The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
John P. Spencer - One of the best experts on this subject based on the ideXlab platform.
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biased feedback in spatial recall yields a violation of delta rule learning
Psychonomic Bulletin & Review, 2010Co-Authors: John Lipinski, John P. Spencer, Larissa K SamuelsonAbstract:This study investigates whether inductive processes influencing spatial memory performance generalize to supervised learning scenarios with differential feedback. After providing a location memory response in a spatial recall task, participants received visual feedback showing the target location. In critical blocks, feedback was systematically biased either 4° toward the vertical axis (toward condition) or 4° farther away from the vertical axis (away condition). Results showed that the weaker teaching signal (i.e., a smaller difference between the remembered location and the feedback location) produced a stronger experience-dependent change over blocks in the away condition than in the toward condition. This violates delta rule learning. Subsequent simulations of the Dynamic Field theory of spatial cognition provide a theoretically unified account of these results.
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generalizing the Dynamic Field theory of spatial cognition across real and developmental time scales
Brain Research, 2008Co-Authors: Vanessa R. Simmering, Anne R Schutte, John P. SpencerAbstract:Within cognitive neuroscience, computational models are designed to provide insights into the organization of behavior while adhering to neural principles. These models should provide sufficient specificity to generate novel predictions while maintaining the generality needed to capture behavior across tasks and/or time scales. This paper presents one such model, the Dynamic Field theory (DFT) of spatial cognition, showing new simulations that provide a demonstration proof that the theory generalizes across developmental changes in performance in four tasks-the Piagetian A-not-B task, a sandbox version of the A-not-B task, a canonical spatial recall task, and a position discrimination task. Model simulations demonstrate that the DFT can accomplish both specificity-generating novel, testable predictions-and generality-spanning multiple tasks across development with a relatively simple developmental hypothesis. Critically, the DFT achieves generality across tasks and time scales with no modification to its basic structure and with a strong commitment to neural principles. The only change necessary to capture development in the model was an increase in the precision of the tuning of receptive Fields as well as an increase in the precision of local excitatory interactions among neurons in the model. These small quantitative changes were sufficient to move the model through a set of quantitative and qualitative behavioral changes that span the age range from 8 months to 6 years and into adulthood. We conclude by considering how the DFT is positioned in the literature, the challenges on the horizon for our framework, and how a Dynamic Field approach can yield new insights into development from a computational cognitive neuroscience perspective.
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planning discrete movements using a continuous system insights from a Dynamic Field theory of movement preparation
Motor Control, 2007Co-Authors: Anne R Schutte, John P. SpencerAbstract:The timed-initiation paradigm developed by Ghez and colleagues (1997) has revealed two modes of motor planning: continuous and discrete. Continuous responding occurs when targets are separated by less than 60° of spatial angle, and discrete responding occurs when targets are separated by greater than 60°. Although these two modes are thought to reflect the operation of separable strate gic planning systems, a new theory of movement preparation, the Dynamic Field Theory, suggests that two modes emerge flexibly from the same system. Experi ment 1 replicated continuous and discrete performance using a task modified to allow for a critical test of the single system view. In Experiment 2, participants were allowed to correct their movements following movement initiation (the standard task does not allow corrections). Results showed continuous planning performance at large and small target separations. These results are consistent with the proposal that the two modes reflect the time-dependent “preshaping” of a single planning system.
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testing the Dynamic Field theory working memory for locations becomes more spatially precise over development
Child Development, 2003Co-Authors: Anne R Schutte, John P. Spencer, Gregor SchonerAbstract:The Dynamic Field theory predicts that biases toward remembered locations depend on the separation between targets, and the spatial precision of interactions in working memory that become enhanced over development. This was tested by varying the separation between A and B locations in a sandbox. Children searched for an object 6 times at an A location, followed by 3 trials at a B location. Two- and 4-year-olds', but not 6-year-olds', responses were biased toward A when A and B were 9-in. and 6-in. apart. When A and B were separated by 2 in., however, 4- and 6-year-olds' responses were biased toward A. Thus, the separation at which responses were biased toward A decreased across age groups, supporting the predictions of the theory.
