Use Of Such Representations Research Articles

Visual adaptation selective for individual limbs reveals hierarchical human body representation.

The spatial relationships between body parts are a rich source of information for person perception, with even simple pairs of parts providing highly valuable information. Computation of these relationships would benefit from a hierarchical representation, where body parts are represented individually. We hypothesized that the human visual system makes use of such representations. To test this hypothesis, we used adaptation to determine whether observers were sensitive to changes in the length of one body part relative to another. Observers viewed forearm/upper arm pairs where the forearm had been either lengthened or shortened, judging the perceived length of the forearm. Observers then adapted to a variety of different stimuli (e.g., arms, objects, etc.) in different orientations and visual field locations. We found that following adaptation to distorted limbs, but not non-limb objects, observers experienced a shift in perceived forearm length. Furthermore, this effect partially transferred across different orientations and visual field locations. Taken together, these results suggest the effect arises in high level mechanisms specialized for specific body parts, providing evidence for a representation of bodies based on parts and their relationships.

Throwing one’s voice and speaking for others: Performative vocality and transcription in the Assemblées of the long nineteenth century

This article examines the role of the voice in practices of representation in nineteenth-century parliament. It asks how textual representations of vocal practices of political representation can be mobilized for the histories of politics and representation, and how such an enquiry can complicate our understanding of representation as a multifarious practice organized around speech. The article takes a particular case as its point of departure: that of the different Assemblées of nineteenth-century France, its vocal performances and the many practices of transcription, reporting and comment, such as those produced by an increasingly professional class of stenographers, journalists and satirists. Tracing the various ways in which representatives ventriloquized others, and were ventriloquized by different audiences and commentators, it draws attention to the acoustic aspects of parliamentary speech, and of the concept of representation itself. We focus on the representative quality of political vocality itself and also consider the practice of representing political speeches on paper (e.g. as transcripts or by journalists). Finally, and most importantly, we reflect on how the use of such representations could make the MP’s voice present even where his body was not. Thinking about the French case in a wide transnational context, we argue that including extra-linguistic aspects of speech in our analyses of oratory might draw attention to the embodied practices that served to make, imagine or sometimes disrupt beliefs about national belonging – thus delving into understandings of trustworthiness and political effectiveness beyond the particular national framework. Consequently, thinking about speech with and as sound allows us to think beyond the nation or national institutions when examining the practice of modern politics, its development and the continued importance of ventriloquial imaginations and materialities in political speech.

The Comparative Psychology of Intelligence: Some Thirty Years Later.

After re-reading Macphail’s (1987) essay “The Comparative Psychology of Intelligence” with all the associated commentaries, I was struck by how contemporary many of the arguments and counter-arguments still appear. Of course, we now know much more about the abilities of many more species (including their neurobiology) and fewer researchers currently favor explanations of behavior based solely on associative processes; however, the role of contextual variables in comparative psychology still remains cloudy. I discuss these issues briefly. Given my research interests involving the cognitive and communicative abilities of Grey parrots, the one aspect of the original article upon which I feel I can comment in depth involves Macphail’s claims about the importance of language—and specifically syntax—in problem-solving and thus in placing humans above all other creatures. Granted, no other species has (or in my opinion is likely ever to acquire) everything that goes into what is considered “human language.” Nevertheless, several other species have acquired symbolic representation, and considerable information now exists upon which to base an argument that such acquisition by itself enables more complex and “human-like” cognitive processes. Such processes may form the basis of the kind of intelligence that is measured—not surprisingly—with human-based tasks, including the use of such representations as a means to directly query non-human subjects in ways not unlike those used with young children.

Third‐grade teachers’ self‐reported use of multiplication and division models

AbstractVisual representations and manipulatives are a highly advocated mathematical tool for the teaching and learning of multiplication and division. Although there is some prior research on elementary teachers’ general use of manipulatives and visual representations, there is little to no specific focus on use of such representations on a specific mathematical concept. The present study examined third grade teachers’ reported use of visual representations for teaching multiplication and division. Findings indicate prevalent use of discrete models and infrequent use of continuous models. Length models and number lines are rarely used across all Common Core standards focusing on multiplication/division, with numeric‐only representations being reported frequently across all standards. Groups‐of and array models were the most prevalent visual model reported by third grade teachers. Although teachers report higher degrees of access to certain materials than previous reports on manipulative use, interview data suggests this may have more to do with purchase agreements between school districts and textbook companies than pedagogical preferences of classroom teachers. Supporting findings in prior decades, teachers in the present study report prevalent use of flashcards, charts and grid paper, and variations of counters.

