This study investigates the effects of frequency variance on duration perception, using musically trained subjects. In the experiment three silent duration intervals were examined (4.75, 5.00, and 5.25 seconds); each interval was preceded and followed by tone markers. The onset marker was preceded by seven discrete tones one second apart, on the frequency 174.968 Hertz. This established a pulse or an external standard time measure. The subjects made judgments as to whether the offset marker fell "before," "on," or "after," the pulse. The offset marker had a variable frequency. In the study, the direction of the frequency change, the distance of frequency change, and the mathematical intervallic relationships of the two frequencies show possible influence on duration perception.

A ocorrência repetida de um estímulo sensorial precedendo o estímulo alvo geralmente reduz o tempo de reação (TR). Este efeito tem sido atribuído à atenção temporal mobilizada pelo estímulo precedente que facilitaria a resposta no momento em que o estímulo alvo fosse esperado. Examinamos a atuação da estimulação precedente em tarefas de TR de discriminação sensorial. Em um primeiro experimento testamos noventa e seis adultos jovens de ambos os sexos. Metade dos participantes realizou uma tarefa de TR que exigia a localização (esquerda ou direita) dos estímulos alvos visuais ou auditivos. A outra metade dos participantes realizou uma tarefa de TR que exigia a identificação da forma, no caso de estímulos visuais, e da seqüência de tons, no caso de estímulos auditivos. O estímulo alvo visual podia ser um círculo ou uma elipse. O estímulo alvo auditivo podia ser uma seqüência ascendente constituída por um tom de 1000 Hz seguido por um tom de 3000 Hz ou uma seqüência descendente formada por um tom de 3000 Hz seguido por um tom de 1000 Hz. A resposta consistiu em pressionar uma tecla com a mão esquerda ou a direita dependendo do estímulo alvo o mais rápido possível. O estímulo alvo podia ser precedido pelo piscar de um retângulo com as dimensões da tela do monitor de vídeo ou por um tom de 300 Hz e 57 dB. A assincronia entre o início dos dois estímulos (AIE) podia ser de 50, 100, 200, 400, 800 ou 1600 ms, em blocos de tentativas separados. Nas tarefas de localização, o estímulo precedente visual produziu efeito facilitador na AIE de 400 ms quando o estímulo alvo era visual. O estímulo precedente auditivo produziu efeito facilitador nas AIE de 50, 100, 200, 400, 800 e de 1600 ms quando o estímulo alvo era visual e nas AIE de 400, 800 e 1600 ms quando o estímulo alvo era auditivo. Nas tarefas de identificação, o estímulo precedente auditivo produziu efeito facilitador nas AIE de 200 e 400 ms quando o estímulo alvo era visual e nas AIE de 400, 800 e 1600 ms quando o estímulo alvo era auditivo. Em um segundo experimento, equilibramos o nível de dificuldade das tarefas de discriminação visual com estimulação precedente auditiva. Doze participantes realizaram uma tarefa de TR que exigia a localização do estímulo (acima e abaixo do ponto de fixação, tanto à esquerda como à direita). Outros doze participantes realizaram uma tarefa de TR que exigia a identificação da forma para a escolha da mão de resposta. Na tarefa de localização, o estímulo precedente auditivo produziu um efeito facilitador que não diferiu entre as AIE. Na tarefa de identificação, o estímulo precedente auditivo produziu efeito facilitador na AIE de 400 ms. A mobilização da atenção temporal e sua atuação ao longo do tempo dependem do tipo de tarefa realizada e da natureza do estímulo precedente e do estímulo alvo. Estímulos auditivos mobilizam mais intensamente a atenção temporal do que estímulos visuais / The repeated occurrence of a prime stimulus preceding a target stimulus reduces a reaction time (RT). This effect has been usually attributed to the temporal attention mobilized by the prime stimulus which would facilitate the response at the moment that the target stimulus is expected. We systematically examined the influence of temporal attention on RT in sensory discrimination tasks. In one experiment we tested ninety-six young adults of both sexes. Half of the participants carried out a task which required the identification of the location of appearance of target auditory or visual stimuli (left or right). The other half of