Manish Singh

Manish Singh
Rutgers, The State University of New Jersey | Rutgers · Department of Psychology (New Brunswick)

About

153
Publications
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4,426
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Publications

Publications (153)
Article
Full-text available
We present a novel phenomenon involving an interaction between accretion deletion, figure-ground interpretation, and structure-from-motion. Our displays contain alternating light and dark vertical regions in which random-dot textures moved horizontally at constant speed but in opposite directions in alternating regions. This motion is consistent wi...
Article
Full-text available
Visual estimation of object stability is an ecologically important judgment that allows observers to predict the physical behavior of objects. A natural method that has been used in previous work to measure perceived object stability is the estimation of perceived "critical angle"-the angle at which an object appears equally likely to fall over ver...
Article
This paper investigates the classification of shapes into broad natural categories such as animal or leaf. We asked whether such coarse classifications can be achieved by a simple statistical classification of the shape skeleton. We surveyed databases of natural shapes, extracting shape skeletons and tabulating their parameters within each class, s...
Article
Geometric and neural models of illusory-contour (IC) synthesis currently use only local contour geometry to derive the shape of ICs. Work on the visual representation of shape, by contrast, points to the importance of both contour and surface geometry. We investigated the influence of surface-based geometric factors on IC shape. The local geometry...
Article
We investigated whether observers use rate of change of curvature in visually extrapolating contour shape. Arcs of Euler spirals with positive or negative rate of change of curvature gamma (hence linearly increasing or decreasing curvature) disappeared behind the straight-edge of a half-disk occluder. Observers adjusted the position and the orienta...
Article
Conventional accounts of motion perception mostly treat accretion/deletion—the appearance or disappearance of texture at a boundary between regions—as an essentially decisive cue to relative depth: the accreting/deleting surface is interpreted as being behind adjacent surfaces. Under certain circumstances, however, accretion/deletion can be perceiv...
Article
Does natural selection favor veridical percepts—those that accurately (if not exhaustively) depict objective reality? Perceptual and cognitive scientists standardly claim that it does. Here we formalize this claim using the tools of evolutionary game theory and Bayesian decision theory. We state and prove the “Fitness-Beats-Truth (FBT) Theorem” whi...
Article
Full-text available
A theory of consciousness, whatever else it may do, must address the structure of experience. Our perceptual experiences are richly structured. Simply seeing a red apple, swaying between green leaves on a stout tree, involves symmetries, geometries, orders, topologies, and algebras of events. Are these structures also present in the world, fully in...
Article
We investigated the dimensions defining mental shape space, by measuring shape discrimination thresholds along "morph-spaces" defined by pairs of shapes. Given any two shapes, one can construct a morph-space by taking weighted averages of their boundary vertices (after normalization), creating a continuum of shapes ranging from the first shape to t...
Article
Standard accounts of accretion/deletion of texture treat it as a definite cue to depth ordering: The accreting/deleting surface is interpreted as being behind the adjoining surface. Froyen, Feldman, and Singh showed that accretion/deletion can also, under certain circumstances, be perceived as a 3D column rotating in front, with the accretion/delet...
Article
Networks of “conscious agents” (CAs) as defined by Hoffman and Prakash (2014) are shown to provide a robust and intuitive representation of perceptual and cognitive processes in the context of the Interface Theory of Perception (Hoffman, Singh and Prakash, 2015). The behavior of the simplest CA networks is analyzed exhaustively. The construction of...
Article
MOTIVATION. We investigated the dimensions defining mental shape space, by measuring shape discrimination thresholds along "morph-spaces" defined by pairs of shapes. Given any two shapes, one can construct a morph-space by taking weighted averages of their boundary vertices (after normalization), creating a continuum of shapes ranging from the firs...
Article
It is still an unresolved question how the visual system perceives surface lightness given the ambiguity of the sensory input signal. We studied lightness perception using two-dimensional images of variegated checkerboards shown as perspective projections of three-dimensional objects. We manipulated the contrast of a target check relative to its su...
Article
Part- and axis-based approaches organize shape representations in terms of simple parts and their spatial relationships. Shape transformations that alter qualitative part structure have been shown to be more detectable than those that preserve it. We compared sensitivity to various transformations that change quantitative properties of parts and th...
Article
Accretion-deletion is widely considered a decisive cue to surface depth ordering, with the accreting or deleting surface interpreted as behind an adjoining surface. However, Froyen, Feldman, and Singh (2013) have shown that when accretion-deletion occurs on both sides of a contour, accreting-deleting regions can also be perceived as in front and as...