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Generalizing the Dynamic Field Theory of the A-not-B Error Beyond Infancy: Three-Year-Olds’ Delay- and Experience-Dependent Location Memory Biases
Child development, 2002Co-Authors: Anne R Schutte, John P. SpencerAbstract:Thelen and colleagues recently proposed a Dynamic Field theory (DFT) to capture the general processes that give rise to infants’ performance in the Piagetian A-not-B task. According to this theory, the same general processes should operate in noncanonical A-not-B-type tasks with children older than 12 months. Three predictions of the DFT were tested by examining 3-year-olds’ location memory errors in a task with a homogeneous task space. Children pointed to remembered locations after delays of 0 s to 10 s. The spatial layout of the possible targets and the frequency with which children moved to each target was varied. As predicted by the DFT, children’s responses showed a continuous spatial drift during delays toward a longer term memory of previously moved-to locations. Furthermore, these delay-dependent effects were reduced when children moved to an “A” location on successive trials, and were magnified on the first trial to a nearby “B” location. Thus, the DFT generalized to capture the performance of 3-year-old children in a new task. In contrast to predictions of the DFT, however, 3-year-olds’ responses were also biased toward the midline of the task space—an effect predicted by the category adjustment (CA) model. These data suggest that young children’s spatial memory responses are affected by delay- and experience-dependent processes as well as the geometric structure of the task space. Consequently, two current models of spatial memory—the DFT and the CA model—provide incomplete accounts of children’s location memory abilities.
Anne R Schutte - One of the best experts on this subject based on the ideXlab platform.
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test of a relationship between spatial working memory and perception of symmetry axes in children 3 to 6 years of age
Spatial Cognition and Computation, 2020Co-Authors: Yinbo Wu, Anne R SchutteAbstract:Children’s memory responses to a target location in a homogenous space change from being biased toward the midline of the space to being biased away. According to Dynamic Field Theory (DFT), improv...
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generalizing the Dynamic Field theory of spatial cognition across real and developmental time scales
Brain Research, 2008Co-Authors: Vanessa R. Simmering, Anne R Schutte, John P. SpencerAbstract:Within cognitive neuroscience, computational models are designed to provide insights into the organization of behavior while adhering to neural principles. These models should provide sufficient specificity to generate novel predictions while maintaining the generality needed to capture behavior across tasks and/or time scales. This paper presents one such model, the Dynamic Field theory (DFT) of spatial cognition, showing new simulations that provide a demonstration proof that the theory generalizes across developmental changes in performance in four tasks-the Piagetian A-not-B task, a sandbox version of the A-not-B task, a canonical spatial recall task, and a position discrimination task. Model simulations demonstrate that the DFT can accomplish both specificity-generating novel, testable predictions-and generality-spanning multiple tasks across development with a relatively simple developmental hypothesis. Critically, the DFT achieves generality across tasks and time scales with no modification to its basic structure and with a strong commitment to neural principles. The only change necessary to capture development in the model was an increase in the precision of the tuning of receptive Fields as well as an increase in the precision of local excitatory interactions among neurons in the model. These small quantitative changes were sufficient to move the model through a set of quantitative and qualitative behavioral changes that span the age range from 8 months to 6 years and into adulthood. We conclude by considering how the DFT is positioned in the literature, the challenges on the horizon for our framework, and how a Dynamic Field approach can yield new insights into development from a computational cognitive neuroscience perspective.
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planning discrete movements using a continuous system insights from a Dynamic Field theory of movement preparation
Motor Control, 2007Co-Authors: Anne R Schutte, John P. SpencerAbstract:The timed-initiation paradigm developed by Ghez and colleagues (1997) has revealed two modes of motor planning: continuous and discrete. Continuous responding occurs when targets are separated by less than 60° of spatial angle, and discrete responding occurs when targets are separated by greater than 60°. Although these two modes are thought to reflect the operation of separable strate gic planning systems, a new theory of movement preparation, the Dynamic Field Theory, suggests that two modes emerge flexibly from the same system. Experi ment 1 replicated continuous and discrete performance using a task modified to allow for a critical test of the single system view. In Experiment 2, participants were allowed to correct their movements following movement initiation (the standard task does not allow corrections). Results showed continuous planning performance at large and small target separations. These results are consistent with the proposal that the two modes reflect the time-dependent “preshaping” of a single planning system.