the participants carried out a task which required the identification of the shape, in the case of visual stimuli, and tones sequence, in the case of auditory stimuli. The visual target stimulus could be a circle or an ellipse. The auditory target stimulus could be an ascending sequence formed by a 1000 Hz tone followed by a 3000 Hz tone or a descending sequence formed by a 3000 Hz tone followed by a 1000 Hz tone. The response was a key press, which should be performed as fast as possible. The target stimulus could be preceded by the flashing of the border of the screen or by a 57 dB 300 Hz tone. The stimulus onset asynchronies (SOA) could be 50, 100, 200, 400, 800 or 1600 ms, in separated blocks of trials. In the identification tasks location, the visual prime stimulus produced facilitatory effect for SOA of 400 ms when the target stimulus was visual. The auditory prime stimulus produced a facilitatory effect for SOA of 50, 100, 200, 400, 800, and of 1600 ms when the target stimulus was visual and for SOA of 400, 800, and 1600 ms when the target stimulus was auditory. In the tasks of object identification, the auditory prime stimulus produced a facilitatory effect for SOA of 200 and 400 ms when the target stimulus was visual and for SOA of 400, 800 and 1600 ms when the target stimulus was auditory. In another experiment, we balanced the level of difficult of the visual discrimination tasks. We tested only the auditory prime stimulus. Twelve participants carried out a task which required the identification of the location of the target stimulus (upper and lower visual hemifield on left or right of the fixation point). Another twelve participants carried out a task which required the identification of the shape of the target stimulus. In the task of location identification, the auditory prime stimulus produced a facilitatory effect independent of the SOA. In the task of shape identification, the auditory prime stimulus produced a facilitatory effect for SOA of 400 ms. The mobilization of temporal attention and the time course depend on the type of task being performed and the nature of the prime and the target stimulus. Auditory prime stimuli mobilize temporal attention more intensely than visual prime stimulus

Os objetivos deste trabalho são avaliar o papel da atenção na percepção de tempo em jovens, idosos e pacientes com a doença de Alzheimer (DA). Nosso trabalho experimental consiste em 4 experimentos. Os experimentos 1 e 2 avaliaram a percepção de tempo em jovens, empregando tarefas de reprodução e de discriminação de durações temporais, respectivamente. Os resultados mostram um efeito atencional nas durações curtas com menor d. Os experimentos 3 e 4 compararam a percepção de tempo entre jovens, idosos e pacientes com DA, empregando tarefas de reprodução e de discriminação de tempo, respectivamente. Os resultados mostram um pior desempenho de idosos e pacientes com DA em relação aos jovens, que parece corresponder a uma deficiência atencional. Concluímos que a modulação da atenção apresenta papel fundamental e crítico na percepção de tempo e os déficits na percepção de tempo em idosos e em pacientes com DA parecem estar associada a uma menor quantidade de recursos atencionais ou a uma dificuldade de focar a atenção. / Our work focused on the attentional modulation of the perception of time. Additionally, other objective was to study the effect of aging and Alzheimers disease (DA) on temporal perception. We have performed four experiments. The first and the second experiments evaluated time perception in young volunteers, by means of the reproduction and discrimination of time intervals, respectively. The results showed an effect of attention on short durations, confirmed by d. The third and fourth experiments had the objective to compare time perception among young volunteers, elderly and DA patients, utilizing reproduction and discrimination of time intervals, respectively. Our findings showed a worse performance in both elderly volunteers and patients with DA in comparison with the group of young volunteers. Our conclusion is that time perception deficits in elderly and patients with DA are associated either to lesser attentional resources or to an increased difficulty in focusing attention on the target, which is more evident in patients suffering of DA.

