Session 6

There are images neither in the mind nor in the world, only pictures

Riccardo Manzotti
There are no images to be seen, since there are images neither in the mind nor in the world. There are only pictures. The notion of image, historically originated in the philosophy of mind of XVII centuries and in renaissance art development is at the origin of several confusion and vagueness. Contrary the common belief that there are there are images stored in computer memory as well as in other electronic devices and that visual perception deals by means of images projected from the outside world inside our retinas, I will try to show that such claims are only metaphorical. As a result, the neuroscientific and psychological literature referring to retinal images, cortical images, visual mental images, natural images, topographic images, retinotopic images, sensory images, after images are based on wrong premises (Shepard 1978; Zimler and Keenan 1983; Kosslyn, Thompson et al. 1995; Beaulieu 2002; Gregory 2005; Manzotti 2006; Kay, Naselaris et al. 2008; Manzotti 2010). Taking advantage of a few selected cases like mirrors, kaleidoscopes, visual perception, mental images to show that the notion of image is void.

Sensitivity to the Fine Scale of Artistic Style

Holly Gerhard and Matthias Bethge
Human observers are remarkably sensitive to statistical regularities of images occurring at the very fine spatial scale (Gerhard et al., 2011, 40 ECVP Abstract Supplement, 18). Here we show that this exquisite sensitivity can also be used to study artistic style. We present a new paradigm for studying the style of an artist's hand, how he makes his brush or pen strokes. Our paradigm avoids potential interference from cognitive expectations evoked by viewing meaningful elements or an entire work of art. Instead, our stimuli are made of small image patches sampled from images of the original art work and tiled together into textures. The task is forced choice. We applied the paradigm to the question of authenticity: what discriminates works done by a master from those of his imitators? We used eight high quality scans of drawings by Pieter Bruegel the Elder and five of drawings previously considered authentic as stimuli for the texture discrimination task. To identify cues used to discriminate Bruegel from his imitators, we filtered the stimuli for the particular statistical regularities they conveyed. We also compared performance in all conditions with a state-of-the-art statistical discriminator. While the model failed with degraded stimuli, human observers always correctly classified the drawings.

Motion in Art - Art in Motion

Johannes M Zanker
Operating in a three-dimensional world the human visual system is exposed to light changes in three spatial and one temporal dimensions. How would a painter face the challenge to capture such a rich environment on a flat, static canvas? Whereas the rules of occlusion and perspective provide artists with comparatively simple guidance to represent space, a range of rather varied approaches can be found for the representation of motion. Moving on from a symbolic or impressionistic pictorial language for motion, there were several attempt, most notably from the Op Art movement, to recreate an compelling experience of an actual motion percept in arts - such motion illusions have attracted the curiosity of visual scientist to use arts as a tool to understand the mechanisms underlying human perception. In the last decade, the relationship between eye movements and periodic high-contrast patterns that are static but elicit strong motion sensations - such as Riley's 'Fall' - is now well investigated. Whilst this work offers a clear rational to explain the basic mechanisms underlying many of such illusions in their most fundamental configurations, the debate is open whether they can account for other motion illusions experienced in more intricate patterns, such as Leviant's 'Enigma' or Kitaoka's 'Rotating Snake'.

Depiction of material properties in paintings

Bilge Sayim and Patrick Cavanagh
Artists are able to depict various material properties in paintings, such as transparency, gloss, and roughness, by manipulating pigments of different color and lightness. Often observers perceive these properties in paintings, even when the artist did not attempt to create a photorealistic picture but instead depicted simplified, distorted, or caricatured objects and scenes. For example, artists have successfully depicted transparency in simple line drawings, strongly violating physical constraints of transparency. Such pictures show us that stimuli that deviate from or misrepresent object properties may still trigger the perception of various material qualities. Here, we investigate the techniques artists used to depict material properties in paintings, discussing which principles they followed and which they ignored. We show how such paintings may help us to understand the processes underlying visual inferences in the brain.

Eastern and Western Perspectives in Traditional Visual Arts

Yan Bao
Representation is essential to both visual perception and visual art. By comparing the representation styles of traditional paintings from a psychological point of view, different perspectives in eastern and western paintings are put forward. While western artists typically use a geometric perspective to give a distance cue in representing the 3D world, eastern artists tend to adopt a negative perspective or vertical representation of distance. While western artists favor object-centered scenes, eastern artists prefer more context-oriented scenes. Western artists frequently show a direct facing view in their paintings, eastern artists typically demonstrate an indirect sideway view in a scene. Western artists are inclined to capture a specific moment from one fixed standpoint, eastern artists favor to integrate different time and space for a holistic representation which can be best perceived with a floating view. Overall, it seems that western artists tend to represent what they 'see' on their retina or visual cortex and try to make what they paint as real as possible, and eastern artists tend to represent what they 'assume' in their brain ---- showing a strong top-down modulation to what they 'see'.