Enhanced conceptual understanding in first year mechanics through modelling

As part of the National HE STEM programme, we have developed and implemented a modelling curriculum in first year mechanics to overcome well known conceptual difficulties. By modelling, we mean more than just the development of mathematical equations to describe the evolution of a physical system; we also mean the use of multiple representations both to understand the problem at hand as well as to develop a solution. We have developed a structured approach to both teaching and assessing the use of such representations through the ACME protocol: Assess the problem, Conceptualise the Model, and Evaluate the solution. This paper describes the implementation of this protocol within a conventional lecture setting during a single semester of the 2011-12 academic session and demonstrates the impact on conceptual understanding of 42 students though pre-course and post-course testing using the Force Concept Inventory (FCI). Detailed analysis shows that on virtually every question in the FCI student performance improved, with questions 4 and 15, relating to Newton’s third law, showing especially large gains. The average FCI score rose from 17.7 (out of 30) to 22.5, with the distribution of post-instruction scores being statistically significantly different (p=0.0001) from the distribution of pre-instruction scores.

Young children’s agent-neutral representations of action roles

Recent developmental research has shown that young children coordinate complementary action roles with others. But what do they understand about the logical structure of such roles? Do they have an agent-neutral conception of complementary action roles, grasping that such roles can be variably filled by any two agents or even by one agent over time? Accordingly, can they make use of such representations for planning both their own and others’ actions? To address these questions, 3- and 4-year-olds were introduced to an activity comprising two action roles, A and B, by seeing either two agents performing A and B collaboratively or one agent performing A and B individually. Children’s flexible inferences from these demonstrations were then tested by asking them later on to plan ahead for the fulfillment of one of the roles either by themselves or by someone else. The 4-year-olds competently drew inferences in all directions, from past individual and collaborative demonstrations, when planning how they or someone else would need to fulfill the roles in the future. The 3-year-olds, in contrast, showed more restricted competence; they were capable of such inferences only when planning in the immediate present. Taken together, these results suggest that children form and use agent-neutral representations of action roles by 3years of age and flexibly use such representations for episodic memory and future deliberation in planning their own and others’ actions by 4years of age. The findings are discussed in the broader context of the development of understanding self–other equivalence and agent-neutral frames of references.

Assessment in the One-Shot Session: Using Pre- and Post-tests to Measure Innovative Instructional Strategies among First-Year Students

Many studies focus on the use of different assessment tools within information literacy instruction; however, there are very few that discuss how pre- and post-tests can be used to gauge student learning, and even fewer of those published deal with pre- and post-test assessment within the one-shot paradigm. This study explores the effectiveness of using nonlinguistic representations—kinesthetic, graphic, and physical models—in one-shot library sessions for first-year students in SLU 100 Introduction to the University Experience. As hypothesized, the findings suggest that the use of such representations can enhance student learning and assist in developing research skills that are essential to acquiring information literacy.

Turning Experiments into Objects: The Cognitive Processes Involved in the Design of a Lab‐on‐a‐Chip Device

AbstractBackgroundIncreasingly, modern engineers are designing miniature devices that integrate complex activities, actions, processes, or operations involving many steps, persons, and equipment; a good example is a microfluidic lab‐on‐a‐chip device. The design of such devices is cognitively demanding and requires the generation of multiple model representations, which are used in an iterative fashion to analyze and improve prototype designs.PurposeThis study addresses two questions: How are various representations and prototypes used in the iterative design and building of a microfluidic lab‐on‐a‐chip device in a systems biology laboratory? In this design process, what cognitive functions did the representations serve?Design/MethodThis case study employed mixed methods. We utilized the standard ethnographic methods of participant observation, open‐ended interviewing of participants, and artifact collection in an integrated systems biology research lab. Data were analyzed using open and axial coding. We also used cognitive‐historical analysis to collect and analyze data from traditional historical sources (publications, grant proposals, laboratory notebooks, and technological artifacts) to recover how the salient representational, methodological, and reasoning practices were developed and used by the researchers.ResultsThe device design involved complex interactions among mental models, computational models, and building and testing prototypes; tagging and visualizations were used to query and validate the prototypes as well as the computational models; all these were integrated to meet stringent experimental and fabrication constraints. Integration takes place across many different kinds of representations. The building of external representations helped not just to off‐load cognitive load but also to add detail and constraints to the mental model.ConclusionsRepresentational fluency and flexibility are required to manage the complexity of modern bioengineered devices. To support the development of such fluency and flexibility, engineering students must understand the function and the use of such representations, an instructional goal that has implication for new models of learning.