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testing the Dynamic Field theory working memory for locations becomes more spatially precise over development
Child Development, 2003Co-Authors: Anne R Schutte, John P. Spencer, Gregor SchonerAbstract:The Dynamic Field theory predicts that biases toward remembered locations depend on the separation between targets, and the spatial precision of interactions in working memory that become enhanced over development. This was tested by varying the separation between A and B locations in a sandbox. Children searched for an object 6 times at an A location, followed by 3 trials at a B location. Two- and 4-year-olds', but not 6-year-olds', responses were biased toward A when A and B were 9-in. and 6-in. apart. When A and B were separated by 2 in., however, 4- and 6-year-olds' responses were biased toward A. Thus, the separation at which responses were biased toward A decreased across age groups, supporting the predictions of the theory.
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Generalizing the Dynamic Field Theory of the A-not-B Error Beyond Infancy: Three-Year-Olds’ Delay- and Experience-Dependent Location Memory Biases
Child development, 2002Co-Authors: Anne R Schutte, John P. SpencerAbstract:Thelen and colleagues recently proposed a Dynamic Field theory (DFT) to capture the general processes that give rise to infants’ performance in the Piagetian A-not-B task. According to this theory, the same general processes should operate in noncanonical A-not-B-type tasks with children older than 12 months. Three predictions of the DFT were tested by examining 3-year-olds’ location memory errors in a task with a homogeneous task space. Children pointed to remembered locations after delays of 0 s to 10 s. The spatial layout of the possible targets and the frequency with which children moved to each target was varied. As predicted by the DFT, children’s responses showed a continuous spatial drift during delays toward a longer term memory of previously moved-to locations. Furthermore, these delay-dependent effects were reduced when children moved to an “A” location on successive trials, and were magnified on the first trial to a nearby “B” location. Thus, the DFT generalized to capture the performance of 3-year-old children in a new task. In contrast to predictions of the DFT, however, 3-year-olds’ responses were also biased toward the midline of the task space—an effect predicted by the category adjustment (CA) model. These data suggest that young children’s spatial memory responses are affected by delay- and experience-dependent processes as well as the geometric structure of the task space. Consequently, two current models of spatial memory—the DFT and the CA model—provide incomplete accounts of children’s location memory abilities.
Gregor Schoner - One of the best experts on this subject based on the ideXlab platform.
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using Dynamic Field theory to rethink infant habituation
Psychological Review, 2006Co-Authors: Gregor Schoner, Esther ThelenAbstract:: Much of what psychologists know about infant perception and cognition is based on habituation, but the process itself is still poorly understood. Here the authors offer a Dynamic Field model of infant visual habituation, which simulates the known features of habituation, including familiarity and novelty effects, stimulus intensity effects, and age and individual differences. The model is based on a general class of Dynamic (time-based) models that integrate environmental input in varying metric dimensions to reach a single decision. Here the authors provide simulated visual input of varying strengths, distances, and durations to 2 coupled and interacting Fields. The 1st represents the activation that drives "looking," and the 2nd, the inhibition that leads to "looking away," or habituation. By varying the parameters of the Field, the authors simulate the time course of habituation trials and show how these Dynamics can lead to different depths of habituation, which then determine how the system dishabituates. The authors use the model to simulate a set of influential experiments by R. Baillargeon (1986, 1987a, 1987b) using the well-known "drawbridge" paradigm. The Dynamic Field model provides a coherent explanation without invoking infant object knowledge. The authors show that small changes in model parameters can lead to qualitatively different outcomes. Because in typical infant cognition experiments, critical parameters are unknown, effects attributed to conceptual knowledge may be explained by the Dynamics of habituation.
