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Pietro Roccasecca, en poste à Rome mais en détachement à Tours cette année, lance un appel à communication pour un colloque qu'il organise au Centre d'Etudes Supérieures de la Renaissance les 14 et 15 septembre 2013.Il s'agit de conduire une réflexion commune sur les modalités de la vision (notamment à travers la perspective), en s'inspirant des travaux récents des sciences cognitives. Est joint à cet appel un texte de présentation qui atteste toute la nouveauté de cette approche. Vous pouvez contacter directement l'organisateur (Pietro[point]Roccasecca[at]univ-tours[point]fr).Vision and image-making : constructing the visible and seeing as understanding.Recently, neuroscientists have confirmed that vision is a cognitive process that involves more than one area of the brain. Vision can no longer be understood as a largely passive process in which vision and comprehension correspond to two different brain functions. The neurobiologist Semir Zeki writes: “It is only with the more recent discoveries about the visual brain that our concept of vision as a process has changed. We now view it as an active process in which the brain, in its quest for knowledge about the visual world, discards, selects and, by comparing the selected information to its stored records, generates visual images in the brain, a process remarkably similar to what an artist does” (S. Zeki, Inner Vision: an exploration of art and the brain, Oxford University Press, 1999, p. 21). Zeki takes the example of Picasso, who inherited and the crucial issues and recent findings of these ongoing debates while also reinterpreting and anticipating “with prophetic intuition the current fashion of research on the elaboration of images by the brain” (ibid.), by affirming that it would be interesting to conserve traces of the metamorphosis that a painting in the making encounters by means of photography and that the itinerary chosen by the brain could be discovered by materializing a dream.Zeki´s affirmation that the brain “ generates visual images” following  “a process remarkably similar to what an artist does” is a provocation; Of course it is not the visual cortex that behaves like an artist but the opposite. The artist knows, to whatever extent, the workings  of the cognitive visual process and, foreseeing the cognitive processes that the artwork's future observer will activate during its perception, reproduces it or deceives it, according to the ambitions of his artistic expression.If vision, generally speaking, is a cognitive act, the construction of a pictorial image can be understood as a cognitive process in which the artist involves more than one area of the brain, and the visual perception of this painting can be seen as a cognitive process that involves the same areas of the observer´s brain. From this arises the question: How have artists become aware of the cognitive process of vision? There are two hypotheses, the first being that the artist is a particularly talented individual, gifted with manual abilities that others do not possess, and intuitively able to understand what others can see or understand only if indicated or explained. A second hypothesis holds that the artist's procedures and methods are directly or indirectly influenced by the evolving theories of vision that have modified visual awareness of patrons and artists. One assumption does not exclude the other, but while the theory of the artist as genius has been cultivated from the beginnings of art history well into the 20th century, the theory of the diffusion of the knowledge of the cognitive theory of vision has still to be fully written.The idea of the artwork as the creation of a genius focuses on the moment of the invention: what Vasari called “the first idea”. However, according to the Renaissance theorist, it was indispensable to follow an operative protocol between the first idea and the completed artwork, in order to guarantee its quality. In the Romantic and idealistic conception, the artwork is the material incarnation of the first idea and the operations that transform the invention into the artwork are manual and material activities, unfortunately inevitable, that are ennobled by the hand of the great artist that bestows unity and artistic quality to what would otherwise be a mere work of craftsmanship.The techniques of diagnostic investigation applied to artworks before initiating restoration have produced a vast repertoire of images from which information on the process of the construction of the pictorial image can be drawn. Up until the 1930s, when non-invasive techniques of investigation (X-rays) began to be applied to pre-restoration studies, the only documents available on the process of the construction of the image were functional drawings made, kept and transmitted by the artist. Applying non-destructive investigation technologies enables the  information-gathering on the process of the construction of the pictorial image for those artworks bereft of preparatory drawings. Non-destructive investigation techniques, such as infrared reflectography, allow studying the painting as a palimpsest of different superimposed layers of colour. The study of the functional drawings underlying the pictorial layers and the traces of elaboration of the pictorial layers that are being conducted today with the scope of restoration and conservation, give us the possibility to study essential parts of the process of the construction of the artwork through different pictorial layers. Examples include: the preliminary engravings of perspective constructions, architectonical profiles and figures; the