La schizophrénie est caractérisée par une importante variabilité symptomatique et fonctionnelle au cours du temps. Néanmoins, peu d’informations sont disponibles concernant la variabilité à court-terme des symptômes et des phénomènes associés (fonctionnement cognitif, expériences émotionnelles, perception du temps), dont la considération est pourtant fondamentale pour une description précise de cette pathologie complexe. Les approches d’évaluation traditionnelles conduites en laboratoire sont confrontées à un certain nombre de limites méthodologiques ne permettant pas d’apprécier cette variabilité. La problématique de cette thèse est d’apporter des informations manquantes concernant les liens à court terme entre cognition, expériences émotionnelles, perception du temps et symptômes de la schizophrénie, tels qu’ils se manifestent en vie quotidienne, et leurs corrélats cérébraux. Pour répondre à cette problématique, une approche novatrice combinant des méthodes d’évaluation écologique momentanée (EMA) via technologies mobiles et d’Imagerie par Résonance Magnétique (IRM) a été appliquée. La méthodologie EMA employée a permis de mettre en évidence l’implication des performances cognitives, des expériences émotionnelles et de la perception du temps dans l’expression des symptômes de la schizophrénie sur des périodes de temps brèves dans la vie quotidienne des patients. L’IRM a permis de révéler certains corrélats anatomiques et fonctionnels de ces relations, confirmant notamment le rôle central des régions fronto-temporo-cérébelleuses dans ce trouble. / Schizophrenia is characterized by significant variability over time in symptoms and functioning. However, little information is available concerning the short-term variability of symptoms and their associated phenomena (cognitive functioning, emotional experiences, perception of time), and despite their importance for providing precise descriptions of this complex mental disorder. Traditional laboratory-based assessments are confronted with a number of methodological limitations that make it impossible to assess such variability. This doctoral thesis therefore aims at providing missing information concerning the short-term temporal links between cognitive functioning, emotional experience, and time perception relative to the manifestation of symptoms of schizophrenia and examines the cerebral correlates of these associations. To address this issue, an innovative approach was applied that combined Ecological Momentary Assessment (EMA) using mobile technologies with Magnetic Resonance Imaging (MRI) of the brain. The EMA methodology identified the roles of cognitive performance, emotional experience and time perception in the expression of symptoms of schizophrenia over short time intervals in the patient’s daily life. MRI revealed the anatomical and functional correlates of these relationships, confirming in particular the central role of fronto-temporo-cerebellar regions in this disorder. Taken together, this dual approach provides novel insights into the underlying mechanisms of symptom expression in individuals with schizophrenia.

<p>Interval timing, defined as timing and time perception in the seconds-to-minutes range, is a higher-order cognitive function that has been shown to be critically dependent upon cortico-striatal circuits in the brain. However, our understanding of how different neuronal subtypes within these circuits cooperate to subserve interval timing remains elusive. The present study was designed to investigate this issue by focusing on the spike waveforms of neurons and their synchronous firing patterns with local field potentials (LFPs) recorded from cortico-striatal circuits while rats were performing two standard interval-timing tasks. Experiment 1 demonstrated that neurons in cortico-striatal circuits can be classified into 4 different clusters based on their distinct spike waveforms and behavioral correlates. These distinct neuronal populations were shown to be differentially involved in timing and reward processing. More importantly, the LFP-spike synchrony data suggested that neurons in 1 particular cluster were putative fast-spiking interneurons (FSIs) in the striatum and these neurons responded to both timing and reward processing. Experiment 2 reported electrophysiological data that were similar with previous findings, but identified a different cluster of striatal neurons - putative tonically-active neurons (TANs), revealed by their distinct spike waveforms and special firing patterns during the acquisition of the task. These firing patterns of FSIs and TANs were in contrast with potential striatal medium-spiny neurons (MSNs) that preferentially responded to temporal processing in the current study. Experiment 3 further investigated the proposal that interval timing is subserved by cortico-striatal circuits by using microstimulation. The findings revealed a stimulation frequency-dependent "stop" or "reset" response pattern in rats receiving microstimulation in either the cortex or the striatum during the performance of the timing task. Taken together, the current findings further support that interval timing is represented in cortico-striatal networks that involve multiple types of interneurons (e.g., FSIs and TANs) functionally connected with the principal projection neurons (i.e., MSNs) in the dorsal striatum. When specific components of these complex networks are electrically stimulated, the ongoing timing processes are temporarily "stopped" or "reset" depending on the properties of the stimulation.</p> / Dissertation

