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Concept

Invisibilité

Résumé

L'invisibilité est l'état d'un objet ou d'un organisme vivant qui ne peut être vu, on dit alors qu'il est invisible. Le terme est utilisé dans de nombreux films et romans de fantasy ou de science-fiction, où les objets sont rendus invisibles par les pouvoirs de la magie ou de la technologie. Cependant, on peut aussi voir ses effets dans le monde réel, dans certains domaines de la physique. Métamatériaux Métamatériaux Dans l'édition du de la revue Science, des chercheurs britanniques et américains ont déclaré que théoriquement l'emploi de métamatériaux pouvait permettre de dévier les rayonnements électromagnétiques (dont la lumière fait partie) et leur faire reprendre une trajectoire « normale » après avoir passé ce dernier. Avec les travaux de l'équipe de David Smith de l'université Duke en Caroline du Nord aux États-Unis d'Amérique, les métamatériaux se limitent à des longueurs d'onde de l'ordre du millimètre qui sont du domaine des micro-ondes. Mais quelques mois plu

Source officielle

https://fr.wikipedia.org/wiki/Invisibilit%C3%A9

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En physique, en électromagnétisme, le terme métamatériau désigne un matériau composite artificiel qui présente des propriétés électromagnétiques qu'on ne retrouve pas dans un matériau naturel. Il s

thumb|Amazing Stories, premier magazine de science-fiction américain. La science-fiction est un genre narratif, principalement littéraire (littérature et bande dessinée), cinématographique et vidéo-l

Metamaterial cloaking is the usage of metamaterials in an invisibility cloak. This is accomplished by manipulating the paths traversed by light through a novel optical material. Metamaterials direct a

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The course teaches the basics of autonomous mobile robots. Both hardware (energy, locomotion, sensors) and software (signal processing, control, localization, trajectory planning, high-level control) will be tackled. The students will apply the knowledge to program and control a real mobile robot.

This course covers the fundamental concepts behind the design, function and application of state-of-the-art biomaterials, that is, materials that are designed based on a molecular understanding of their interactions with biological systems.

This course introduces the fundamentals of stem cell biology, with a particular focus on the role of stem cells during development, tissue homeostasis/regeneration and disease, and the generation of organoids from stem cells

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Publications associées (17)

Temporal structure coding with and without awareness

Nathan Quentin Faivre

In order to interpret a constantly changing environment, visual events far apart in space and time must be integrated into a unified percept. While spatial properties of invisible signals are known to be encoded without awareness, the fate of temporal properties remains largely unknown. Here, we probed temporal integration for two distinct motion stimuli that were either visible or rendered invisible using continuous flash suppression. We found that when invisible, both the direction of apparent motion and the gender of point-light walkers were processed only when defined across short time periods (i.e., respectively 100 ms and 1000 ms). This limitation was not observed under full visibility. These similar findings at two different hierarchical levels of processing suggest that temporal integration windows shrink in the absence of perceptual awareness. We discuss this phenomenon as a key prediction of the global neuronal workspace and the information integration theories of consciousness.

Elsevier2014

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Low-level awareness accompanies “unconscious” high-level processing during continuous flash suppression

Nathan Quentin Faivre

The scope and limits of unconscious processing are a matter of ongoing debate. Lately, continuous flash suppression (CFS), a technique for suppressing visual stimuli, has been widely used to demonstrate surprisingly high-level processing of invisible stimuli. Yet, recent studies showed that CFS might actually allow low-level features of the stimulus to escape suppression and be consciously perceived. The influence of such low-level awareness on high-level processing might easily go unnoticed, as studies usually only probe the visibility of the feature of interest, and not that of lower-level features. For instance, face identity is held to be processed unconsciously since subjects who fail to judge the identity of suppressed faces still show identity priming effects. Here we challenge these results, showing that such high-level priming effects are indeed induced by faces whose identity is invisible, but critically, only when a lower-level feature, such as color or location, is visible. No evidence for identity processing was found when subjects had no conscious access to any feature of the suppressed face. These results suggest that high-level processing of an image might be enabled by-or co-occur with-conscious access to some of its low-level features, even when these features are not relevant to the processed dimension. Accordingly, they call for further investigation of lower-level awareness during CFS, and reevaluation of other unconscious high-level processing findings.

Association for Research in Vision and Ophthalmology2016

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Different combinations of forward and backward masking as well as interocular suppression have been used extensively to render stimuli invisible and to study those aspects of visual stimuli that are processed in the absence of conscious experience. Although the two techniques-masking vs. interocular suppression-obviously differ both in their applications and mechanisms, only little effort has been made to compare them systematically. Yet, such a comparison is crucial: existing discrepancies in the extent of unconscious processing inferred from these two techniques must be reconciled, as our understanding of unconscious vision should be independent of the technique used to prevent visibility. Here, we studied similarities and differences between faces rendered invisible by masking vs. interocular suppression using a priming paradigm. By carefully equating stimulus strength across the two techniques, we analyzed the effects of face primes with the same viewpoint (repetition priming, Experiment 1) and of face primes with a different viewpoint (identity priming, Experiment 2) on the reaction times for a fame categorization task. Overall, we found that the magnitude of both repetition and identity priming largely depended on stimulus visibility. Moreover, when the primes were subjectively invisible, both repetition and identity priming were found to be qualitatively stronger under masking than under interocular suppression. Taken together, these results help refine our understanding of which level of visual processing each technique disrupts, and illustrate the importance of systematic methodological comparisons in the field of unconscious vision.

Frontiers Research Foundation2014

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