Cortical Dynamics of 3-D Vision and Figure-Ground Pop-Out

Air Force Office of Scientific Research (90-0175); Defense Advanced Research Projects Agency (90-0083); Office of Naval Research (N00014-91-J-4100)

Interocular transfer in perceptual learning of a pop-out discrimination task.

The specificity of the improvement in perceptual learning is often used to localize the neuronal changes underlying this type of adult plasticity. We investigated a visual texture discrimination task previously reported to be accomplished preattentively and for which learning-related changes were inferred to occur at a very early level of the visual processing stream. The stimulus was a matrix of lines from which a target popped out, due to an orientation difference between the three target lines and the background lines. The task was to report the global orientation of the target and was performed monocularly. The subjects' performance improved dramatically with training over the course of 2-3 weeks, after which we tested the specificity of the improvement for the eye trained. In all subjects tested, there was complete interocular transfer of the learning effect. The neuronal correlate of this learning are therefore most likely localized in a visual area where input from the two eyes has come together.

A study on the effects of routing symbol design on process model comprehension

Process modeling grammars are used to create models of business processes. In this paper, we discuss how different routing symbol designs affect an individual's ability to comprehend process models. We conduct an experiment with 154 students to ascertain which visual design principles influence process model comprehension. Our findings suggest that design principles related to perceptual discriminability and pop out improve comprehension accuracy. Furthermore, semantic transparency and aesthetic design of symbols lower the perceived difficulty of comprehension. Our results inform important principles about notational design of process modeling grammars and the effective use of process modeling in practice.

Boundary, Brightness, and Depth Interactions During Preattentive Representation and Attentive Recognition of Figure and Ground

This article applies a recent theory of 3-D biological vision, called FACADE Theory, to explain several percepts which Kanizsa pioneered. These include 3-D pop-out of an occluding form in front of an occluded form, leading to completion and recognition of the occluded form; 3-D transparent and opaque percepts of Kanizsa squares, with and without Varin wedges; and interactions between percepts of illusory contours, brightness, and depth in response to 2-D Kanizsa images. These explanations clarify how a partially occluded object representation can be completed for purposes of object recognition, without the completed part of the representation necessarily being seen. The theory traces these percepts to neural mechanisms that compensate for measurement uncertainty and complementarity at individual cortical processing stages by using parallel and hierarchical interactions among several cortical processing stages. These interactions are modelled by a Boundary Contour System (BCS) that generates emergent boundary segmentations and a complementary Feature Contour System (FCS) that fills-in surface representations of brightness, color, and depth. The BCS and FCS interact reciprocally with an Object Recognition System (ORS) that binds BCS boundary and FCS surface representations into attentive object representations. The BCS models the parvocellular LGN→Interblob→Interstripe→V4 cortical processing stream, the FCS models the parvocellular LGN→Blob→Thin Stripe→V4 cortical processing stream, and the ORS models inferotemporal cortex.

Preattentive Texture Segmentation and Grouping by the Boundary Contour System

An improved Boundary Contour System (BCS) neural network model of preattentive vision is applied to two images that produce strong "pop-out" of emergent groupings in humans. In humans these images generate groupings collinear with or perpendicular to image contrasts. Analogous groupings occur in computer simulations of the model. Long-range cooperative and short-range competitive processes of the BCS dynamically form the stable groupings of texture regions in response to the images.