configuration of different planes of depth; the study of the figure (anatomy, attitude and proportion); the configuration of light and shadow in spatial composition; techniques of applying colour.The theory of vision elaborated by the Arabic philosopher Ibn al-Haytham, known in the Latin world as Alhacen, at the beginning of the 11th century, was disseminated in Italy as from the 13th century by  the De aspectibus, the Latin translation of his voluminous treatise in Arab language. Alhacen’s theory of vision, that remained largely valid until the 17th century, contains a theory of the visual characteristics, i.e., the visible qualities recognized by the intellect, that tackles the question of light and colour not only from the point of view of physics, but also according to an approach that in contemporary terms could be defined cognitive-psychological.The Second Book of Alhacen’s De aspectibus enumerates the intentiones, that is, the visual characteristics or visual properties that can be perceived by sight and shows how some and any of them are being perceived. According to Alhacen, each body has visual properties, characteristics that can be known and recognized by the intellect. The first two qualities, light and colour, would be understood by the intellect through the “bare sense“. The other twenty visual experiences, in order to be understood, need the intervention of the virtus distinctiva, that is, the power of discrimination, and therefore are the result of a cognitive activity that acts by comparison and is based on the individual’s previous knowledge.If an artist reproduces the visual characteristics perceived by the intellect in visible objects (for instance light, colour, distance, place, corporeity, figure, number, motion, stillness and shadow) in a drawing or painting, the observer of the drawing or painting will understand them as such. In this sense, Alhacen’s twenty-two intentiones can be understood as a theoretical source of “naturalism” in visual representation.Alhacen’s approach establishes a definite number of visual characteristics. While his hypotheses may retrospectively seem schematic, his hypothesis is nonetheless indirectly buttressed by recent research on the visual brain as pursued by Semir Zeki: in Inner vision Zeki explains that vision happens when and because it involves about thirty areas of the brain. Akin to Alhacen’s “power of discrimination”, the first area that is activated distinguishes information contained in the flow of stimuli that enters the brain and then sends it to others areas of the brain where these are processed. The first thing that this “distinctive” area of the brain recognizes is colour, then, shape. At first it would seem that Alhacen’s cognitive theory and neuroscience describe and treat the visual process in the same way, even if they belong to very different conceptual, methodological and ideological frameworks. The areas of the brain cortex identified by Zeki assume the same functions of recognizing visual characteristics (light, colour, form, figure and motion) as do Alhacen’s intentiones. The possibility of an effective correspondence between the two theories of vision merits fuller examination within the history of science.The working assumption of this conference, then, is that the construction of a painting is a process of formulating and verifying hypotheses, as is any other intellectual process of choice and verification of hypothesis by comparison. Implicit in any literary, musical, architectonical, sculptural or pictorial composition and, last but not least, this process is implicit in any form of scientific or artistic research.The process of transforming and materializing the “first idea” into a completed artwork is most probably the moment in which the artist puts into action the variegated strategies of selection, comparison and choice that Zeki has located as taking place in the visual cortex of the brain and which Picasso would have liked to document beyond his artistic production.The theory of vision of Alhacen, diffused for the first time in the 1270ies at papal court in Viterbo, possibly influenced the making of the frescoes painted in Franciscan Basilica of Assisi.The cognitive part of Alhacen’s theory of vision entered the store of knowledge of 15th- century artists and that was re-elaborated during through to the 16th centuries; it was subsequently transmitted to future generations by the Accademie del Disegno (The Academies of the art of drawing) founded in Florence and Rome towards the end of the 16th century. These academies elaborated a standardized pedagogical model for drawing that was adopted by the European academies who transmitted it almost unaltered until the 20th century.In order to assess this thesis it is necessary to launch a dialog between the history of science and the history of art on several topics, some of which are enlisted as follows and which might be further broadened and defined. Participants are invited to propose a paper on the following topics:- Scientific theories of vision, medieval, early modern and contemporary- Transmission of knowledge between artistic and scientific environments- The pictorial image in the late middle ages- Effects of the “real” in Renaissance painting- Visual representation of direct, reflected and refracted light-Visual documentation of the processes of image construction: functional drawings and visual   documentation produced by investigation preceding restoration- The process of image construction in art treatises and in art theory- Theory of drawing in art treatises- Theory and practice of drawing in the Academies and in artists’ studios