The hierarchy of directional interactions in visual motion processing

It is well known that context influences our perception of visual motion direction. For example, spatial and temporal context manipulations can be used to induce two well-known motion illusions: direction repulsion and the direction after-effect (DAE). Both result in inaccurate perception of direction when a moving pattern is either superimposed on (direction repulsion), or presented following adaptation to (DAE), another pattern moving in a different direction. Remarkable similarities in tuning characteristics suggest that common processes underlie the two illusions. What is not clear, however, is whether the processes driving the two illusions are expressions of the same or different neural substrates. Here we report two experiments demonstrating that direction repulsion and the DAE are, in fact, expressions of different neural substrates. Our strategy was to use each of the illusions to create a distorted perceptual representation upon which the mechanisms generating the other illusion could potentially operate. We found that the processes mediating direction repulsion did indeed access the distorted perceptual representation induced by the DAE. Conversely, the DAE was unaffected by direction repulsion. Thus parallels in perceptual phenomenology do not necessarily imply common neural substrates. Our results also demonstrate that the neural processes driving the DAE occur at an earlier stage of motion processing than those underlying direction repulsion.

The use of cues for attention in ancient Greek art: aspects that influence concentration in the work of art and its elements

The goal of this study is to identify cues for the cognitive process of attention in ancient Greek art, aiming to find confirmation of its possible use by ancient Greek audiences and artists. Evidence of cues that trigger attention’s psychological dispositions was searched through content analysis of image reproductions of ancient Greek sculpture and fine vase painting from the archaic to the Hellenistic period - ca. 7th -1st cent. BC. Through this analysis, it was possible to observe the presence of cues that trigger orientation to the work of art (i.e. amplification, contrast, emotional salience, simplification, symmetry), of a cue that triggers a disseminate attention to the parts of the work (i.e. distribution of elements) and of cues that activate selective attention to specific elements in the work of art (i.e. contrast of elements, salient color, central positioning of elements, composition regarding the flow of elements and significant objects). Results support the universality of those dispositions, probably connected with basic competencies that are hard-wired in the nervous system and in the cognitive processes.

The Fraternity of Metaphors: Jean-Luc Godard's Film Socialisme

Since the 'completion' of Histoire(s) du cinema (1988-1998), Jean-Luc Godard's work has become increasingly mosaic-like in its forms and configurations, and markedly elegiac in its ruminations on history, cinema, art, and thought. While his associative aesthetic and citational method –including his choice of ‘actors’, and the fragmentariness of his ‘soundtracks’ – can combine to create a distinctive cinematic event, the films themselves refuse to cohere around a unifying concern, or yield to a thematic schema. Not surprisingly, Film Socialisme does not offer us the illusion of narrative or structural integrity anymore than it contributes to the quotidian rhetoric of political and moral argument. It is, however, a political film in the sense that it alters something more fundamental than opinions and points of view. It transforms a way of seeing and understanding reality and history, fiction and documentary, images, and images of images. If anything, it belongs to that dissident or ‘dissensual’ category of artwork capable of ‘emancipating the spectator’ by disturbing what Jacques Rancière terms ‘the distribution of the sensible’ in that it generates gaps, openings, and spaces, poses questions, invites associations without positing a fixed position, imposing an interpretation, or allowing itself to invest in the illusion of expressive objectivity and the stability of meaning. The myriad citations and fragments that comprise the film are never intended to culminate into anything cohesive, never mind conclusive. In one sense, they have no source and no context beyond their moment in the film itself, and what we make of that moment. This article studies the degree to which Godard allows these images and sounds to combine and collide, associate and dissolve in this film, arguing that Film Socialisme is both an important intervention in the history of contemporary cinema, and necessary point of reference in any serious discussion of the relations between that cinema and political reality.

A STRUCTURE-FROM-MOTION SCHEME THAT LOOKS FOR PARALLELS, AND ITS IMPLICATIONS FOR APPARENT REVERSALS IN ROTATING TRAPEZIA

Apparent reversals in rotating trapezia have been regarded as evidence that human vision favours methods which are heuristic or form dependent. However, the argument is based on the assumption that general algorithmic methods would avoid the illusion, and that has never been clear. A general algorithm for interpreting moving parallels has been developed to address the issue. It handles a considerable range of stimuli successfully, but finds multiple interpretations in situations which correspond closely to those where apparent reversals occur. This strengthens the hypothesis that apparent reversals may occur when general algorithmic methods fail and heuristics are invoked as a stopgap.