[Truncated abstract] This thesis presents three different methods to investigate flexural wave propagation and scattering, power flow and transmission efficiencies, and dynamic stress concentration and fatigue failures in structural dynamics. The first method is based on the acoustical wave propagator (AWP) technique, which is the main part described in this thesis. Through the numerical implementation of the AWP, the complete information of the vibrating structure can be obtained including displacement, velocity, acceleration, bending moments, strain and stresses. The AWP technique has been applied to systems consisting of a one-dimensional stepped beam, a two-dimensional thin plate, a thin plate with a sharp change of section, a heterogeneous plate with multiple cylindrical patches, and a Mindlin?s plate with a reinforced rib. For this Mindlin?s plate structure, through the comparison of the results obtained by Mindlin?s thick plate theory and Kirchhoff?s classical thin plate theory, the difference of theoretical predicted results is investigated. As part of these investigations, reflection and transmission coefficients, power flow and transmission efficiencies in a onedimensional stepped beam, and power flow in a two-dimensional circular plate structure, are studied. In particular, this technique has been successfully extended to investigate wave propagation and scattering, and dynamic stress concentration at discontinuities. Potential applications are fatigue failure prediction and damage detection in complex structures. The second method is based on experimental techniques to investigate the structural response under impact loads, which consist of the waveform measuring technique in the time domain by using the WAVEVIEW software, and steady-state measurements by using the Polytec Laser Scanning Vibrometer (PLSV) in the frequency domain. The waveform measuring technique is introduced to obtain the waveform at different locations in the time domain. These experimental results can be used to verify the validity of predicted results obtained by the AWP technique. Furthermore, distributions of dynamic strain and stress in both near-field (close to discontinuities) and far-field regions are investigated for the study of the effects of the discontinuities on reflection and transmission coefficients in a one-dimensional stepped beam structure. Experimental results in the time domain can be easily transferred into those in the frequency domain by the fast Fourier transformation, and compared with those obtained by other researchers. This PLSV technique provides an accurate and efficient tool to investigate mode shape and power flow in some coupled structures, such as a ribbed plate. Through the finite differencing technique, autospectral and spatial of dynamic strain can be obtained. The third method considered uses the travelling wave solution method to solve reflection and transmission coefficients in a one-dimensional stepped beam structure in the time domain. In particular, analytical exact solutions of reflection and transmission coefficients under the given initial-value problem are derived. These analytical solutions together with experimental results can be used to compare with those obtained by the AWP technique.

Silence is a negative term denoting absence of sounds. However, our ordinary way of speaking about silence suggests that the latter is some perceptible reality, 'some- thing' perceived. But is it legitimate to say that we hear silence - absence of sound? What implications about perception does such a way of speaking have? The aim of the present thesis is to analyse these questions. The analysis unfolds along three axes. The first part of the thesis reconstructs the problem of perception of silence in John Cage's 'silent piece' 4'33" in context of its conceptual origin, Cage's aesthetics, and reflection of his work in his written texts. Hence the introduction of the problem of perceptible silence in recent thought. It discusses the thesis that we cannot hear absolute silence, not even in the soundproof chamber, and considers the question whether it is adequate to say that we can hear silence if we expect to hear music, but the music does not sound - a question that was raised by the premiere of 4'33". The second part of the thesis scrutinizes the position according to which we can directly hear/listen to silence which is the absence of sounds, namely the arguments of Roy Sorensen and Ian Phillips. Emphasis is put on Sorensen's theory since it is in direct contrast to Cage's position (though Sorensen...