3-D Vision and Figure-Ground Separation by Visual Cortex

A neural network theory of :3-D vision, called FACADE Theory, is described. The theory proposes a solution of the classical figure-ground problem for biological vision. It does so by suggesting how boundary representations and surface representations are formed within a Boundary Contour System (BCS) and a Feature Contour System (FCS). The BCS and FCS interact reciprocally to form 3-D boundary and surface representations that arc mutually consistent. Their interactions generate 3-D percepts wherein occluding and occluded object completed, and grouped. The theory clarifies how preattentive processes of 3-D perception and figure-ground separation interact reciprocally with attentive processes of spatial localization, object recognition, and visual search. A new theory of stereopsis is proposed that predicts how cells sensitive to multiple spatial frequencies, disparities, and orientations are combined by context-sensitive filtering, competition, and cooperation to form coherent BCS boundary segmentations. Several factors contribute to figure-ground pop-out, including: boundary contrast between spatially contiguous boundaries, whether due to scenic differences in luminance, color, spatial frequency, or disparity; partially ordered interactions from larger spatial scales and disparities to smaller scales and disparities; and surface filling-in restricted to regions surrounded by a connected boundary. Phenomena such as 3-D pop-out from a 2-D picture, DaVinci stereopsis, a 3-D neon color spreading, completion of partially occluded objects, and figure-ground reversals are analysed. The BCS and FCS sub-systems model aspects of how the two parvocellular cortical processing streams that join the Lateral Geniculate Nucleus to prestriate cortical area V4 interact to generate a multiplexed representation of Form-And-Color-And-Depth, or FACADE, within area V4. Area V4 is suggested to support figure-ground separation and to interact. with cortical mechanisms of spatial attention, attentive objcect learning, and visual search. Adaptive Resonance Theory (ART) mechanisms model aspects of how prestriate visual cortex interacts reciprocally with a visual object recognition system in inferotemporal cortex (IT) for purposes of attentive object learning and categorization. Object attention mechanisms of the What cortical processing stream through IT cortex are distinguished from spatial attention mechanisms of the Where cortical processing stream through parietal cortex. Parvocellular BCS and FCS signals interact with the model What stream. Parvocellular FCS and magnocellular Motion BCS signals interact with the model Where stream. Reciprocal interactions between these visual, What, and Where mechanisms arc used to discuss data about visual search and saccadic eye movements, including fast search of conjunctive targets, search of 3-D surfaces, selective search of like-colored targets, attentive tracking of multi-element groupings, and recursive search of simultaneously presented targets.

A Solution of the Figure-ground Problem for Biological Vision

A neural network model of 3-D visual perception and figure-ground separation by visual cortex is introduced. The theory provides a unified explanation of how a 2-D image may generate a 3-D percept; how figures pop-out from cluttered backgrounds; how spatially sparse disparity cues can generate continuous surface representations at different perceived depths; how representations of occluded regions can be completed and recognized without usually being seen; how occluded regions can sometimes be seen during percepts of transparency; how high spatial frequency parts of an image may appear closer than low spatial frequency parts; how sharp targets are detected better against a figure and blurred targets are detector better against a background; how low spatial frequency parts of an image may be fused while high spatial frequency parts are rivalrous; how sparse blue cones can generate vivid blue surface percepts; how 3-D neon color spreading, visual phantoms, and tissue contrast percepts are generated; how conjunctions of color-and-depth may rapidly pop-out during visual search. These explanations arise derived from an ecological analysis of how monocularly viewed parts of an image inherit the appropriate depth from contiguous binocularly viewed parts, as during DaVinci stereopsis. The model predicts the functional role and ordering of multiple interactions within and between the two parvocellular processing streams that join LGN to prestriate area V4. Interactions from cells representing larger scales and disparities to cells representing smaller scales and disparities are of particular importance.

Pre-Attentive Segmentation in the Primary Visual Cortex

Stimuli outside classical receptive fields have been shown to exert significant influence over the activities of neurons in primary visual cortexWe propose that contextual influences are used for pre-attentive visual segmentation, in a new framework called segmentation without classification. This means that segmentation of an image into regions occurs without classification of features within a region or comparison of features between regions. This segmentation framework is simpler than previous computational approaches, making it implementable by V1 mechanisms, though higher leve l visual mechanisms are needed to refine its output. However, it easily handles a class of segmentation problems that are tricky in conventional methods. The cortex computes global region boundaries by detecting the breakdown of homogeneity or translation invariance in the input, using local intra-cortical interactions mediated by the horizontal connections. The difference between contextual influences near and far from region boundaries makes neural activities near region boundaries higher than elsewhere, making boundaries more salient for perceptual pop-out. This proposal is implemented in a biologically based model of V1, and demonstrated using examples of texture segmentation and figure-ground segregation. The model performs segmentation in exactly the same neural circuit that solves the dual problem of the enhancement of contours, as is suggested by experimental observations. Its behavior is compared with psychophysical and physiological data on segmentation, contour enhancement, and contextual influences. We discuss the implications of segmentation without classification and the predictions of our V1 model, and relate it to other phenomena such as asymmetry in visual search.