Historical forerunners of contemporary perspectives in the field of neuroaesthetics

Enrico Giora
Neuroaesthetics is an emerging field of research focused on the idea to pair the psychological experience of artworks with the concomitant neural states, in search of the physiological processes underlying our sense of beauty. The bridge that is often assumed to exist between those heterogeneous areas consists in the hypothesis of common perceptual mechanisms responsible for art experience. Although an involvement of perceptual processes in aesthetic appreciation is widely reasonable, it is nevertheless difficult for this perspective to account for the unbroken changes of styles occurred throughout the history of art, which seem more easily ascribable to culture and subjective taste than to physiological constraints. At the end of the XIX century, art historians and psychologists such as Alois Riegl, Heinrich Wölfflin and Theodor Lipps, have already debated about the role played by sensory and psychological processes in aesthetic experience, referring in particular to the case of visual art. In this contribution we provide a critical review of the ideas of those Authors and we discuss them in respect to the opinions present today in psychology of art and neuroaesthetics.

Neuroaesthetics of ambiguous art: viewing Arcimboldo's artworks

Maddalena Boccia, Federico Nemmi, Emanuela Tizzani, Cecilia Guariglia, Fabio Ferlazzo, Gaspare Galati and Anna Maria Giannini
Neuroaesthetics is a recent sub-field of investigation in neuroscience. It directs to explain neural basis of human appreciation and creation of art. With this study we want to explore a never investigated aspect in neuroaesthetics: the role of perceptual ambiguity in artworks on the neural basis of aesthetic appreciation. With this purpose, a group of 20 healthy young subjects were recruited for this study. We chose stimuli with different degree of ambiguity and art characteristic: 32 Arcimboldo's artworks, 32 renaissance portraits, 32 ambiguous non-artworks and 32 faces. Ambiguous stimuli (both artworks and not) are characterized by a whole-part ambiguity (as well as in Arcimboldo's). Using a mixed fMRI paradigm we ask to subject to judge the stimuli both in an objective condition (artwork or not) both within their aesthetic appreciation (like it or not). Results from principal contrast show that viewing ambiguous artworks in an aesthetic condition (like it or not) activated inferior frontal gyrus bilaterally, middle temporal and middle occipital gyrus in the left hemisphere, fusifor gyrus, inferior temporal gyrus and angular gyrus in the right hemisphere. Results confirm the hypothesis of a particular role of ambiguity viewing artworks, showing different neural activation for ambiguous artworks.

Chinese calligraphy: strokes in motion

JŽr™me Pelletier and Yolaine Escande
In a Chinese calligraphy, traces of the brush are not seen by Chinese calligraphers as separations or boundaries either between the strokes themselves or between the strokes and the surface. Despite the blank spaces between strokes and dots, the strokes and dots that form a Chinese character are seen by Chinese calligraphers inter-related, not only between them, but also with the blank spaces of the paper. Since all these various strokes are produced in a sequence of creative gestures with a brush, ink and water on a sheet of paper, our hypothesis is that their phenomenal unity results from a vicarious kind of re-experiencing done by the viewer of the strokes in motion. We bring in two kinds of elements to make our point: the 'physiological' type and the 'characterological' type of vocabulary used by calligraphers to describe their creations as well as some results of a behavioral experiment showing that movements are perceived by naïve subjects looking at Chinese calligraphy.

Ansel Adams Zone System: Techniques for rendering HDR scenes on LDR film media

John McCann and Alessandro Rizzi
The Ansel Adams Zone System, first described in 1949, was a two-step process that described techniques for scene capture and spatial manipulation of the rendered image [Adams, 1981]. The exposures of the film negative was calculated from spot-photometer scene measurements that determined the scene range. That range determined both the camera exposure and the development procedure in order to capture the entire scene range in the negative. Prints have a very limited range, so spatial dodging and burning techniques compressed the scene information into the rendition range. This work describes the Adam's Zone System and the parallel process of our human vision system to capture dynamic range of natural scenes. In particular the work focuses on the parallels with the High-Dynamic Range (HDR) rod/cone response and the LDR range of ganglion cells. Both the Zone System and human vision underline the important distinction of actual and apparent dynamic range of luminance.