Os objetivos deste trabalho são avaliar o papel da atenção na percepção de tempo em jovens, idosos e pacientes com a doença de Alzheimer (DA). Nosso trabalho experimental consiste em 4 experimentos. Os experimentos 1 e 2 avaliaram a percepção de tempo em jovens, empregando tarefas de reprodução e de discriminação de durações temporais, respectivamente. Os resultados mostram um efeito atencional nas durações curtas com menor d. Os experimentos 3 e 4 compararam a percepção de tempo entre jovens, idosos e pacientes com DA, empregando tarefas de reprodução e de discriminação de tempo, respectivamente. Os resultados mostram um pior desempenho de idosos e pacientes com DA em relação aos jovens, que parece corresponder a uma deficiência atencional. Concluímos que a modulação da atenção apresenta papel fundamental e crítico na percepção de tempo e os déficits na percepção de tempo em idosos e em pacientes com DA parecem estar associada a uma menor quantidade de recursos atencionais ou a uma dificuldade de focar a atenção. / Our work focused on the attentional modulation of the perception of time. Additionally, other objective was to study the effect of aging and Alzheimers disease (DA) on temporal perception. We have performed four experiments. The first and the second experiments evaluated time perception in young volunteers, by means of the reproduction and discrimination of time intervals, respectively. The results showed an effect of attention on short durations, confirmed by d. The third and fourth experiments had the objective to compare time perception among young volunteers, elderly and DA patients, utilizing reproduction and discrimination of time intervals, respectively. Our findings showed a worse performance in both elderly volunteers and patients with DA in comparison with the group of young volunteers. Our conclusion is that time perception deficits in elderly and patients with DA are associated either to lesser attentional resources or to an increased difficulty in focusing attention on the target, which is more evident in patients suffering of DA.

A ocorrência repetida de um estímulo sensorial precedendo o estímulo alvo geralmente reduz o tempo de reação (TR). Este efeito tem sido atribuído à atenção temporal mobilizada pelo estímulo precedente que facilitaria a resposta no momento em que o estímulo alvo fosse esperado. Examinamos a atuação da estimulação precedente em tarefas de TR de discriminação sensorial. Em um primeiro experimento testamos noventa e seis adultos jovens de ambos os sexos. Metade dos participantes realizou uma tarefa de TR que exigia a localização (esquerda ou direita) dos estímulos alvos visuais ou auditivos. A outra metade dos participantes realizou uma tarefa de TR que exigia a identificação da forma, no caso de estímulos visuais, e da seqüência de tons, no caso de estímulos auditivos. O estímulo alvo visual podia ser um círculo ou uma elipse. O estímulo alvo auditivo podia ser uma seqüência ascendente constituída por um tom de 1000 Hz seguido por um tom de 3000 Hz ou uma seqüência descendente formada por um tom de 3000 Hz seguido por um tom de 1000 Hz. A resposta consistiu em pressionar uma tecla com a mão esquerda ou a direita dependendo do estímulo alvo o mais rápido possível. O estímulo alvo podia ser precedido pelo piscar de um retângulo com as dimensões da tela do monitor de vídeo ou por um tom de 300 Hz e 57 dB. A assincronia entre o início dos dois estímulos (AIE) podia ser de 50, 100, 200, 400, 800 ou 1600 ms, em blocos de tentativas separados. Nas tarefas de localização, o estímulo precedente visual produziu efeito facilitador na AIE de 400 ms quando o estímulo alvo era visual. O estímulo precedente auditivo produziu efeito facilitador nas AIE de 50, 100, 200, 400, 800 e de 1600 ms quando o estímulo alvo era visual e nas AIE de 400, 800 e 1600 ms quando o estímulo alvo era auditivo. Nas tarefas de identificação, o estímulo precedente auditivo produziu efeito facilitador nas AIE de 200 e 400 ms quando o estímulo alvo era visual e nas AIE de 400, 800 e 1600 ms quando o estímulo alvo era auditivo. Em um segundo experimento, equilibramos o nível de dificuldade das tarefas de discriminação visual com estimulação precedente auditiva. Doze participantes realizaram uma tarefa de TR que exigia a localização do estímulo (acima e abaixo do ponto de fixação, tanto à esquerda como à direita). Outros doze participantes realizaram uma tarefa de TR que exigia a identificação da forma para a escolha da mão de resposta. Na tarefa de localização, o estímulo precedente auditivo produziu um efeito facilitador que não diferiu entre as AIE. Na tarefa de identificação, o estímulo precedente auditivo produziu efeito facilitador na AIE de 400 ms. A mobilização da atenção temporal e sua atuação ao longo do tempo dependem do tipo de tarefa realizada e da natureza do estímulo precedente e do estímulo alvo. Estímulos auditivos mobilizam mais intensamente a atenção temporal do que estímulos visuais / The repeated occurrence of a prime stimulus preceding a target stimulus reduces a reaction time (RT). This effect has been usually attributed to the temporal attention mobilized by the prime stimulus which would facilitate the response at the moment that the target stimulus is expected. We systematically examined the influence of temporal attention on RT in sensory discrimination tasks. In one experiment we tested ninety-six young adults of both sexes. Half of the participants carried out a task which required the identification of the location of appearance of target auditory or visual stimuli (left or right). The other half of the participants carried out a task which required the identification of the shape, in the case of visual stimuli, and tones sequence, in the case of auditory stimuli. The visual target stimulus could be a circle or an ellipse. The auditory target stimulus could be an ascending sequence formed by a 1000 Hz tone followed by a 3000 Hz tone or a descending sequence formed by a 3000 Hz tone followed by a 1000 Hz tone. The response was a key press, which should be performed as fast as possible. The target stimulus could be preceded by the flashing of the border of the screen or by a 57 dB 300 Hz tone. The stimulus onset asynchronies (SOA) could be 50, 100, 200, 400, 800 or 1600 ms, in separated blocks of trials. In the identification tasks location, the visual prime stimulus produced facilitatory effect for SOA of 400 ms when the target stimulus was visual. The auditory prime stimulus produced a facilitatory effect for SOA of 50, 100, 200, 400, 800, and of 1600 ms when the target stimulus was visual and for SOA of 400, 800, and 1600 ms when the target stimulus was auditory. In the tasks of object identification, the auditory prime stimulus produced a facilitatory effect for SOA of 200 and 400 ms when the target stimulus was visual and for SOA of 400, 800 and 1600 ms when the target stimulus was auditory. In another experiment, we balanced the level of difficult of the visual discrimination tasks. We tested only the auditory prime stimulus. Twelve participants carried out a task which required the identification of the location of the target stimulus (upper and lower visual hemifield on left or right of the fixation point). Another twelve participants carried out a task which required the identification of the shape of the target stimulus. In the task of location identification, the auditory prime stimulus produced a facilitatory effect independent of the SOA. In the task of shape identification, the auditory prime stimulus produced a facilitatory effect for SOA of 400 ms. The mobilization of temporal attention and the time course depend on the type of task being performed and the nature of the prime and the target stimulus. Auditory prime stimuli mobilize temporal attention more intensely than visual prime stimulus

La métacognition concerne à la fois les connaissances des individus sur leur fonctionnement cognitif et les processus qui permettent de les réguler (Koriat, 2007). Or, l’étude de la perception du temps a mis en évidence que de nombreux éléments peuvent provoquer des distorsions temporelles, notamment, par exemple, l’attention ou les feedbacks. L’objectif de ce travail est donc de proposer un modèle intégratif de la métacognition de la perception du temps ; autrement dit d’intégrer les données issues des recherches classiques sur la perception du temps au sein d’un modèle métacognitif (Nelson et Narens, 1990).Notre première question était de vérifier l’existence de connaissances sur la perception du temps, et en particulier sur les facteurs à l’origine de distorsions