What can cognitive architectures do for robotics?

Abstract Research in robotic systems has traditionally been identified with approaches that are characterized by the use of carefully crafted representations and processes to find optimal solutions. The use of such representations and processes, which we refer to as the algorithmic approach, is uniquely suited for problems requiring strong models, i.e., tasks and domains that are well defined, and/or involve close interaction with the environment. These problems have historically been the focus of robotics research because they exercise perceptual, motor and manipulation capabilities that form the basic foundational abilities required for every robotic agent. Recent work (for example ROS and Tekkotsu) on the abstraction and encapsulation of perception and motor functionality has standardized the above mentioned foundational abilities and allowed researchers to study problems in less clearly defined and open-ended domains: problems that have previously been considered the province of AI and Cognitive Science. In this paper, we argue that the study of these problems (examples of which include multi-agent interaction, instruction following and reasoning in complex domains) referred to under the rubric of Cognitive Robotics is best achieved via the use of cognitive architectures – unified computational frameworks developed specifically for general problem solving and human cognitive modeling. We lay out the relevant architectural concepts and principles and illustrate them using nine cognitive architectures that are under active development – Soar, ACT-R, CLARION, GMU-BICA, Polyscheme, Co-JACK, ADAPT, ACT-R/E, and SS-RICS.

Design strategies for direct multi-scale and multi-orientation feature extraction in the log-polar domain

Despite the well known advantages that a space-variant representation of the visual signal offers, the required adaptation of the algorithms developed in the Cartesian domain, before applying them in the log-polar space, has limited a wide use of such representation in visual processing applications. In this paper, we present a set of original rules for designing a discrete log-polar mapping that allows a direct application in the log-polar domain of the algorithms, based on spatial multi-scale and multi-orientation filtering, originally developed for the Cartesian domain. The advantage of the approach is to gain, without modifications, an effective space-variance and data reduction. Such design strategies are based on a quantitative analysis of the relationships between the spatial filtering and the space-variant representation. We assess the devised rules by using a distributed approach based on a bank of band-pass filters to compute reliable disparity maps, by providing quantitative measures of the computational load and of the accuracy of the computed visual features.

Spatial and temporal knowledge representation

Knowledge Representation (KR) originated as a discipline within Artificial Intelligence, and is concerned with the representation of knowledge in symbolic form so that it can be stored and manipulated on a computer. This article surveys that part of KR that is concerned with the representation of space and time, with particular reference to the use of such representations in geographical information science.

Models of musical timbre using cortical spectro-temporal receptive fields and temporal codes

It has been customary to propose several ‘‘descriptive’’ definitions to quantify timbre as one of the basic attributes of sound. Multidimensional scaling techniques have proposed several acoustic dimensions to characterize the timbre of subsets of sounds. Yet, in the general case, timbre is an intricate percept difficult to relate to concise acoustic cues. Timbre probably reflects the dynamic interactions between spectral and temporal characteristics of sound that play a crucial role in identifying natural sources and convey a wealth of information about the environment. Recent physiological investigations revealed possible neural mechanisms to extract and represent the spectral and temporal information in complex sounds. At the level of the primary auditory cortex, spectro-temporal receptive fields exhibit a multiscale representation that captures many aspects of dynamic sound spectra. In the current study, we explore the potential correspondence between these cortical properties and the identification of musical instruments. We investigate the use of such representation as a quantitative descriptor of musical timbre, as validated by behavioral data from human subjects. Additionally, we examine biologically plausible coding strategies in this multidimensional cortical mapping involving spike-timing information.

On spectral flow symmetry and Knizhnik–Zamolodchikov equation

It is well known that five-point function in Liouville field theory provides a representation of solutions of the SL(2,R)k Knizhnik–Zamolodchikov equation at the level of four-point function. Here, we make use of such representation to study some aspects of the spectral flow symmetry of slˆ(2)k affine algebra and its action on the observables of the WZNW theory. To illustrate the usefulness of this method we rederive the three-point function that violates the winding number in SL(2,R) in a very succinct way. In addition, we prove several identities holding between exact solutions of the Knizhnik–Zamolodchikov equation.