Perceiving Illumination Inconsistencies in Scenes

The human visual system is adept at detecting and encoding statistical regularities in its spatio-temporal environment. Here we report an unexpected failure of this ability in the context of perceiving inconsistencies in illumination distributions across a scene. Contrary to predictions from previous studies [Enns and Rensink, 1990; Sun and Perona, 1996a, 1996b, 1997], we find that the visual system displays a remarkable lack of sensitivity to illumination inconsistencies, both in experimental stimuli and in images of real scenes. Our results allow us to draw inferences regarding how the visual system encodes illumination distributions across scenes. Specifically, they suggest that the visual system does not verify the global consistency of locally derived estimates of illumination direction.

Psychophysische Skalierung visueller Merkmalssalienz

Die Messung der Stärke von Empfindungen hat in der Psychologie eine lange Tradition, die bis in die Zeit der Entstehung der Psychologie als eine eigenständige Wissenschaft gegen Ende des 19. Jahrhunderts zurückreicht. Gustav Theodor Fechner verband die Beobachtung Webers der Konstanz des Koeffizienten des eben merklichen Unterschieds zu der Vergleichsintensität (sog. "Weber-Quotient") mit der Annahme einer sensorischen Schwelle, und entwickelte daraus erstmals eine Skala für die Stärke von Empfindungen. Die Fechner-Skala verwendet die Anzahl sukzessiver Schwellenschritte als natürliche, psychologische Einheit. Die Stärke einer Empfindung für eine gegebene Reizintensität wird ausgedrückt als die Anzahl von Schwellenschritten, die man gehen muss, um von keiner Empfindung bis zur in Frage stehenden Empfindung zu gelangen. Die Funktion, die den Zusammenhang von Reizintensität und der Anzahl nötiger Schwellenschritte beschreibt, ist stets logarithmisch und über sukzessive Schwellenmessungen für Reize aus den verschiedensten Sinnesmodalitäten bestimmbar. Derart sich ergebende Skalierungen heißen "indirekt", weil die in Frage stehende Reizintensität selbst nicht von der Urteilsperson bewertet wird. Intensitäten sind vom Urteiler nur mit anderen Intensitäten in Bezug auf ein "stärker" oder "schwächer", also ordinal, zu vergleichen. Indirekte Skalierungsmethoden eignen sich insbesondere, wenn der Reizeindruck flüchtig und von der absoluten Stärke her schwer durch den Urteiler zu quantifizieren ist. Ein typisches Beispiel hierfür ist die Auffälligkeit (Salienz) von visuellen Objekten, die in zufällig wechselnde Hintergründe eingebettet sind und dem Betrachter nur als ein rasches raumzeitliches Aufblitzen präsentiert werden. Die Stärke des Unterschieds in Merkmalen wie Helligkeit, Farbe, Orientierung, Schattierung, Form, Krümmung, oder Bewegung bestimmt das Ausmaß der Salienz von Objekten. Obschon eine Fülle von Arbeiten existiert zu der Frage, welche Merkmale und deren Kombinationen ohne Wissen des Ortes ihrer Präsentation automatisch starke Salienz ("Pop-Out") erzeugen, existieren bislang keine systematischen Versuche, die Salienz von Merkmalen für einen weiten Bereich von Merkmalsunterschieden zu erfassen und vergleichbar zu machen. Indirekte Skalierungen liegen vor für die Merkmale Kontrast (Legge und Foley, 1980) und Orientierung (Motoyoshi und Nishida, 2001). Ein Vergleich der Salienz über mehrere Merkmale und der Nachweis, dass die Salienz eine eigene, von der Merkmalsdimension unabhängige sensorische Qualität ist, steht aber bislang aus. In der vorliegenden Arbeit wird gezeigt, dass der Unterschied von Objekten zur einbettenden Umgebung hinsichtlich visueller Merkmale zu Salienz führt und diese Salienz unabhängig von dem sie erzeugenden Merkmal der Stärke nach skalierbar ist. Es wird ferner gezeigt, dass die Einheiten der für zwei Merkmale erhobenen indirekten Skalierungsfunktionen in einem absoluten Sinne gleich sind, solange sichergestellt ist, dass (i) keine alternativen Hinweisreize existieren und nur der reine Merkmalsunterschied von Objekt und Umgebung bewertet wird und (ii) das sensorische Rauschen in den aktivierten Merkmalskanälen für beide Merkmale gleich ist. Für diesen Aufweis wurden exemplarisch die Merkmale Orientierung und Ortsfrequenz ausgewählt und die Salienz ihrer Merkmalskontraste über Naka-Rushton-Funktionen, gewonnen aus den zugrundeliegenden Salienz-Inkrementschwellenmessungen, indirekt skaliert. Für das Merkmal Ortsfrequenz liegt hiermit erstmals eine indirekte Skalierung vor. Hierfür musste eine spezielle Messtechnik entwickelt werden, die die Bewertung reiner Ortsfrequenzunterschiede, frei von konfundierenden absoluten Ausprägungen der Ortsfrequenzen, sicherstellt. Die Methode ist in Kapitel 7 dargestellt. Experimente, die die konfundierende Wirkung absoluter Merkmalsausprägungen auf die Salienzmessung demonstrieren, sind in Kapitel 6 dargestellt. In Kapitel 8 findet sich ein empirischer Abgleich der Ergebnisse von Inkrement- und Dekrementschwellenmessungen, eine Messtechnik, die zur Erfassung von Unterschiedsschwellen im Extrembereich der Orientierungsunterschiede von 90° nötig ist. Kapitel 9 enthält den empirischen Aufweis der Transitivität der Gleichheitsrelation für Salienzmessungen von Orientierung und Ortsfrequenz durch Abgleich mit einem dritten Merkmal und erbringt damit den Beleg der merkmalsunabhängigen Erfassung von Auffälligkeit über die indirekte Skalierungsmethodik. Ferner wird dort die Wirksamkeit der Grundsalienz von Mustern, gegeben über externes Rauschen in den Merkmalen (sog. "Merkmalsjitter") für die Verschiebung des Nullpunktes der Skalierungsfunktion aufgezeigt. Im letzten Experiment (Kapitel 10) wird dann die Skalierung von Orientierung und Ortsfrequenz bei gleicher Grundsalienz der Muster verglichen und gezeigt, dass beide Skalen in einem absoluten Sinne gleiche Einheiten aufweisen (also gleiche Skalenzahlen gleiche sensorische Auffälligkeiten anzeigen, obwohl sie von verschiedenen Merkmalen stammen), wenn der Effekt des sensorischen Rauschens, der im Merkmal Orientierung nicht über die verschiedenen Schwellenschritte konstant ist, kompensiert wird. Die Inkonstanz des Effektes des sensorischen Rauschens im Merkmal Orientierung wird über die Veränderung der Steigung der psychometrischen Präferenzfunktion für die Vergleichsurteile der Orientierungssalienz für eine fest vorgegebene Ortsfrequenzsalienz greifbar, und der Effekt der Steigungsveränderung kompensiert exakt die Nichtlinearität in der für beide Merkmale erhobenen Salienz-Matchingfunktion. Im letzten Kapitel wird ein Ausblick auf eine mögliche Modellierung der Salienzfunktionen über klassische Multikanal-Feedforwardmodelle gegeben. In den ersten fünf Kapiteln sind einführend die Gebiete der indirekten Skalierung, der Merkmalssalienz und der Texturtrennung im menschlichen visuellen System dargestellt.