temporelles. Les 3 expériences de notre première étude nous ont conduit à créer et valider le Questionnaire Métacognitif sur le Temps (MQT). Ce dernier, constitué de 24 items, met en évidence l’existence de connaissances plus fiables pour soi (sous-échelle Soi, 12 items) que pour autrui (sous-échelle Autrui, 12 items), sur deux facteurs connus pour affecter la perception du temps : le facteur Emotion (4 items) et le facteur Attention (8 items).Dans un deuxième temps, nous avons étudié l’influence des processus métacognitifs sur les jugements temporels. Ainsi, nous nous sommes intéressées à l’influence du processus de Contrôle métacognitif sur la performance à deux tâches temporelles. Notre hypothèse était que les connaissances sur le temps permettaient de réguler les jugements temporels. Les résultats de nos deux études (Etude 2 et 3, respectivement composées de une et deux expériences) ont confirmé l’importance du processus de Contrôle dans le jugement temporel. Ainsi, la simple conscience du rôle de l’attention sur la perception du temps provoque une réduction de l’effet attentionnel généralement observé (Etude 2). De plus, les connaissances explicites, erronées, données aux individus, provoquent une réduction voire une disparition de l’effet émotionnel automatique de la colère sur les jugements temporels (Etude 3). Enfin, nous avons exploré le lien entre processus de Monitoring et jugements temporels. Notre quatrième étude a mis en évidence la capacité des individus à estimer précisément la justesse de leurs jugements temporels sous certaines conditions. En effet, il apparaît que les individus sont sensibles à la difficulté de la tâche et à la gamme de durée. Ces deux dimensions affectent à la fois les jugements temporels et les jugements de certitude.Dans l’ensemble, les résultats de ce travail soulignent l’importance qu’il y a à tenir compte des processus métacognitifs dans l’étude de la perception du temps. / Metacognition concerns both individuals' knowledge about their cognitive functioning and the processes that regulate them (Koriat, 2007). The study of the perception of time showed that many factors cause temporal distortions, including, for example, attention or feedback. The purpose of this work is thus to propose an integrative model of metacognition of time perception; i.e. to integrate data based on conventional research on the perception of time in a metacognitive model (Nelson and Narens 1990).Our first question was to verify the existence of knowledge about the perception of time, especially on the factors responsible for temporal distortions. The three experiments of our first study led us to create and validate the Metacognitive Questionnaire on Time (MQT). The latter consists of 24 items that highlights the existence of knowledge, more reliable for oneself (subscale Self, 12 items) than for others (subscale Others, 12 items), on two factors known to affect time perception: an Emotion Factor (4 items) and an Attention factor (8 items).Secondly, we studied the influence of metacognitive processes on temporal judgments. Thus, we are interested in the influence of metacognitive Control process on performances in two temporal tasks. Our hypothesis was that knowledge about time allowed regulating the temporal judgments. The results of our studies (Study 2 and 3, respectively composed of one and two experiments) confirmed the importance of the Control process on temporal judgments. Thus, mere awareness of the role of attention on perception of time causes a reduction of the attentional effect generally observed (Study 2). Moreover, explicit erroneous knowledge given to participants causes a reduction or even disappearance of automatic emotional effect of anger on the temporal judgments (Study 3). Finally, we have explored the link between Monitoring process and temporal judgments. Our fourth study demonstrated the ability of individuals to accurately estimate the accuracy of their temporal judgments under certain conditions. Indeed, it appears that individuals are sensitive to task difficulty and duration range. These two dimensions affect both temporal judgments and confidence level estimates.Overall, the results of this study emphasize the importance to take account of metacognitive processes in the study of the perception of time.