortposition und irrelevanter Stimulus-Position) mit Hilfe einer Aufgabe untersucht wurde, in der linke und rechte Tastenreaktionen willkürlich zentral dargebotenen Stimuli (Buchstabenidentität) zugeordnet wurden. Go/no-go Signale, die zufällig an unterschiedlichen Positionen erschienen, gaben an, ob reagiert werden sollte oder nicht. Während ein Simon-Effekt bei räumlicher Antwortinstruktion in Experiment 4 beobachtet werden konnte, führten Farbinstruktionen der Antworttasten in Experiment 5 zu einer signifikanten Reduktion des Effekts. Zusammengenommen legen diese Ergebnisse nahe, dass die in der Antwortinstruktion genutzten Antwort-"Label" direkt bestimmen, welche Codes zur Reaktionssteuerung genutzt werden, und dass nicht-räumliche Antwortkodierung bei nicht-räumlicher Antwortinstruktion dominiert. Die Implikationen der Befunde für aktuelle Kodierungstheorien zur Erklärung von Kompatibilitätseffekten werden diskutiert und in Bezug gesetzt zu allgemeineren Theorien und Fragen zur willkürlichen Steuerung von Verhalten und zu den Bedingungen von Automatizität. / According to Monsell (1996), one of the 'unsolved mysteries of mind' is how exactly verbal task instructions are translated into, and are used to control behavior. The present dissertation attempts to shed some light on one aspect of this mystery, namely on how the wording of task instructions affects the codes and processes commonly associated with response selection, a processing 'stage' assumed to be central in action control. The main question is whether or not the response labels used in the instructions of manual two-choice responses affect how responses are coded and accessed. If instruction determines response coding, then it should be possible to demonstrate that identical tasks are performed differently if response instructions differ. In five experiments, I manipulated response instructions for spatially organized keypress responses. Specifically, I instructed left and right keypresses on a manual task either as left vs. right or as blue vs. green keypresses and tested whether such variations in response instructions affect two different types of compatibility effects. The first set of experiments (Experiments 1-3) used a dual task procedure that, in addition to the manual task, required either "left" vs. "right" or "blue" vs. "green" verbalizations on a concurrently performed verbal task. When responses on both the manual and the verbal task were instructed in terms of location (Experiment 1) or color (Experiment 2), then compatible responses on the two tasks (e.g., "blue" verbalizations followed by a blue keypress) were faster than incompatible responses. However, when the verbal task required "left" vs. "right" responses whereas manual keypresses were instructed as blue vs. green (Experiment 3), then no compatibility effects were observed. The second set of experiments (Experiments 4 and 5) extended these findings by employing the same response-instruction logic to a Simon-like task, in which left and right keypress responses were arbitrarily mapped to centrally presented stimuli (letter identity). Go/No-go signals that varied in location indicated whether the prepared response was to be executed or not. Color instructions of the response keys (Experiment 5) significantly reduced the Simon effect (i.e., faster responses when response location and irrelevant Go/No-go location correspond) observed under spatial response instructions (Experiment 4). Taken together, these results suggest that response labels used in the instruction directly determine the codes that are used to control responding, and that non-spatial coding can override spatial coding under non-spatial response instructions. The findings are discussed with respect to their relevance for contemporary coding accounts of compatibility and more general theories of intentional control and automaticity.

