Browsing by Author "Pomerantz, James R."
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Item A century of Gestalt psychology in visual perception: II. Conceptual and theoretical foundations(American Psychological Association, 2012) Wagemans, Johan; Feldman, Jacob; Gepshtein, Sergei; Kimchi, Ruth; Pomerantz, James R.; van der Helm, Peter A.; van Leeuwen, CeesOur first review article (Wagemans et al., 2012) on the occasion of the centennial anniversary of Gestalt psychology focused on perceptual grouping and figure-ground organization. It concluded that further progress requires a reconsideration of the conceptual and theoretical foundations of the Gestalt approach, which is provided here. In particular, we review contemporary formulations of holism within an information-processing framework, allowing for operational definitions (e.g., integral dimensions, emergent features, configural superiority, global precedence, primacy of holistic/configural properties) and a refined understanding of its psychological implications (e.g., at the level of attention, perception, and decision). We also review 4 lines of theoretical progress regarding the law of Prägnanz-the brain's tendency of being attracted towards states corresponding to the simplest possible organization, given the available stimulation. The first considers the brain as a complex adaptive system and explains how self-organization solves the conundrum of trading between robustness and flexibility of perceptual states. The second specifies the economy principle in terms of optimization of neural resources, showing that elementary sensors working independently to minimize uncertainty can respond optimally at the system level. The third considers how Gestalt percepts (e.g., groups, objects) are optimal given the available stimulation, with optimality specified in Bayesian terms. Fourth, structural information theory explains how a Gestaltist visual system that focuses on internal coding efficiency yields external veridicality as a side effect. To answer the fundamental question of why things look as they do, a further synthesis of these complementary perspectives is required.Item False Pop Out(2015-06-22) Orsten, Kimberley D.; Pomerantz, James R.; Dannemiller, James L; Lane, David M; Grandy, Richard EA single, unique target often pops out quickly and efficiently from a field of homogenous distractors in visual search. Pop out has helped shape theories of visual attention and feature integration as well as to identify basic features in human vision. The present experiments demonstrate a new phenomenon, false pop out, wherein one of the homogenous distractors competes with the singleton target to pop out, perhaps by breaking an overall grouping or pattern emerging from the display. Using a compilation of several studies, this research reports the effect in a number of display contexts using a number of different stimuli, and provides converging evidence toward the idea that low and high level features contribute equally to the primary perceptual experience, a counterintuitive finding for most current theories of visual search.Item Grouping and search efficiency in emergent features and topological properties in human vision(2010) Portillo, Mary C.; Pomerantz, James R.A series of three experiments were designed to test for Emergent Features, which, in Gestalt psychology, are indicative of grouping. By using basic elements such as dots or lines and building EFs sequentially, while maintaining the original discrimination constant, it was possible to compare the strength of different EFs. Proximity, Orientation, Symmetry, Linearity, Surroundedness, Inside/Outside relationship, Collinearity, Parallelism, Inflection Point and Closure were tested. A Configural Superiority Effect (CSE, where the RT in a composite condition is shorter than the RT in a singleton condition) was diagnostic of the presence of an EF in an Odd Quadrant task. Proximity, Orientation, Linearity, inside/Outside and Collinearity produced CSEs and thus behave as basic in human vision. Mixed results were obtained for Symmetry and Parallelism. Further, Inflection Point and Closure were only suggested in the stimuli, so they cannot be ruled out as EFs.Item Human Olfactory Perception: Characteristics, Mechanisms and Functions(2013-09-16) Chen, Jennifer; Pomerantz, James R.; Chen, Denise; Logan, Jessica M.Olfactory sensing is ubiquitous across animals and important for survival. Yet, its characteristics, mechanisms, and functions in humans remain not well understood. In this dissertation, I present four studies on human olfactory perception. Study I investigates the impact of short-term exposures to an odorant on long-term olfactory learning and habituation, while Study II examines human ability to localize smells; Study III probes visual-olfactory integration of object representations, and Study IV explores the role of olfaction in sensing nutrients. Several conclusions are drawn from these studies. First, brief intermittent exposures to even a barely detectable odorant lead to long-term incremental odorant-specific habituation. Second, humans localize smells based on gradient cues between the nostrils. Third, there is a within-hemispheric advantage in the integration of visual-olfactory object representations. Fourth, olfaction partakes in nutrient-sensing and facilitates the detection of food. Some broader implications of our findings are discussed.Item Modeling Curved Movement(2013-09-16) Gallagher, Melissa; Byrne, Michael D.; Kortum, Philip; Pomerantz, James R.This work aims to further the understanding of the trajectory and velocity profile of curved motion. Two competing theories, the two-thirds power law and the minimum jerk velocity profile, were tested. A set of two experiments was run that had the subjects generate curved motion. The first experiment had subjects move along a bounded oval and the second experiment had subjects move is a less constrained manner inducing a curved path. The study shows evidence for the expected effects of distance travel and allowable room for error. The evidence for the two movement profiles explaining the data is minimal.Item Neural Signatures of the Configural Superiority Effect and Fundamental Emergent Features in Human Vision(Springer Nature, 2018) Costa, Thiago Leiros; Orsten-Hooge, Kimberley; Rêgo, Gabriel Gaudêncio; Wagemans, Johan; Pomerantz, James R.; Boggio, Paulo SérgioThe concepts of grouping, emergence, and superadditivity (when a whole is qualitatively different from the sum of its parts) are critical in Gestalt psychology and essential to properly understand the information processing mechanisms underlying visual perception. However, very little is known about the neural processes behind these phenomena (particularly in terms of their generality vs. specificity and their time-course). Here, we used the configural superiority effect as a way to define "emergence" and "emergent features" operationally, employing an approach that can isolate different emergent features and compare them on a common scale. By assessing well-established event related potentials in a HD-EEG system, we found that the critical processes behind configural superiority and superadditive Gestalt phenomena are present in the window between 100 and 200 ms after stimulus onset and that these effects seem to be driven by specific attentional selection mechanisms. Also, some emergent features seem to be differentially processed in different brain hemispheres. These results shed new light on the issues of the generality vs. specificity of the neural correlates of different Gestalt principles, the hemispheric asymmetries in the processing of hierarchical image structure and the role of the N1 ERP component in reflecting feature selective mechanisms.Item Perceptual Organization in Vision: Emergent Features in Two-Line Space(2011) Stupina, Anna I.; Pomerantz, James R.What exactly are the "parts" that make up the whole object, and how and when do they group? The answer that is proposed hinges on Emergent Features: features that materialize from the configuration which make the object more discriminable from other objects. EFs are not possessed by any individual part and are processed as or more quickly than are the properties of the parts. The present experiments focus on visual discrimination of two-line configurations in an odd-quadrant task. RT data were obtained and compared with a prediction based on the number of EF differences in the odd quadrant (the higher the number of EF differences, the faster the discrimination was predicted). The results suggest that the EFs most responsible for the variations in RT might be lateral endpoint offset, intersections, parallelism, connectivity, number of terminators, and pixel count. Future directions include investigating the individual contributions and salience of EFs.Item Perceptual organization of random dot patterns: Area salient and memorable, proximity salient but forgotten(2004) Jewell, Stephen W.; Pomerantz, James R.I report four experiments designed to investigate the perceptual grouping processes by better understanding how a simple pattern of dots comes to be represented in the visual memory systems. Subjects were briefly shown a random set of point-like dots which were then masked, and subsequently reappeared with a possible added or deleted dot. Subjects detected deletions more accurately than additions and detected changes to the most peripheral dots more reliably than changes to interior dots, even those much closer to fixation. The most peripheral points appear to be objectized in a process that might be analogized as shrink wrapping. The circumscribed area is memorable and easily recalled despite brief presentations. The data are consistent with the view that the fastest of the perceptual processes is a global system which proceeds from the periphery inward toward fixation and that a separate slower local analytical sequence starts at fixation and works outward. I conjecture that proximity, one, if not the most salient of all features in the early perceptual processes that extract data from the sensory store and encode it in the visual memory systems, is not itself stored as part of the representation.Item Relative Salience of Emergent Features in Vision(2013-11-26) Cragin, Anna; Pomerantz, James R.; Byrne, Michael D.; O'Callaghan, Casey; Dannemiller, James L.What exactly are the ``parts'' that make up a whole object, and how and when do they group? The answer that is proposed hinges on Emergent Features: features that materialize from the configuration and that make the object more discriminable from other objects. EFs are not possessed by any individual part and are processed as or more quickly than are the properties of the parts. The present experiment focuses on visual discrimination of two-line configurations in an odd-quadrant task. Stimuli were created so as to isolate each EF in order to measure its contribution to speed of discrimination. Previous results suggest that the EFs most responsible for the variations in RT might be Lateral Endpoint Offset, Intersections, Parallelism, Connectivity, Terminator Count, Pixel Count, Closure, and Inside /Outside Relationship. The present study determined the boost or detriments in performance due to each EF and ranked them in terms of their relative salience. The most salient features were: Connectivity, Parallelism, Closure, Intersections, and Inside/Outside Relationship.Item The search for emergent features in vision: Looking at configural superiority effects with the odd-quadrant task(2006) Portillo, Mary C.; Pomerantz, James R.A series of three experiments were designed to test for Emergent Features, which, in Gestalt psychology, are indicative of grouping. By using basic elements such as dots or lines and building EFs sequentially, while maintaining the original discrimination constant, it was possible to compare the strength of different EFs. Proximity, Orientation, Symmetry, Linearity, Surroundedness, Inside/Outside relationship, Collinearity, Parallelism, Inflection Point and Closure were tested. A Configural Superiority Effect (CSE, where the RT in a composite condition is shorter than the RT in a singleton condition) was diagnostic of the presence of an EF in an Odd Quadrant task. Proximity, Orientation, Linearity, Inside/Outside and Collinearity produced CSEs and thus behave as basic in human vision. Mixed results were obtained for Symmetry and Parallelism. Further, Inflection Point and Closure were only suggested in the stimuli, so they cannot be ruled out as EFs.Item Visual perception of shape and area in random dot patterns(2007) Jewell, Stephen W.; Pomerantz, James R.I report five experiments in an exploratory study to investigate the perceptual grouping processes by better understanding how a simple pattern of dots comes to be represented in visual memory. Subjects were briefly shown a random set of point-like dots which were then masked and subsequently reappeared with a possible added or deleted dot. Subjects detected changes to peripheral dots more reliably than changes to interior dots, even those much closer to fixation. The most peripheral points appear to be objectized in a process that might be analogized as shrink wrapping. The circumscribed shape was memorable and easily recalled despite brief presentations. These data suggest a preattentive perceptual process beginning in the periphery and proceeding inward toward fixation as the visual system records the shape of the pattern.