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testing the Dynamic Field theory working memory for locations becomes more spatially precise over development
Child Development, 2003Co-Authors: Anne R Schutte, John P. Spencer, Gregor SchonerAbstract:The Dynamic Field theory predicts that biases toward remembered locations depend on the separation between targets, and the spatial precision of interactions in working memory that become enhanced over development. This was tested by varying the separation between A and B locations in a sandbox. Children searched for an object 6 times at an A location, followed by 3 trials at a B location. Two- and 4-year-olds', but not 6-year-olds', responses were biased toward A when A and B were 9-in. and 6-in. apart. When A and B were separated by 2 in., however, 4- and 6-year-olds' responses were biased toward A. Thus, the separation at which responses were biased toward A decreased across age groups, supporting the predictions of the theory.
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Dynamic Field theory of movement preparation
Psychological Review, 2002Co-Authors: Wolfram Erlhagen, Gregor SchonerAbstract:A theoretical framework for understanding movement preparation is proposed. Movement parameters are represented by activation Fields, distributions of activation defined over metric spaces. The Fields evolve under the influence of various sources of localized input, representing information about upcoming movements. Localized patterns of activation self-stabilize through cooperative and competitive interactions within the Fields. The task environment is represented by a 2nd class of Fields, which preshape the movement parameter representation. The model accounts for a sizable body of empirical findings on movement initiation (continuous and graded nature of movement preparation, dependence on the metrics of the task, stimulus uncertainty effect, stimulus-response compatibility effects, Simon effect, precuing paradigm, and others) and suggests new ways of exploring the structure of motor representations.
Yong Lai Zhang - One of the best experts on this subject based on the ideXlab platform.
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recent developments in superhydrophobic surfaces with unique structural and functional properties
Soft Matter, 2012Co-Authors: Yong Lai ZhangAbstract:The surface wettability control of solid materials has been considered as an essential aspect of surface chemistry. In the past decade, superhydrophobic surfaces have revealed a cornucopia of novel structural and functional properties, exhibiting considerable importance in both fundamental research and practical applications. In this review, we summarize the recent developments of superhydrophobic surfaces with unique structural and functional properties. Both the fabricative methods and the working performance of superhydrophobic surfaces with multidisciplinary functionalities including self-cleaning, icephobicity, anti-corrosion, drag reduction, transparency, anti-reflection, structural color, droplet transportation, anisotropy, oil–water separation, water supporting force, superamphiphobicity and responsive switching, have been discussed briefly. Finally, the current challenges and future prospects of this Dynamic Field are discussed based on our own opinion.
Sami F Masri - One of the best experts on this subject based on the ideXlab platform.
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system identification of alfred zampa memorial bridge using Dynamic Field test data
Journal of Structural Engineering-asce, 2009Co-Authors: Babak Moaveni, Joel P Conte, Ahmed Elgamal, Sami F MasriAbstract:The Alfred Zampa Memorial Bridge (AZMB), a newly built long-span suspension bridge, is located 32km northeast of San Francisco on interstate Highway I-80. A set of Dynamic Field tests were conducted on the AZMB in November 2003, just before the bridge opening to traffic. These tests provided a unique opportunity to identify the modal properties of the bridge in its as-built condition with no previous traffic loads or seismic excitation. A benchmark study on modal identification of the AZMB is performed using three different state-of-the-art system identification algorithms based on ambient as well as forced vibration measurements. These system identification methods consist of: (1) the multiple-reference natural excitation technique combined with the eigensystem realization algorithm, (2) the data-driven stochastic subspace identification method, and (3) the enhanced frequency domain decomposition method. Overall, the modal parameters identified using these system identification methods are found to be in very good agreement for each type of tests (ambient and forced vibration tests). For most vibration modes, the natural frequencies and mode shapes identified using the two different types of test data also match very well. However, the modal damping ratios identified from forced vibration test data are in general higher than those estimated from ambient vibration data. The identified natural frequencies and mode shapes are finally compared with their analytical counterparts from a three-dimensional finite element model of the AZMB. The modal properties of the AZMB presented in this paper can be used as baseline in future health monitoring studies of this bridge.