Les nombreuses études ayant porté sur le vieillissement cognitif ont très tôt permis de distinguer deux composantes clés de la cognition : une composante de « connaissances » définie comme l’ensemble des connaissances générales acquises tout au long de la vie, et une composante de « contrôle exécutif», défini comme l’ensemble des processus de contrôle et de régulation de l’action. Ces modèles permettent d’avancer l’idée selon laquelle le recours à ces deux composantes évolue de manière différentielle au cours de la vie. De ce fait, l’objectif de ce travail de thèse était d’examiner l’implication de ces deux composantes dans la cognition à différentes périodes de vie mais également de déterminer si l’une ou l’autre de ces composantes pouvaient jouer un rôle de protection contre le vieillissement cognitif. L’ensemble des résultats de ce travail suggère que la composante de « contrôle » serait impliquée de manière particulièrement importante dans la cognition chez les adultes âgés, et que cette même composante pourrait jouer un rôle de modération du fonctionnement cognitif au cours du vieillissement normal / Several studies of cognitive aging allow to distinguish two key components of the cognition: « knowledge » defined as the general knowledge acquired throughout the life, and the « executive control », defined as the set of operations that control and regulate cognitive performance. These models suggest that the recourse to these two components evolves in a differential way during the life. Therefore, the objective of this work was to examine the implication of these two components in the cognition at different periods of life but also to determine whether one or the other of these components could play a protective role against the cognitive aging. Results suggest mainly that « control » is more involved in the cognition in older adults, and that this component moderates age-related effect on cognitive functioning

Ziel der vorliegenden Arbeit war es, mittels des Aufgabenwechselparadigmas, kognitive Prozesse nicht nur anhand von traditionellen Leistungsparametern, sondern zusätzlich durch elektro-physiologische Parameter zu untersuchen. Parameter ereigniskorrelierter Hirnpotentiale (EKP) wurden ebenfalls zur Einschätzung von altersbedingten Änderungen bei der Ausführung von Reaktionszeitaufgaben herangezogen.<br> Nach Rubinstein et al. (2001) setzt sich die Reaktionszeit aus der Dauer seriell angeordneter Verarbeitungsstufen zusammen. Im Stufenmodell der exekutiven Kontrolle von Rubinstein et al. (2001) sind Prozesse der ausführenden Kontrolle nur an Wechseltrials beteiligt und können getrennt von den Aufgabenprozessen ablaufen. Mittels der Informationen zu den Reaktionszeiten ist es jedoch nicht möglich zu klären, auf welche kognitiven Verarbeitungsprozesse Reaktionszeitunterschiede unter den jeweiligen experimentellen Bedingungen zurückzuführen sind. Zur Analyse der kognitiven Prozesse wurden in dieser Untersuchung die CNV und P300 herangezogen. Es wurden zwei Altersgruppen (20-30 Jährige und 49-61 Jährige) untersucht. Den Probanden wurden Ziffern präsentiert, die entweder nach dem numerischen Wert oder der Schriftgröße mit dem Hinweisreiz, der Zahl 5, verglichen werden sollten. Die Stimuli wurden nach dem Alternating-Runs-Paradigma dargeboten (Rogers und Monsell, 1995).<br> Erwartungsgemäß gab es Reaktionszeitunterschiede zwischen alt und jung mit längeren Reaktionszeiten für die älteren Probanden. Altersunterschiede in den Fehlerraten ließen sich nicht nachweisen. Möglicherweise erfolgte die Reaktionsauswahl bei den Älteren überlegter aus als bei den Jüngeren. Dies spiegelte sich in längeren aber fehlerfreien Reaktionen wider. Vermutlich bereiteten jedoch alle Probanden in dem Intervall zwischen Cue und Stimulus das jeweilige Aufgabenset komplett vor. Das könnte auch erklären, warum es bei einem Aufgabenwechsel nicht zu einem Anstieg der Reaktionszeit und der Fehlerrate kam. Entgegen der Erwartung zeigten sich keine Wechselkosten. Teilweise wurden inverse Wechselkosten nachgewiesen. In Bezug auf die Wechselkosten konnte das Stufenmodell der exekutiven Kontrolle (Rubinstein et al., 2001) nicht bestätigt werden. Der explizite Hinweisreiz scheint allerdings Einfluss auf die Wechselkosten zu haben. Verschiedene Erklärungsansätze werden diskutiert.<br> Die Contingent Negative Variation ist wie erwartet vor einem Aufgabenwechsel größer als vor einer Aufgabenwiederholung. Durch den Hinweisreiz ist eine erhöhte Kapazität vorhanden. Entsprechend den Ergebnissen der CNV kann davon ausgegangen werden, dass ältere Erwachsene stärker von der Vorinformation zu profitieren scheinen als jüngere Erwachsene. Die älteren Erwachsenen beginnen im Gegensatz zu den jüngeren Erwachsenen offenbar eher mit der Vorbereitung. Zeitdruck und Aufgabenwechsel lösen eine stärkere P300 aus. Demzufolge scheinen Zeitdruck und Aufgabenwechsel einen erhöhten Kapazitätsbedarf zu erfordern. Im Sinne des Stufenmodells der exekutiven Kontrolle von Rubinstein et al. (2001) führt die Zielverschiebung bei einem Aufgabenwechsel zu einer größeren P300. Die Resultate der hier dargestellten Untersuchungen verdeutlichen, dass ältere Erwachsene einen höheren zeitlichen Aufwand in den Stufen der einzelnen exekutiven Prozesse benötigen. Dies spricht für die Hypothese der selektiven Verlangsamung. Ältere kompensieren dies durch einen höheren Aufwand in der Vorbereitung, was auf elektrokortikaler Ebene nachweisbar ist, sind aber nicht in der Lage, dies in den Reaktionszeiten umzusetzen.