294 research outputs found
The Social Cognitive Actor
Multi-Agent Simulation (MAS) of organisations is a methodology that is adopted in this dissertation in order to study and understand human behaviour in organisations.
The aim of the research is to design and implementat a cognitive and social multi-agent simulation model based on a selection of social and cognitive theories to fulfill the need for a complex cognitive and social model. The emphasis of this dissertation is the relationship between behaviour of individuals (micro-level) in an organisation and the behaviour of the organisation as a whole (macro-level)
Neural Network Based Reinforcement Learning for Audio-Visual Gaze Control in Human-Robot Interaction
This paper introduces a novel neural network-based reinforcement learning
approach for robot gaze control. Our approach enables a robot to learn and to
adapt its gaze control strategy for human-robot interaction neither with the
use of external sensors nor with human supervision. The robot learns to focus
its attention onto groups of people from its own audio-visual experiences,
independently of the number of people, of their positions and of their physical
appearances. In particular, we use a recurrent neural network architecture in
combination with Q-learning to find an optimal action-selection policy; we
pre-train the network using a simulated environment that mimics realistic
scenarios that involve speaking/silent participants, thus avoiding the need of
tedious sessions of a robot interacting with people. Our experimental
evaluation suggests that the proposed method is robust against parameter
estimation, i.e. the parameter values yielded by the method do not have a
decisive impact on the performance. The best results are obtained when both
audio and visual information is jointly used. Experiments with the Nao robot
indicate that our framework is a step forward towards the autonomous learning
of socially acceptable gaze behavior.Comment: Paper submitted to Pattern Recognition Letter
Computational and Psycho-Physiological Investigations of Musical Emotions
The ability of music to stir human emotions is a well known fact (Gabrielsson & Lindstrom.
2001). However, the manner in which music contributes to those experiences remains
obscured. One of the main reasons is the large number of syndromes that characterise
emotional experiences. Another is their subjective nature: musical emotions can be
affected by memories, individual preferences and attitudes, among other factors (Scherer
& Zentner, 2001). But can the same music induce similar affective experiences in all
listeners, somehow independently of acculturation or personal bias? A considerable
corpus of literature has consistently reported that listeners agree rather strongly about
what type of emotion is expressed in a particular piece or even in particular moments or
sections (Juslin & Sloboda, 2001). Those studies suggest that music features encode
important characteristics of affective experiences, by suggesting the influence of various
structural factors of music on emotional expression. Unfortunately, the nature of these
relationships is complex, and it is common to find rather vague and contradictory
descriptions.
This thesis presents a novel methodology to analyse the dynamics of emotional
responses to music. It consists of a computational investigation, based on spatiotemporal
neural networks sensitive to structural aspects of music, which "mimic" human affective
responses to music and permit to predict new ones. The dynamics of emotional
responses to music are investigated as computational representations of perceptual
processes (psychoacoustic features) and self-perception of physiological activation
(peripheral feedback). Modelling and experimental results provide evidence suggesting
that spatiotemporal patterns of sound resonate with affective features underlying
judgements of subjective feelings. A significant part of the listener's affective response
is predicted from the a set of six psychoacoustic features of sound - tempo, loudness,
multiplicity (texture), power spectrum centroid (mean pitch), sharpness (timbre) and
mean STFT flux (pitch variation) - and one physiological variable - heart rate. This work
contributes to new evidence and insights to the study of musical emotions, with particular
relevance to the music perception and emotion research communities
Drama, a connectionist model for robot learning: experiments on grounding communication through imitation in autonomous robots
The present dissertation addresses problems related to robot learning from demonstraÂŹ
tion. It presents the building of a connectionist architecture, which provides the robot
with the necessary cognitive and behavioural mechanisms for learning a synthetic lanÂŹ
guage taught by an external teacher agent. This thesis considers three main issues:
1) learning of spatio-temporal invariance in a dynamic noisy environment, 2) symbol
grounding of a robot's actions and perceptions, 3) development of a common symbolic
representation of the world by heterogeneous agents.We build our approach on the assumption that grounding of symbolic communication
creates constraints not only on the cognitive capabilities of the agent but also and especially on its behavioural capacities. Behavioural skills, such as imitation, which allow
the agent to co-ordinate its actionn to that of the teacher agent, are required aside to
general cognitive abilities of associativity, in order to constrain the agent's attention
to making relevant perceptions, onto which it grounds the teacher agent's symbolic
expression. In addition, the agent should be provided with the cognitive capacity for
extracting spatial and temporal invariance in the continuous flow of its perceptions.
Based on this requirement, we develop a connectionist architecture for learning time
series. The model is a Dynamical Recurrent Associative Memory Architecture, called
DRAMA. It is a fully connected recurrent neural network using Hebbian update rules.