Article
The detection of contours in noise has been extensively studied, but the detection of closed contours, such as the boundaries of whole objects, has received relatively little attention. Closed contours pose substantial challenges not present in the simple (open) case, because they form the outlines of whole shapes and thus take on a range of potent...
Article
We propose that selection favors nonveridical perceptions that are tuned to fitness. Current textbooks assert, to the contrary, that perception is useful because, in the normal case, it is veridical. Intuition, both lay and expert, clearly sides with the textbooks. We thus expected that some commentators would reject our proposal and provide counte...
Article
Perception is a product of evolution. Our perceptual systems, like our limbs and livers, have been shaped by natural selection. The effects of selection on perception can be studied using evolutionary games and genetic algorithms. To this end, we define and classify perceptual strategies and allow them to compete in evolutionary games in a variety...
Article
Human observers can interpret line drawings as well-defined 3D surfaces, despite the absence of local cues to depth such as shading and texture. In our previous work (VSS2013, VSS2014), we found that human depth interpretation in the interior of line drawings is probabilistic, in that the degree of certainty in judgments of relative depth varies in...
Article
Structure-from-motion (SFM) studies have shown that people are good at perceiving 3D structure in dynamic dot displays consistent with rigid object rotation. However, observers can still perceive volumetric structure even when image motion is inconsistent with rigid rotation. As an extreme case, in dynamic figure-ground displays containing textural...
Article
We recently showed that a contrast-based model of lightness perception outperformed a number of other models in predicting lightness matches across different viewing conditions (Zeiner & Maertens, 2014; Maertens & Shapley, 2013). By considering regional variations in contrast range, the model successfully predicted lightness constancy across change...
Article
In this study we investigated the conditions under which the visual system treats negative parts as objects. A negative part is a background region mostly surrounded by a region of negative curvature along a figure's contour. Previous work has shown that negative parts can take on a "quasi-figural" status, inducing globally inconsistent judgments o...
Article
Standard accounts of accretion/deletion treat it as a reliable, self-sufficient cue to depth ordering: the accreting/deleting surface is interpreted as behind the adjoining surface. However accretion/deletion can also result from self-occlusion of a rotating 3D object. When accretion/deletion occurs on both sides of each contour in a multi-region d...
Article
Shape completion is essential for representing the visual world under conditions of partial occlusion. A number of accounts of shape completion have been proposed, some of which entail differences between modal (completing in front) and amodal (completing behind) cases. Our aim in this study was to better understand shape completion in general, to...
Article
It is well-known that ''smooth'' chains of oriented elements-contours-are more easily detected amid background noise than more undulating (i.e., ''less smooth'') chains. Here, we develop a Bayesian framework for contour detection and show that it predicts that contour detection performance should decrease with the contour's complexity, quantified a...
Article
We present a probabilistic approach to shape decomposition that creates a skeleton-based shape representation of a 3D object while simultaneously decomposing it into constituent parts. Our approach probabilistically combines two prominent threads from the shape literature: skeleton-based (medial axis) representations of shape, and part-based repres...
Article
Full-text available
Humans can judge from vision alone whether an object is physically stable or not. Such judgments allow observers to predict the physical behavior of objects, and hence to guide their motor actions. We investigated the visual estimation of physical stability of 3-D objects (shown in stereoscopically viewed rendered scenes) and how it relates to visu...
Conference Paper
We present a probabilistic approach to shape decomposition that creates a skeleton-based shape representation of a 3D object while simultaneously decomposing it into constituent parts. Our approach probabilisti-cally combines two prominent threads from the shape literature: skeleton-based (medial axis) representations of shape, and part-based repre...
Article
We studied the influence of local and global information on the 3D interpretation of line drawings of smooth objects. T-junctions are well known to play an important role in conveying relative depth. In previous studies (VSS2013) we found that (1) local depth ordering from T-junctions is probabilistic, with subjects' interpretation of relative dept...
Article
We propose a novel framework for perceptual grouping based on the idea of mixture models, called Bayesian hierarchical grouping (BHG). In BHG, we assume that the configuration of image elements is generated by a mixture of distinct objects, each of which generates image elements according to some generative assumptions. Grouping, in this framework,...
Chapter
Full-text available
Contours provide an essential source of information about shape and, along contours, points with the greatest magnitude of curvature tend to be most informative. This concentration of information is closely tied to internal generative models of contours employed by the visual system. In going from open to closed contours, the sign of curvature beco...
Article
We present a novel phenomenon involving an interaction between accretion-deletion and figure-ground. Our displays consisted of alternating light and dark regions containing random-dot textures, which moved horizontally at constant speed, but in opposite directions in alternating regions. Due to the ambiguous nature of the accretion-deletion cue (ac...
