Computer simulations of a neural network model of I-D and 2-D brightness phenomena are presented. The simulations indicate how configural image properties trigger interactions among spatially organized contrastive, boundary segmentation, and filling-in processes to generate emergent percepts. They provide the first unified mechanistic explanation of this set of phenomena, a number of which have received no previous mechanistic explanation. Network interactions between a Boundary Contour (BC) System and a Feature Contour (FC) System comprise the model. The BC System consists of a hierarchy of contrast-sensitive and orientationally tuned interactions, leading to a boundary segmentation. On and off geniculate cells and simple and complex cortical cells are modeled. Output signals from the BC System segmentation generate compartmental boundaries within the FC System. Contrast-sensitive inputs to the FC System generate a lateral filling-in of activation within FC System compartments. The filling-in process is defined by a nonlinear diffusion mechanism. Simulated phenomena include network responses to stimulus distributions that involve combinations of luminance steps, gradients, cusps, and corners of various sizes. These images include impossible staircases, bull's-eyes, nested combinations of luminance profiles, and images viewed under nonuniform illumination conditions. Simulated phenomena include variants of brightness constancy, brightness contrast, brightness assimilation, the Craik-O'Brien-Cornsweet effect, the Koffka-Benussi ring, the Kanizsa-Minguzzi anomalous brightness differentiation, the Hermann grid, and a Land Mondrian viewed under constant and gradient illumination that cannot be explained by retinex theory.

Perception of gaze direction depends not only on the position of the irises within the looker's eyes but also on the orientation of the looker's head. A simple analysis of the geometry of gaze direction predicts this dependence. This analysis is applied to explain the Wollaston effect, the Mona Lisa effect, and the newly presented Mirror gaze effect. In an experiment synthetic faces were used in which the position of the iris and the angle of head rotation were varied. Different groups of subjects judged iris position, head rotation, and gaze direction of the same stimuli. The results illustrate how cues of iris location and head orientation interact to determine perceived gaze direction.

Vibrating membranes are the cornerstone of acoustic technology, forming the backbone of modern loudspeakers and microphones. Acoustic performance of condenser microphone is derived mainly from the membrane's size and achievable static tension. The widely studied and available nickel has been the one of dominant membrane material for several decades.In this paper we introduce multilayer graphene as membrane material for a condenser microphone.The graphene device outperforms a high end commercial nickel-based microphone over a significant part of the acoustic spectrum, with a larger than 10 dB enhancement of sensitivity. Our 2 experimental results are supported with numerical simulations, which show that a 300 layer thick graphene membrane under maximum tension would offer excellent extension of the frequency range, up to 1 MHz, with similar sensitivity as commercial condenser microphones.1.

The lightness of a test patch completely surrounded by an inducing field can be predicted by variants of Wallach's ratio rule. When a patch is surrounded by two or more regions with different luminances, a plausible extension of the ratio rule would predict that the effect of the surrounding regions should correlate with the length of the border they share with the test patch. However, as shown by the Wertheimer-Benary and White effects, lightness of such patches can depart appreciably from these predictions. It is argued that a fruitful approach toward the explanation of such effects is based on the analysis of junctions (such as T-junctions and X-junctions) between regions. Several new displays and variations of old displays involving such junctions are used to illustrate this approach. An alternative analysis of a lightness effect introduced by Adelson is provided, and the role of depth effects in achromatic perception is discussed. A number of limitations of the approach and possible ways to overcome them are noted.

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The perception of a looker's gaze direction depends not only on iris eccentricity (the position of the looker's irises within the sclera) but also on the orientation of the lookers' head. One among several potential cues of head orientation is face eccentricity, the position of the inner features of the face (eyes, nose, mouth) within the head contour, as viewed by the observer. For natural faces this cue is confounded with many other head-orientation cues, but in schematic faces it can be studied in isolation. Salient novel illustrations of the effectiveness of face eccentricity are 'Necker faces', which involve equal iris eccentricities but multiple perceived gaze directions. In four experiments, iris and face eccentricity in schematic faces were manipulated, revealing strong and consistent effects of face eccentricity on perceived gaze direction, with different types of tasks. An additional experiment confirmed the 'Mona Lisa' effect with this type of stimuli. Face eccentricity most likely acted as a simple but robust cue of head turn. A simple computational account of combined effects of cues of eye and head turn on perceived gaze direction is presented, including a formal condition for the perception of direct gaze. An account of the 'Mona Lisa' effect is presented.

The paper addresses the shift in architectural education regarding the need to develop new approaches in teaching methodology, improve curricula, and make advancements in new learning arenas and digital environments. The research is based on the assumption that online workshops could offer a unique learning experience for students in higher education. Accordingly, workshops are considered an essential element in teaching emergency design. As a result, this can produce broader and more innovative solutions to COVID-19 challenges regarding social distancing, limited movements, regulated use of public space, and suspended daily activities. The theoretical notions of emergency design and education for sustainable design enabled the identification of research perspectives and spatial levels to be taken as a starting point of the workshop “COVID-19 Challenges: Architecture of Pandemic” that was conducted by the University of Belgrade—Faculty of Architecture in April 2020. The critical review of the workshop’s procedural and substantial aspects led to identifying four main COVID-19 design challenges perceived in performance, innovation, alteration, and inclusion. Additionally, the paper’s findings concern the identification of learning potentials and limitations arising from a current topic affecting global society, for which neither solutions nor adequate answers in the field of architecture and urbanism have been found.

The illumination interpretation approach claims that lightness illusions can be explained as misapplications of lightness constancy mechanisms, processes which usually enable veridical extraction of surface reflectance from luminance distributions by discounting illumination. In particular, luminance gradients are thought to provide cues about the interactions of light and surfaces. Several examples of strong lightness illusions are discussed for which explanations based on illumination interpretation can be proposed. In criticisms of this approach, a variety of demonstrations of similarly structured control displays are presented, which involve equivalent lightness effects that cannot readily be accounted for by illumination interpretation mechanisms. Furthermore, a number of known and novel displays are presented that demonstrate effects of gradients on the qualitative appearance of uniform regions. Finally, some simple simulations of neural effects of luminance distributions are discussed.