Learning is dynamic and unsupervised. The performance of the architecture is analysed theoretically, through numerical simulations and through physical and simulated
robotic experiments. Training of the network is computationally fast and inexpensive,
which allows its implementation for real time computation and on-line learning in a
inexpensive hardware system. Robotic experiments are carried out with different learning tasks involving recognition of spatial and temporal invariance, namely landmark
recognition and prediction of perception-action sequence in maze travelling.The architecture is applied to experiments on robot learning by imitation. A learner
robot is taught by a teacher agent, a human instructor and another robot, a vocabulary
to describe its perceptions and actions. The experiments are based on an imitative
strategy, whereby the learner robot reproduces the teacher's actions. While imitating
the teacher's movements, the learner robot makes similar proprio and exteroceptions
to those of the teacher. The learner robot grounds the teacher's words onto the set of
common perceptions they share. We carry out experiments in simulated and physical
environments, using different robotic set-ups, increasing gradually the complexity of
the task. In a first set of experiments, we study transmission of a vocabulary to
designate actions and perception of a robot. Further, we carry out simulation studies,
in which we investigate transmission and use of the vocabulary among a group of
robotic agents. In a third set of experiments, we investigate learning sequences of the
robot's perceptions, while wandering in a physically constrained environment. Finally,
we present the implementation of DRAMA in Robota, a doll-like robot, which can
imitate the arms and head movements of a human instructor. Through this imitative
game, Robota is taught to perform and label dance patterns. Further, Robota is taught
a basic language, including a lexicon and syntactical rules for the combination of words
of the lexicon, to describe its actions and perception of touch onto its body
What Is Cognitive Psychology?
What Is Cognitive Psychology? identifies the theoretical foundations of cognitive psychologyâfoundations which have received very little attention in modern textbooks. Beginning with the basics of information processing, Michael R. W. Dawson explores what experimental psychologists infer about these processes and considers what scientific explanations are required when we assume cognition is rule-governed symbol manipulation. From these foundations, psychologists can identify the architecture of cognition and better understand its role in debates about its true nature. This volume offers a deeper understanding of cognitive psychology and presents ideas for integrating traditional cognitive psychology with more modern fields like cognitive neuroscience.Publishe
The 1995 Goddard Conference on Space Applications of Artificial Intelligence and Emerging Information Technologies
This publication comprises the papers presented at the 1995 Goddard Conference on Space Applications of Artificial Intelligence and Emerging Information Technologies held at the NASA/Goddard Space Flight Center, Greenbelt, Maryland, on May 9-11, 1995. The purpose of this annual conference is to provide a forum in which current research and development directed at space applications of artificial intelligence can be presented and discussed
Imitation and social learning for synthetic characters
Thesis (S.M.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2004.Includes bibliographical references (p. 137-149).We want to build animated characters and robots capable of rich social interactions with humans and each other, and who are able to learn by observing those around them. An increasing amount of evidence suggests that, in human infants, the ability to learn by watching others, and in particular, the ability to imitate, could be crucial precursors to the development of appropriate social behavior, and ultimately the ability to reason about the thoughts, intents, beliefs, and desires of others. We have created a number of imitative characters and robots, the latest of which is Max T. Mouse, an anthropomorphic animated mouse character who is able to observe the actions he sees his friend Morris Mouse performing, and compare them to the actions he knows how to perform himself. This matching process allows Max to accurately imitate Morris's gestures and actions, even when provided with limited synthetic visual input. Furthermore, by using his own perception, motor, and action systems as models for the behavioral and perceptual capabilities of others (a process known as Simulation Theory in the cognitive literature), Max can begin to identify simple goals and motivations for Morris's behavior, an important step towards developing characters with a full theory of mind. Finally, Max can learn about unfamiliar objects in his environment, such as food and toys, by observing and correctly interpreting Morris's interactions with these objects, demonstrating his ability to take advantage of socially acquired information.by Daphna Buchsbaum.S.M
Computational Methods for Cognitive and Cooperative Robotics
In the last decades design methods in control engineering made substantial progress in
the areas of robotics and computer animation. Nowadays these methods incorporate the
newest developments in machine learning and artificial intelligence. But the problems
of flexible and online-adaptive combinations of motor behaviors remain challenging for
human-like animations and for humanoid robotics. In this context, biologically-motivated
methods for the analysis and re-synthesis of human motor programs provide new insights
in and models for the anticipatory motion synthesis.
This thesis presents the authorâs achievements in the areas of cognitive and developmental robotics, cooperative and humanoid robotics and intelligent and machine learning methods in computer graphics. The first part of the thesis in the chapter âGoal-directed Imitation for Robotsâ considers imitation learning in cognitive and developmental robotics.
The work presented here details the authorâs progress in the development of hierarchical
motion recognition and planning inspired by recent discoveries of the functions of mirror-neuron cortical circuits in primates. The overall architecture is capable of âlearning for
imitationâ and âlearning by imitationâ. The complete system includes a low-level real-time
capable path planning subsystem for obstacle avoidance during arm reaching. The learning-based path planning subsystem is universal for all types of anthropomorphic robot arms, and is capable of knowledge transfer at the level of individual motor acts.