The Quest for Fictionality: Prostitution and Metatextuality in Rachilde’s Monsieur Vénus

This article considers the theme of prostitution in the decadent writings of the fin-de-siecle French author, Rachilde. It proposes that an analysis of this critically-neglected trope of her work reveals new connections between the erotics and aesthetics of her fiction. As a vector for considering tensions between fantasy and truth, and illusion and reality, prostitution, in Rachilde's texts, invites us to reflect on two of the most common cultural manifestations of decadence: sexual non-conformism and the cult of artifice. The article focuses in particular on the (male) prostitute-body of Monsieur Venus, arguing that, in its transcendence of nature, reality and utilitarian purpose, it is elevated to the status of art in Rachilde's fictional world.

Successful balance training is associated with improved multisensory function in fall-prone older adults

Balance maintenance relies on a complex interplay between many different sensory modalities. Although optimal multisensory processing is thought to decline with ageing, inefficient integration is particularly associated with falls in older adults. We investigated whether improved balance control, following a novel balance training intervention, was associated with more efficient multisensory integration in older adults, particularly those who have fallen in the past. Specifically, 76 healthy and fall-prone older adults were allocated to either a balance training programme conducted over 5 weeks or to a passive control condition. Balance training involved a VR display in which the on-screen position of a target object was controlled by shifts in postural balance on a Wii balance board. Susceptibility to the sound-induced flash illusion, before and after the intervention (or control condition), was used as a measure of multisensory function. Whilst balance and postural control improved for all participants assigned to the Intervention group, improved functional balance was correlated with more efficient multisensory processing in the fall-prone older adults only. Our findings add to growing evidence suggesting important links between balance control and multisensory interactions in the ageing brain and have implications for the development of interventions designed to reduce the risk of falls.

Various Joyful Encounters with the Dystopias of Affective Capitalism

This article contends that what appear to be the dystopic conditions of affective capitalism are just as likely to be felt in various joyful encounters as they are in atmospheres of fear associated with post 9/11 securitization. Moreover, rather than grasping these joyful encounters with capitalism as an ideological trick working directly on cognitive systems of belief, they are approached here by way of a repressive affective relation a population establishes between politicized sensory environments and what Deleuze and Guattari (1994) call a brain-becoming-subject. This is a radical relationality (Protevi, 2010) understood in this context as a mostly nonconscious brain-somatic process of subjectification occurring in contagious sensory environments populations become politically situated in. The joyful encounter is not therefore merely an ideological manipulation of belief, but following Gabriel Tarde (as developed in Sampson, 2012), belief is always the object of desire. The discussion starts by comparing recent efforts by Facebook to manipulate mass emotional contagion to a Huxleyesque control through appeals to joy. Attention is then turned toward further manifestations of affective capitalism; beginning with the so-called emotional turn in the neurosciences, which has greatly influenced marketing strategies intended to unconsciously influence consumer mood (and choice), and ending with a further comparison between encounters with Nazi joy in the 1930s (Protevi, 2010) and the recent spreading of right wing populism similarly loaded with political affect. Indeed, the dystopian presence of a repressive political affect in all of these examples prompts an initial question concerning what can be done to a brain so that it involuntarily conforms to the joyful encounter. That is to say, what can affect theory say about an apparent brain-somatic vulnerability to affective suggestibility and a tendency toward mass repression? However, the paper goes on to frame a second (and perhaps more significant) question concerning what can a brain do. Through the work of John Protevi (in Hauptmann and Neidich (eds.), 2010: 168-183), Catherine Malabou (2009) and Christian Borch (2005), the article discusses how affect theory can conceive of a brain-somatic relation to sensory environments that might be freed from its coincidence with capitalism. This second question not only leads to a different kind of illusion to that understood as a product of an ideological trick, but also abnegates a model of the brain which limits subjectivity in the making to a phenomenological inner self or Being in the world.