Presentation
We investigated the detection of shapes (closed contours) in noise as a function of their complexity. As in previous work (VSS2012), we quantified complexity in several ways reflecting alternate shape-generating models. In a contour-based model, complexity is defined as the integrated surprisal along the contour, that is, the summed negative log pr...
Article
Full-text available
Accretion-deletion is widely considered a decisive cue to surface depth ordering, with the accreting or deleting surface interpreted as behind an adjoining surface. However, Froyen, Feldman, and Singh (2013) have shown that when accretion-deletion occurs on both sides of a contour, accreting-deleting regions can also be perceived as in front and as...
Article
Full-text available
When objects collide, human observers perceive not only motion but also causal relations, such as which object caused the other to move. In the present experiments, we investigated whether such causal interpretations can actually influence the perceived path of apparent motion. Displays contained two alternately flashing motion targets positioned a...
Article
Does natural selection favor veridical perceptions, those that more accurately depict the objective environment? Vision researchers often claim that it does. But this claim, though influential, has not been adequately tested. In this paper we formalize the claim and a few alternatives. We then discuss the results of evolutionary games and genetic a...
Chapter
We present a formal framework that generalizes and subsumes the standard Bayesian framework for vision. While incorporating the fundamental role of probabilistic inference, our Computational Evolutionary Perception (CEP) framework also incorporates fitness in a fundamental way, and it allows us to consider different possible relationships between t...
Chapter
We present a unified Bayesian approach to shape representation and related problems in perceptual organization, including part decomposition, shape similarity, figure/ground estimation, and 3D shape. The approach is based on the idea of estimating the skeletal structure most likely to have generated the observed shape via a process of stochastic “g...
Article
Full-text available
When objects collide, observers perceive not only the motion but also causal relations, such as which objects caused which others to move. The present study investigated whether such causal interpretations can influence the perceived path of apparent motion. We presented a display of two alternately flashing motion tokens on the ends of a semicircu...
Article
Full-text available
Marr proposed that human vision constructs "a true description of what is there". He argued that to understand human vision one must discover the features of the world it recovers and the constraints it uses in the process. Bayesian decision theory (BDT) is used in modem vision research as a probabilistic framework for understanding human vision al...
Article
Physical stability is an ecologically important judgment about objects that allows observers to predict object behavior and appropriately guide motor actions to interact with them. Moreover, it is an attribute that observers can estimate from vision alone, based on an object's shape. In previous work, we have used different tasks to investigate per...
Article
We studied the detection of natural shapes embedded in random backgrounds. Detecting coherent objects in cluttered background is a basic function of perceptual organization. Numerous studies have investigated the case of simple open contours, but few have considered the more naturalistic case of complex closed shapes. We studied the detection of na...
Article
We present a novel method for measuring figure-ground assignment, based on the observation that the same disparity signal can yield percepts involving different directions of slant depending on how figure-ground is assigned. In figure-ground stimuli containing alternating black and white strips, near disparity was introduced on every other contour...
Article
Deep indentations in shapes are often perceived as negative parts, i.e., as regions "subtracted" from a base shape (such as a bite taken out of an apple; Hoffman & Richards, 1984). Previous work (Kim & Feldman, 2009) has shown that figure/ground (f/g) assignment can reverse in the vicinity of a negative part. Here we study the conditions that favor...
Article
Detection of simple isolated contours amid random background elements is a basic perceptual capacity, and has been extensively studied. But while simple contours are essential building blocks of object representations, objects and scenes also involve emergent or "Gestalt" configural features that involve nonlocal combinations of contours. Here we i...
Article
A central theme of perceptual theory, from the Gestaltists to the present, has been the integration of local and global image information. While neuroscience has traditionally viewed perceptual processes as beginning with local operators with small receptive fields before proceeding on to more global operators with larger ones, a substantial body o...
Article
Full-text available
In 1912, Max Wertheimer published his paper on phi motion, widely recognized as the start of Gestalt psychology. Because of its continued relevance in modern psychology, this centennial anniversary is an excellent opportunity to take stock of what Gestalt psychology has offered and how it has changed since its inception. We first introduce the key...
Article
Full-text available
Lim and Leek (2012) presented a formalization of information along object contours, which they argued was an alternative to the approach taken in our article (Feldman & Singh, 2005). Here, we summarize the 2 approaches, showing that--notwithstanding Lim and Leek's (2012) critical rhetoric--their approach is substantially identical to ours, except f...
Article
Full-text available
We investigated whether amodal completion can bias apparent motion (AM) to deviate from its default straight path toward a longer curved path, which would violate the well-established principle that AM follows the shortest possible path. Observers viewed motion sequences of two alternating rectangular tokens positioned at the ends of a semicircular...