Deformation Studies of Tungsten-Gold Contacts at the Nanometer Scale.

The deformation behavior of atomically clean, nanometer sized tungsten / gold contacts was studied at room temperature in ultra-high vacuum. An instrument that combines atomic force microscopy (AFM), scanning tunneling microscopy (STM), and field ion microscopy (FIM) into a single experimental apparatus was designed, constructed, and calibrated. A cross-hair force sensor having a spring constant of - 442 N/m was developed and its motion was monitored during indentation experiments with a differential interferometer. Tungsten tips of controlled size (12.8 nm < tip radius < 2 1.6 nm) were first shaped and characterized using FIM and then indented into a Au (1 10) single crystal to depths ranging from 1.5 nrn to 18 nm using the force sensor. Continuum mechanics models were found to be valid in predicting elastic deformation during initial contact and plastic zone depths despite our small size regime. Multiple discrete yielding events lasting < 1.5 ms were observed during the plastic deformation regime; at the yield points a maximum value for the principal shear stress was measured to be 5 + 1 GPa. During tip withdrawal, "pop-out" events relating to material relaxation within the contact were observed. Adhesion between the tip and sample led to experimental signatures that suggest neck formation prior to the break of contact. STM images of indentation holes revealed various shapes that can be attributed to the (1 1 1 ) (1 10) crystallographic slip system in gold. FIM images of the tip after indentation showed no evidence of tip damage