A NEW REPRESENTATION FOR QUARTIC CURVES AND COMPLETE SETS OF GEOMETRIC INVARIANTS

Many free-form object boundaries can be modeled by quartics with bounded zero sets. The fact that any nondegenerate closed-bounded algebraic curve of even degree n=2p can be expressed as the product of p conics, which are real ellipses, plus a remaining polynomial of degree n-2,12 can be utilized to express a nondegenerate quartic as the product of two leading ellipses plus a third conic which might be either a closed curve (an ellipse) or an open curve (a hyperbola). However, it can be shown that the leading ellipses can be modified with appropriate constants by constraining the third conic to be a circle, thus implying a 2-ellipse and 1-circle; i.e. an elliptical-circular(E2C)representation of the quartic. The use of such representations is to simplify the analysis of quartics by exploiting the well-known properties of conics and to develop a set of functionally independent geometric invariants for recognition purposes. Also, it is shown that the underlying Euclidean transformation between two configurations of the same quartic can be determined using the centers of the three conics.

Fast Procedure to Obstacle Representation in the Configuration Space for Mobile Robots

In order to create an autonomous mobile robot it is necessary to develop powerful methods for path planning, avoiding collisions with low computational costs. In this paper, a mathematical formalism for the general evaluation of the representation in the configuration space of any set of obstacles is presented. The use of such representation reduces drastically the complexity of the problem. As it is shown in the paper, with the proposed method, the obstacle representation can be seen as a convolution of two functions that describe the robot and the obstacles respectively. Additionally, the computational load is independent of the shape and number of obstacles and of the robot shape. In the final implementation the Fast Fourier Transform is used to take advantage of the intrinsic parallelable nature of this tool. The resulting algorithm can also be very easily implemented in a parallel way. All the considerations above allow to reduce drastically the computational time making the algorithm suitable for real applications. The method has been applied to robots moving on a plane in a 2D and a 3D dimensional workspace

Efficient algorithm for quantitative assessment of similarities among atoms in molecules.

A new algorithm for quantitative assessment of similarity between two atoms in molecules is presented. Both the atomic similarity index and its derivatives with respect to the three Euler angles that describe the mutual orientation of the atoms under comparison are computed efficiently by taking advantage of the recently developed analytical representations for atomic zero-flux surfaces. The use of such representations makes it possible to substantially enhance the accuracy of the computed similarity indices without increasing the cost of their evaluation. Numerical tests involving oxygen atoms in several carbonyl compounds demonstrate the ability of the new algorithm to discern small changes in atomic similarity that are brought about by second-neighbor effects. Comparisons among hydrogen atoms in the acrolein molecule reveal the usefulness of the similarity index in detection and quantification of the effects of steric interactions on atomic shapes. © 1996 by John Wiley & Sons, Inc.

Time‐frequency representation of scattering from a target in a bounded medium

Time‐frequency representations applied to target scattering enable one to observe target characteristics that are of particular interest in inverse scattering problems. In this work such representations are extended to targets placed in a shallow water environment where target characteristics as well as shallow water characteristics appear in the time‐frequency domain. The Gabor transformation is applied to scattering from an elastic shell placed in a bounded medium to display the combination of the waveguide effects (shallow water propagation) and the target effects (elastic wave propagation). The use of such representations for classification purposes is discussed.

P-adic Heisenberg group and Maslov index

A “system of coordinates” on a set Λ of selfdual lattices in a two-dimensionalp-adic symplectic space (V,ℬ) is suggested. A unitary irreducible representation of the Heisenberg group of the space (V,ℬ) depending on a lattice ℒ∈Λ (an analogue of the Cartier representation) is constructed and its properties are investigated. By the use of such representations for three different lattices ℒ∈Λ one defines the Maslov index μ=μ(ℒ1,ℒ2,ℒ3) of a triple of lattices. Properties of the index μ are investigated and values of μ in coordinates for different triples of lattices are calculated.

Uncertainty and inference in the visual system

Recent physiological research has indicated that the visual system makes use of units responsive to Gabor signals in the analysis of visual stimuli. Such functions effect a tradeoff between pure spatial- and frequency-domain descriptions. The authors explain the use of such representations in vision, considered as a process in inference from the retinal signals to a symbolic description. The appropriate mathematical structure for the inference is that of the subspaces of the signal vector space, a feature which it shares with quantum mechanics. The theory is derived directly from the fundamental constraints on visual inference. It is then shown to be consistent with many of the known properties of the visual system. In particular, a major feature of the inference system-the occurrence of interference effects-has already been observed in visual system operation.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Discrete representation of signals

In processing continuous-time signals by digitalmeans, it is necessary to represent the signal by a digital sequence. There are many ways other than periodic sampling for obtaining such a sequence. The requirements for such representations and some examples are discussed within the framework of simulating linear time-invariant systems. The representation of digital sequences by other digital sequences is also discussed, with particular emphasis on the use of such representations to implement a nonlinear warping of the digital frequency axis. Some applications and hardware implementation of this digital-frequency warping are described.