<br> Die Ergebnisse dieser Untersuchung unterstützen die vereinfachte Annahme von Rubinstein et al. (2001), nach dem die Teilprozesse der Reaktionszeit seriell verarbeitet werden können. Die Resultate lassen allerdings den Schluss zu, dass die Wechselkosten im Hinblick auf die Reaktionszeiten nicht der geeignete Parameter für die Messung der exekutiven Kontrolle sind.<br> Die vorgeschlagene Modifikation des Modells von Rubinstein et al. (2001) in der Vorbereitung auf eine Aufgabe gilt es in weiteren Untersuchungen zu bestätigen und die Möglichkeit der Anwendung auf alle Aspekte der exekutiven Kontrollprozesse zu prüfen. / The aim of this study was it to examine cognitive processes not only on the basis achievement parameters by means of the alternating runs paradigm, but additionally by electricalphysiological parameters. Parameters of event-correlated brain potentials (EKP) were also used to estimate age-related changes in tasks of response time.<br> According to Rubinstein et al. (2001) the response time consists of the duration of serially arranged processing levels. In Rubinstein's et al. (2001) stage model of the executive control processes of implementing control are involved only in switch trials and can run separately from the task processes. The information from response times do not aloud to define what cognitive processing processes are responsible for response time differences in respective to the experimental conditions. In this study the contingent negative variation (CNV) and P300 were used for the analysis of the cognitive processes.<br> Two age groups (20 to 30, and 49 to 61 years old) were included in the study. Numbers were presented, which should be compared to the cue number 5 either to the numeric value or character size. The stimuli were represented after the alternating runs paradigm (Rogers & Monsell, 1995).<br> As expected there were response time differences between old and young subjects with longer response times for the older ones. Age differences in the error rates could not be proven. It is possible that the reaction selection in older ones took place with more consideration than in the younger ones. This is reflected in longer but error free reactions. Probably all subjects prepared in the interval the respective task set between cue and stimulus completely. This could also explain, why with a task switching no rise of the response time and the error rate was noticed. Against expectation no switch costs showed up. Inverse switch costs were partly proven. Regarding the switch costs the stage model of the executive control (Rubinstein et al., 2001) could not be confirmed. The explicit cue however seems to have influence on the switch costs. Different explanations are discussed.<br> The contingent negative variation is higher before a task switching than before a repetition of task. By the cue an increased capacity is presented. According to the results of the CNV it can be assumed that older adults seem to profit more strongly than younger adults from the advance information. Obviously the older adults begin earlier with the preparation than the younger ones. Time pressure and task switching release a stronger P300. Therefore time pressure and task switching seem to require an increased capacity need. According to the stage model of the executive control (Rubinstein et al., (2001) the goal shift with goes along with the task switching leads to a higher P300.<br> The results of the study represented here clarify, that older adults need a more time in the stages of the individual executives of processes. This underlines the hypothesis of the selective slowing down. Older ones compensate this by more effort to preparation, which can be proven on the electrocortical level. The are not able to show this in the the response times, though. The results of this study support the simplified acceptance of Rubinstein et al. (2001), after which the subprocesses of the response time can be processed serially.<br> The results permit the conclusion that the switch costs regarding the response times are not the adaquate parameter for the measurement of the executive control.<br> The suggested modification of the model of Rubinstein et al. (2001) in the preparation for a task it applies to be confirmed in further investigations and the possibility of application to all aspects of the executives has to be tested.

