Exploration styles modulate length perception through dynamic touch

Una de las habilidades más sorprendentes del sistema háptico es su capacidad de realizar estimaciones de algunas propiedades de los objetos, como el peso o el tamaño, utilizando invariantes de la mecánica rotacional que son accesibles por medio del subsistema propioceptivo; este campo de investigación se denomina tacto dinámico. En un ejemplo clásico de este paradigma experimental, el participante sujeta una varilla en su mano, sin estar ésta a la vista, y trata de igualar el tamaño percibido usando otra varilla que puede ver pero no blandir. En este experimento analizamos el papel del comportamiento exploratorio en esta situación, restringiendo el balanceo de la varilla en seis condiciones que varían la frecuencia y amplitud de los movimientos. Los resultados muestran que con una mayor velocidad en los movimientos se incrementa el ajuste de las estimaciones hápticas. Por ello, se argumenta que el momento de inercia es el mejor candidato informacional al realizar la tarea, ya que es una propiedad invariante que emerge únicamente cuando se aplica fuerza y se realizan movimientos rotacionales con el objeto. Se descartan otros candidatos informacionales, como el momento estático, o la masa, dado que no dependen de movimientos diferencialesExploration styles modulate length perception through dynamic touch. One of the most surprising capacities of the haptic system is the ability to estimate different properties of objects, like weight or length, through invariants of rotational mechanics that are accessible via the proprioceptive system. This field of research is called Dynamic Touch. In its classical experimental paradigm, the participant firmly grasps a rod that can be wielded but not seen, and he or she tries to match the hand-held rod’s length using another rod that can be seen but not wielded. In the experiment reported here, we focus on the role of the exploratory behavior, restricting the wielding in six conditions that vary both the amplitude and the frequency of movements. Increments in the speed of the movement are shown to increase the accuracy in the haptic estimation. It is argued that these results support the moment of inertia as the best informational candidate, given that it is an invariant property that only emerges when rotational torques are applied. Alternative candidates such as static moment or mass are discarded because they do not depend on differential movementsEste trabajo ha sido financiado por el proyecto FFI2009-13416-C02-02 del Ministerio de Ciencia e Innovación de Españ

Resonant Drivings in Global AdS

We revisit the case of a real scalar field in global AdS$_4$ subject to a periodic driving. We address the issue of adiabatic preparation and deformation of a time-periodic solution dual to a Floquet condensate. Then we carefully study the case of driving close to the normal mode resonant frequencies. We examine different slow protocols that adiabatically change the amplitude and/or the frequency of the driving. Traversing a normal mode frequency has very different results depending upon the sense of the frequency modulation. Generally, in the growing sense, the geometry reaches a periodically-modulated state, whereas in the opposite one, it collapses into a black hole. We study the suppression points. These are periodic solutions that are dual to a scalar field with vanishing $v.e.v., \langle \phi\rangle = 0$, instead of vanishing source. We also investigate quasi-periodic solutions that are prepared by driving with a combination of two normal resonant frequencies. We observe that, while the driving is on, the non-linear cascading towards higher frequencies is strongly suppressed. However, once the driving is switched off, the cascading takes over again, and in some cases, it eventually brings the solution to a collapse. Finally, we study the driving by a non-coherent thermal ensemble of resonant drivings that model stochastic noise. Our numerical results suggest the existence of stable regular solutions at sufficiently low temperature and a transition to collapse above some threshold.Comment: 27 pages + 1 appendix, 18 figure

El enfoque neogibsoniano como marco conceptual y metodológico para el diseño de programas de entrenamiento deportivo

The neogibsonian approach holds that the processes of perceptual and perceptual-motor learning consist of improving the detection and use of the abundant information that exists in task environments. This claim is the starting point for a conceptual and methodological framework used for the analysis of learning. The conceptual framework includes the concepts of the education of attention and calibration and, more recently, the ones of potential-based and direct learning. The present article introduces the neogibsonian approach and describes the implications of that approach for the design of training programs. In particular, the article addresses an explanation for the beneficial effects of variability in practice methods, and it considers the way in which variability should be introduced so as to achieve the beneficial effects

The history and philosophy of ecological psychology

Ecological Psychology is an embodied, situated, and non-representational approach pioneered by J. J. Gibson and E. J. Gibson. This theory aims to offer a third way beyond cognitivism and behaviorism for understanding cognition. The theory started with the rejection of the premise of the poverty of the stimulus, the physicalist conception of the stimulus, and the passive character of the perceiver of mainstream theories of perception. On the contrary, the main principles of ecological psychology are the continuity of perception and action, the organism-environment system as unit of analysis, the study of affordances as the objects of perception, combined with an emphasis on perceptual learning and development. In this paper, first, we analyze the philosophical and psychological influences of ecological psychology: pragmatism, behaviorism, phenomenology, and Gestalt psychology. Second, we summarize the main concepts of the approach and their historical development following the academic biographies of the proponents. Finally, we highlight the most significant developments of this psychological tradition. We conclude that ecological psychology is one of the most innovative approaches in the psychological field, as it is reflected in its current influence in the contemporary embodied and situated cognitive sciences, where the notion of affordance and the work of E. J. Gibson and J. J. Gibson is considered as a historical antecedent.This study was supported by a 2018 Leonardo Grant for Researchers and Cultural Creators, BBVA Foundation (the foundation accepts no responsibility for the opinions, statements and contents included in the project, and/or the results thereof, which are entirely the responsibility of the authors), the Projects PSI2013-43742 and FFI2016-80088-P funded by the Spanish Ministry of Science and the FiloLab Group of Excellence, Spain funded by the Universidad de Granada, Spain.2018-1