Article
Full-text available
The question of what are good views of a 3D object has been addressed by numerous researchers in perception, computer vision, and computer graphics. This has led to a large variety of measures for the goodness of views as well as some special-case viewpoint selection algorithms. In this article, we leverage the results of a large user study to opti...
Article
Visual estimation of object stability is an ecologically important judgment that allows observers to predict an object's physical behavior. One way to measure perceived stability is by estimating the "critical angle" (relative to upright) at which an object is perceived to be equally likely to fall over versus return to its upright position. Howeve...
Article
Many influences on figure/ground assignment have been identified, but the influence of shape is poorly understood. Here we investigate the influence of axiality - the degree to which a shape has a clearly articulated skeletal structure - by pitting axiality against a known f/g cue, symmetry. We designed displays in which a multi-part axial shape sh...
Article
A moving object is temporarily invisible as it passes behind an occluding surface, but people perceive it as moving continuously behind the occluder, suggesting that the representation of the moving object is amodally maintained during its disappearance. In this study, we investigated whether amodal representation of a moving object can persist whe...
Article
Shape (both 2D and 3D) and figure/ground organization have usually been treated as disparate topics, but the representation of contour shape and the assignment of border ownership (figure/ground) are well-known to be intimately related. In this work we present Bayesian techniques for estimating them jointly in an integrated fashion. In previous wor...
Article
Most previous studies on figure/ground have employed methods that measure figure/ground (f/g) in a global, explicit manner: most commonly, subjects are simply asked which region appears to be in front. Recently Kim and Feldman (2009) proposed a method that assesses figure/ground indirectly at isolated points along a boundary. In the motion-probe me...
Article
Full-text available
Itis well-known that "smooth" chains of oriented elements-contours-are more easily detected amid background noise than more undulating (i.e., "less smooth") chains. Here, we develop a Bayesian framework for contour detection and show that it predicts that contour detection performance should decrease with the contour's complexity, quantified as the...
Conference Paper
Full-text available
Background / Purpose: The computation of border-ownership (BOWN) and the reconstruction of surface structure — i.e., figure/ground assignment and the interpolation of missing contours — are essential puzzles of visual computation, in part because they epitomize the integration of local and global cues to generate a coherent percept.Here we attemp...
Article
Full-text available
How does the brain estimate object stability? Objects fall over when the gravity-projected centre-of-mass lies outside the point or area of support. To estimate an object's stability visually, the brain must integrate information across the shape and compare its orientation to gravity. When observers lie on their sides, gravity is perceived as tilt...
Article
Visual estimation of object stability is an ecologically important judgment that allows observers to predict objects' physical behavior. Previously we have used the 'critical angle' of tilt to measure perceived object stability (VSS 2010; VSS 2011). The current study uses a different paradigm -- measuring the critical extent to which an object can...
Article
Full-text available
We developed a method analogous to classification images that allowed us to measure the influence that each dot in a dot cluster had on observers' estimates of the center of the cluster. In Experiment 1, we investigated whether observers employ a robust estimator when estimating the centers of dot clusters that were drawn from a single distribution...
Article
Purpose: We studied the mental representation of shape using a novel psychophysical task. Background: Previous studies (Barenholtz and Feldman, VSS 2001) using a simple probe comparison task (i.e., classifying two spatially separated circular probes as "same" or "different" in size) have shown a systematic effect of contour curvature: responses are...
Article
Shape representation was studied using a change detection task. Observers viewed two individual shapes in succession, either identical or one a slightly altered version of the other, and reported whether they detected a change. We found a dramatic advantage for changes involving shape concavities compared to those involving convexities of equal mag...
Article
While the mapping from a distal stimulus to a retinal image is generally many-to-one, non-accidental properties in the image can point to a unique distal structure (Witkin and Tannenbaum, 1983) . The disproportionate degree of information carried by these properties suggests that the visual system might be particularly attuned to detecting and repr...
Conference Paper
In recent work, we showed that (1) the visual system systematically takes into account the curvature of an inducing contour when extrapolating its shape behind an occluder, and (2) extrapolation shape is characterized by a systematic decay in curvature with increasing distance from the point of occlusion (Singh & Fulvio, PNAS 2005). The current stu...
Article
Although orientation of line segments and simple shapes is a well-studied area of vision, little is known about the factors that influence perceived orientation of complex shapes. Study of these factors is of great interest because it allows for a better understanding of how local shape attributes are integrated into a global shape description. We...
Article
Research on 3D shape has focused largely on the perception of local geometric properties, such as surface depth, orientation, or curvature. Relatively little is known about how the visual system organizes local measurements into global shape representations. Here, we investigated how the perceptual organization of shape affects the perception of ph...