Plasticity is a central concept within the life-span approach of development and is defined as the ability of an individual to change and reorganize in response to environmental challenges (e.g., Baltes & Singer, 20019. Such intraindividual changes can be induced by systematic cognitive training. Recent studies suggest that substantial amounts of plasticity can be induced in executive control functions with a process-based training approach. These newer studies show that repeated practice on executive control tasks not only improved performance on these trained tasks, but also led to improvements in nontrained tasks (i.e., transfer; e.g., Jaeggi, Buschkuehl, Jonides, & Perrig, 2008; Karbach & Kray, 2009). Executive control processes are especially relevant from a developmental perspective because executive control is involved in a wide range of complex cognitive activities (e.g., van der Sluis, de Jong, & van der Leij, 2007) and is one of the most central areas of cognitive development (e.g., Craik & Bialystok, 2006). The current thesis aimed at elucidating several important questions concerning the plasticity of executive control functions induced by systematic cognitive training. Firstly, the amount, range, and stability of plasticity in adolescents and older adults were investigated. Secondly, studies explored if training design, age, and interindividual differences moderate the amount and range of plasticity. Furthermore, the current thesis aimed at exploring how process-based training specifically leads to transfer effects. To explore these questions, all studies employed a pretest-posttest-design comparing a group of participants that was trained with a process-based training approach to a group of control partici-pants that did not receive the training. Pretraining and posttraining sessions incorporated systematic assessment of transfer measures in different cognitive domains. The first study set out to investigate if executive control can be trained in adolescents with a task switching training. Additionally, the study explored what particular domains of executive control may underlie training and transfer effects, and if acute bouts of exercise directly prior to cognitive training enhance training effects. Analyses indicated substantial training effects for both training groups (with or without acute exercise) and near transfer to a similar switching task. Other findings of transfer were limited to a speed task and a tendency for faster reaction times in an updating task. Thus, findings indicate, for the first time, that executive control can be enhanced in adolescents through a short training. Furthermore, analyses suggest that updating may be of particular relevance for the effects of the task switching training. Analyses revealed no additional effects of the exercise intervention. The second study set out to explore, for the first time, the effects of a process-based training ap-proach in old-old age (above 80 years). After ten sessions of practice on working memory tasks, the training group improved in four of the five trained tasks, emphasizing the potential for plasticity even in old-old age. The gains in the training group were largely driven by individuals who started out with a low capacity in the training tasks. Thus, findings suggest that working memory can be improved with a short executive control training even in old-old age, particularly for low-capacity individuals. The absence of transfer effects in this study may point to the limits of plasticity in this age group. The third study aimed at further elucidating the mixed findings regarding the amounts of training and transfer effects induced by executive control training in older adults. For that purpose, a sample of older adults covering a wide range from young-old to old-old age (65 to 95 years) was either trained for nine sessions on a visuospatial and a verbal working memory as well as an executive control task; or served as controls. Analyses revealed significant training effects in all three trained tasks, as well as near transfer to verbal working memory and far transfer to a nonverbal reasoning task. Remarkably, all training effects and the transfer effect to verbal working memory were even stable at a nine-month follow-up. These findings suggest that cognitive plasticity is preserved over a large range of old age and that even a rather short training regimen can lead to (partly specific) training and transfer effects. However, analyses also revealed that there are a range of factors that may moderate the amount of plasticity, e.g., age and baseline performance in the training domain. To summarize, the current thesis explored effects of short executive control trainings on cognitive functions in adolescents and older adults. The findings suggest a high potential for intraindividual variability across the whole life-span. Plasticity was shown on the level of training and transfer tasks, as well as on the level of stability of effects. Furthermore, results support the notion that process-based training improves executive control processes that in turn lead to improvements in tasks that rely on these processes. The current thesis makes important contributions to the conceptual debate about the potentials and limits of training-induced plasticity across the life-span. It benefits the debate in that it specifically delineates factors that moderate the obtained effects.

Using orthogonal subtractions of performance in selected conditions the attentional network test (ANT) measures the efficacy of three isolable components of attention: alerting, orienting, and executive control. This dissertation evaluated: 1) the relationship between these attention networks and absentmindedness measured by the Cognitive Failures Questionnaire (CFQ) and 2) stability, isolability, robustness, and reliability of the two versions of the ANT (Fan et al., 2002 and Callejas et al., 2005) with young adults and older adults and of the child version of the ANT (Rueda et al., 2004) with young children when tested over 10 sessions. A greater degree of absentmindedness as measured with CFQ was associated with a greater alerting network score in RT and with a greater orienting network scores in error rate when the ANT-I was used. However, a greater degree of absentmindedness was associated with a smaller orienting network score in error rate when the ANT was used. These results suggest that the alerting and the orienting networks are related to absentmindedness. However, the orienting networks in the two ANTs were related to absentmindedness differently which supports the proposal (Klein, 2009) that there are fundamental differences between attention when controlled endogenously (ANT) as opposed to exogenously (ANT-I). For young adults and older adults, all network scores in RT remained robust even after nine previous sessions despite some practice effects especially in the executive network both with the ANT and the ANT-I. There was some evidence that the networks do not operate independently in all situations. As expected, reliability increased as more data are added. For young children, only the alerting network scores remained robust over time. Learning effects were observed only with the executive network. The reliability was poor even when more data were added. This made it difficult to assess the isolability of the network scores. The ANT and the ANT-I were associated to the CFQ scores in a limited way. The ANT and the ANT-I can be used for applications requiring repeated testing, but the child ANT may not be suitable for such purpose. / This is a thesis that is manuscript-based.