A Methodology Based on Bioacoustic Information for Automatic Identification of Reptiles and Anurans

Nowadays, human activity is considered one of the main risk factors for the life of reptiles and amphibians. The presence of these living beings represents a good biological indicator of an excellent environmental quality. Because of their behavior and size, most of these species are complicated to recognize in their living environment with image devices. Nevertheless, the use of bioacoustic information to identify animal species is an efficient way to sample populations and control the conservation of these living beings in large and remote areas where environmental conditions and visibility are limited. In this chapter, a novel methodology for the identification of different reptile and anuran species based on the fusion of Mel and Linear Frequency Cepstral Coefficients, MFCC and LFCC, is presented. The proposed methodology has been validated using public databases, and experimental results yielded an accuracy above 95% showing the efficiency of the proposal

Height after side: Goalkeepers detect the vertical direction of association-football penalty kicks from the ball trajectory

The present research analyzes the relation between the height of penalty kicks in association football and (a) the probability that goalkeepers stop the ball, (b) the kinematics of the kicker, and (c) the movements of the goalkeeper. We re-analyzed movement registration data that were collected in an experiment (with professional and semi-professional players) that focused on the horizontal direction of the penalties (Lopes et al., 2014). We also digitized and analyzed regular videos of the goalkeepers that were recorded by Lopes et al. (2014) but not analyzed. The present research complements the current understanding of the penalty kick with three main observations. First, goalkeepers save penalties at middle heights more often than low and high penalties. Second, the height of penalties is predicted less clearly than their horizontal direction from the kinematics of penalty takers. Third, goalkeepers tend to initiate the horizontal component of the saving action before the penalty taker contacts the ball, but they initiate the vertical component of the action about 245 ms after the contact. Taken together, these results support the view that goalkeepers make the left-right decision at least partly focusing on the kinematics of the kicker, and that they dynamically decide the vertical aspects of the movement later, focusing on the ball trajectory.This research was supported by a grant from the Portuguese Foundation for Science and Technology (SFRH/BD/60520/2009), awarded to JL, and a grant from the Spanish Ministry of Economy and Competitiveness (PSI2013-43742). DA was partly supported by the Fundação para a Ciência e Tecnologia, under Grant UIDB/00447/2020 to CIPER – Centro Interdisciplinar para o Estudo da Performance Humana (unit 447)

Accelerating networks

Evolving out-of-equilibrium networks have been under intense scrutiny recently. In many real-world settings the number of links added per new node is not constant but depends on the time at which the node is introduced in the system. This simple idea gives rise to the concept of accelerating networks, for which we review an existing definition and -- after finding it somewhat constrictive -- offer a new definition. The new definition provided here views network acceleration as a time dependent property of a given system, as opposed to being a property of the specific algorithm applied to grow the network. The defnition also covers both unweighted and weighted networks. As time-stamped network data becomes increasingly available, the proposed measures may be easily carried out on empirical datasets. As a simple case study we apply the concepts to study the evolution of three different instances of Wikipedia, namely, those in English, German, and Japanese, and find that the networks undergo different acceleration regimes in their evolution.Comment: 12 pages, 8 figure

Dynamic Touch as Common Ground for Enactivism and Ecological Psychology

The main purpose of this article is to show that enactivism and ecological psychology share more aspects than is often recognized. Rather than debating about differences, commonalities between the approaches are illustrated with the example of dynamic touch. Dynamic touch is a form of touch that implies muscles and tendons and that allows the perception of hand-held objects that are wielded but not seen. Given that perceivers perform the wielding movements with effort, dynamic touch necessarily implies active exploration. The strength of dynamic touch as an example lies in the fact that it has been formalized and analyzed in detail at the level of the laws that govern the organism-environment system. The example provides empirically supported instantiations of sensorimotor contingencies, in enactivist terms, and of intentional exploration and information detection, in ecological terms. Moreover, dynamic touch is a practical example of the enactivist concepts of bringing-forth the world and sense-making. As a second purpose, we use the example of dynamic touch to clarify key concepts of the ecological approach. Specifically, we analyze the concepts of invariance and affordance, indicating the crucial difference between perceiving and actualizing affordances, and highlighting the importance of these concepts for the dialogue between enactivism and ecological psychology.2019-2