Music for the Pria Dewasa : changes and continuities in class and pop music genres

This paper presents Rolling Stone Indonesia (RSI) and places it in an historical context to tease out some changes and continuities in Indonesian middle-class politics since the beginning of the New Order. Some political scientists have claimed that class interests were at the core of the transition from Guided Democracy to the New Order, and popular music scholars generally assert that class underlies pop genre distinctions. But few have paid attention to how class and genre were written into Indonesian pop in the New Order period; Indonesian pop has a fascinating political history that has so far been overlooked. Placing RSI in historical perspective can reveal much about the print media’s classing of pop under New Order era political constraints, and about the ways these modes of classing may or may not have endured in the post-authoritarian, globalised and liberalised media environment.

‘Pop Melayu vs. Pop Indonesia: Marketeers, producers and new interpretations of a genre into the 2000s’ in Sonic Modernities in Southeast Asia Leiden: Brill pp. 187- 215

Kangen Band, as an example of reclaiming of the derisive term kampungan. In it, I argue that this reclaiming represents an interesting case of genre manipulation, and consider what this can reveal about how Indonesian pop genres are constituted, what they ‘are’ and what they ‘do’. In so doing, I seek to rework existing scholarship relating to Indonesian pop genres and modernity, as well as interrogate some broader theories of genre. In this essay, I extend the argument that Indonesian pop genres are not purely technical categories, they touch on myths of class and nation (Wallach 2008; Weintraub 2010; Yampolsky 1989. As we shall see, in the New Order period, pop music genres reached out to these myths by positioning themselves variously vis-à-vis the capital city, Jakarta. Such positioning, achieved through use of the terms gedongan (a term that strives to infer refinement by stressing the non-masses’ central position in the urban environment) and kampungan (a term that strives to enforce subalterns’ marginal position in relation to the metropolis, see also the previous contribution by Weintraub), continues to haunt the constitution of genre in the post-New Order period, but in novel ways. These novel ways, I argue, may be seen to result from industrial transformation and new systems of knowledge production.

Cosmopatriatism in Indonesian pop music imagings

In this article, cosmopatriotism is seen to describe an effect of transnational capitalism’s need to “settle down” in particular localities. The self-imaging of female singer Krisdayanti and punk band Superman is Dead serve as agentive forces in the working out of novel, post-New Order modernities. The body, in particular, is an important site to inscribe a sense of authenticity and social mobility, as well as to work out a sense of post-Suharto Indonesian-ness.

Characterization of two membrane-associated protease genes obtained from screening out-membrane protein genes of Flavobacterium columnare G(4)

In order to identify genes encoding the outer membrane proteins (OMPs) of the myxobacter Flavobacterium columnare G(4), the expression library of the bacterium was screened by using rabbit antisera developed against its OMPs. Positive colonies of Escherichia coli M15 containing fragments encoding the bacterial OMPs were selected for cloning the relevant genes by genomic walking methods. Two genes encoding a membrane-associated zinc metalloprotease and prolyl oligopeptidase are reported in this paper. The membrane-associated zinc metalloprotease gene (map) is 1800 bp in length, coding for 449 amino acids (aa). Despite the presence of a conserved motif HEXXH for all metalloproteases, the special HEXXH similar to 32 aa similar to E motif of the F. columnare G(4) Map and its low level of identity with other reported zinc-containing metalloproteases may imply that the membrane-associated zinc metalloprotease of F. columnare G(4) represents a new family of zincins. The gene encoding prolyl oligopeptidase (Pop), a serine proteinase, is 2352 bp in length, coding for 649 aa. Sequence homology analysis revealed that the Pop is also novel as it has <50% identity with other reported prolyl oligopeptidase family proteins. The present study represents the first to employ anti-fish bacterial OMP sera to screen genes of membrane-associated proteases of fish pathogenic bacteria, and to provide necessary information for the examination of the role of the two genes in the infection and pathogenesis of F. columnare.