Modulation of pain threshold by virtual body ownership

Background Appropriate sensorimotor correlations can result in the illusion of ownership of exogenous body parts. Nevertheless, whether and how the illusion of owning a new body part affects human perception, and in particular pain detection, is still poorly investigated. Recent findings have shown that seeing one’s own body is analgesic, but it is not known whether this effect is transferable to newly embodied, but exogenous, body parts. In recent years, results from our laboratory have demonstrated that a virtual body can be felt as one’s own, provided realistic multisensory correlations. Methods The current work aimed at investigating the impact of virtual body ownership on pain threshold. An immersive virtual environment allowed a first-person perspective of a virtual body that replaced the own. Passive movement of the index finger congruent with the movement of the virtual index finger was used in the “synchronous” condition to induce ownership of the virtual arm. The pain threshold was tested by thermal stimulation under four conditions: 1) synchronous movements of the real and virtual fingers, 2) asynchronous movements, 3) seeing a virtual object instead of an arm, and 4) not seeing any limb in real world. Results Our results show that, independently of attentional and stimulus adaptation processes, the ownership of a virtual arm per se can significantly increase the thermal pain threshold. Conclusions This finding may be relevant for the development and improvement of digital solutions for rehabilitation and pain treatment.

Integrated multi-scale architecture of the cortex with application to computer vision

Tese de dout., Engenharia Electrónica e de Computadores, Faculdade de Ciência e Tecnologia, Universidade do Algarve, 2007

Local object gist: meaningful shapes and spatial layout at a very early stage of visual processing

In his introduction, Pinna (2010) quoted one of Wertheimer’s observations: “I stand at the window and see a house, trees, sky. Theoretically I might say there were 327 brightnesses and nuances of color. Do I have ‘327’? No. I have sky, house, and trees.” This seems quite remarkable, for Max Wertheimer, together with Kurt Koffka and Wolfgang Koehler, was a pioneer of Gestalt Theory: perceptual organisation was tackled considering grouping rules of line and edge elements in relation to figure-ground segregation, i.e., a meaningful object (the figure) as perceived against a complex background (the ground). At the lowest level – line and edge elements – Wertheimer (1923) himself formulated grouping principles on the basis of proximity, good continuation, convexity, symmetry and, often forgotten, past experience of the observer. Rubin (1921) formulated rules for figure-ground segregation using surroundedness, size and orientation, but also convexity and symmetry. Almost a century of research into Gestalt later, Pinna and Reeves (2006) introduced the notion of figurality, meant to represent the integrated set of properties of visual objects, from the principles of grouping and figure-ground to the colour and volume of objects with shading. Pinna, in 2010, went one important step further and studied perceptual meaning, i.e., the interpretation of complex figures on the basis of past experience of the observer. Re-establishing a link to Wertheimer’s rule about past experience, he formulated five propositions, three definitions and seven properties on the basis of observations made on graphically manipulated patterns. For example, he introduced the illusion of meaning by comics-like elements suggesting wind, therefore inducing a learned interpretation. His last figure shows a regular array of squares but with irregular positions on the right side. This pile of (ir)regular squares can be interpreted as the result of an earthquake which destroyed part of an apartment block. This is much more intuitive, direct and economic than describing the complexity of the array of squares.

Before identity, gender and human rights

This is the beginning of an exploration of before as the thesis ‘before’ (temporally) and ‘be-fore’ (spatially) difference. Before denotes the origin and the desired destination. Before (in the double sense of ‘before’ and ‚be-in-the-fore’) opens up a space of pre-difference, of origin and of forgotten memory, as well as a space of desire, objective, illusion of teleology, unity, completion. Applied to the two domains of Human Rights and Sex/Gender, the space of ‘before’ yields two slightly different vistas: in human rights, a premodern, functionally undifferentiated society which had to invent human rights as its safeguards of functional differentiation. In Sex/Gender, 'before' brings a self-referential construction: that of ipseity, as the form of identity beyond comparison that does not play with id but with ipsum. Ipseity is inoperable but not useless. It is inoperable because it cannot be observed from anywhere without suffering rupture. It is not useless because it offers a ground for the reconceptualisation of difference, both through awe and desire.