Next, the problems of learning and synthesis of motor synergies, the spatial and spatio-temporal combinations of motor features in sequential multi-action behavior, and the
problems of task-related action transitions are considered in the second part of the thesis
âKinematic Motion Synthesis for Computer Graphics and Roboticsâ. In this part, a new
approach of modeling complex full-body human actions by mixtures of time-shift invariant
motor primitives in presented. The online-capable full-body motion generation architecture
based on dynamic movement primitives driving the time-shift invariant motor synergies
was implemented as an online-reactive adaptive motion synthesis for computer graphics
and robotics applications.
The last chapter of the thesis entitled âContraction Theory and Self-organized Scenarios
in Computer Graphics and Roboticsâ is dedicated to optimal control strategies in multi-agent scenarios of large crowds of agents expressing highly nonlinear behaviors. This last
part presents new mathematical tools for stability analysis and synthesis of multi-agent
cooperative scenarios.In den letzten Jahrzehnten hat die Forschung in den Bereichen der Steuerung und Regelung
komplexer Systeme erhebliche Fortschritte gemacht, insbesondere in den Bereichen
Robotik und Computeranimation. Die Entwicklung solcher Systeme verwendet heutzutage
neueste Methoden und Entwicklungen im Bereich des maschinellen Lernens und der
kĂŒnstlichen Intelligenz. Die flexible und echtzeitfĂ€hige Kombination von motorischen Verhaltensweisen
ist eine wesentliche Herausforderung fĂŒr die Generierung menschenĂ€hnlicher
Animationen und in der humanoiden Robotik. In diesem Zusammenhang liefern biologisch
motivierte Methoden zur Analyse und Resynthese menschlicher motorischer Programme
neue Erkenntnisse und Modelle fĂŒr die antizipatorische Bewegungssynthese.
Diese Dissertation prÀsentiert die Ergebnisse der Arbeiten des Autors im Gebiet der
kognitiven und Entwicklungsrobotik, kooperativer und humanoider Robotersysteme sowie
intelligenter und maschineller Lernmethoden in der Computergrafik. Der erste Teil der
Dissertation im Kapitel âZielgerichtete Nachahmung fĂŒr Roboterâ behandelt das Imitationslernen
in der kognitiven und Entwicklungsrobotik. Die vorgestellten Arbeiten beschreiben
neue Methoden fĂŒr die hierarchische Bewegungserkennung und -planung, die durch
Erkenntnisse zur Funktion der kortikalen Spiegelneuronen-Schaltkreise bei Primaten inspiriert
wurden. Die entwickelte Architektur ist in der Lage, âdurch Imitation zu lernenâ
und âzu lernen zu imitierenâ. Das komplette entwickelte System enthĂ€lt ein echtzeitfĂ€higes
Pfadplanungssubsystem zur Hindernisvermeidung wĂ€hrend der DurchfĂŒhrung von Armbewegungen.
Das lernbasierte Pfadplanungssubsystem ist universell und fĂŒr alle Arten von
anthropomorphen Roboterarmen in der Lage, Wissen auf der Ebene einzelner motorischer
Handlungen zu ĂŒbertragen.
Im zweiten Teil der Arbeit âKinematische Bewegungssynthese fĂŒr Computergrafik und
Robotikâ werden die Probleme des Lernens und der Synthese motorischer Synergien, d.h.
von rÀumlichen und rÀumlich-zeitlichen Kombinationen motorischer Bewegungselemente
bei Bewegungssequenzen und bei aufgabenbezogenen Handlungs ĂŒbergĂ€ngen behandelt.
Es wird ein neuer Ansatz zur Modellierung komplexer menschlicher Ganzkörperaktionen
durch Mischungen von zeitverschiebungsinvarianten Motorprimitiven vorgestellt. Zudem
wurde ein online-fĂ€higer Synthesealgorithmus fĂŒr Ganzköperbewegungen entwickelt, der
auf dynamischen Bewegungsprimitiven basiert, die wiederum auf der Basis der gelernten
verschiebungsinvarianten Primitive konstruiert werden. Dieser Algorithmus wurde fĂŒr
verschiedene Probleme der Bewegungssynthese fĂŒr die Computergrafik- und Roboteranwendungen
implementiert.
Das letzte Kapitel der Dissertation mit dem Titel âKontraktionstheorie und selbstorganisierte
Szenarien in der Computergrafik und Robotikâ widmet sich optimalen Kontrollstrategien
in Multi-Agenten-Szenarien, wobei die Agenten durch eine hochgradig nichtlineare
Kinematik gekennzeichnet sind. Dieser letzte Teil prÀsentiert neue mathematische Werkzeuge
fĂŒr die StabilitĂ€tsanalyse und Synthese von kooperativen Multi-Agenten-Szenarien
Backwards is the way forward: feedback in the cortical hierarchy predicts the expected future
Clark offers a powerful description of the brain as a prediction machine, which offers progress on two distinct levels. First, on an abstract conceptual level, it provides a unifying framework for perception, action, and cognition (including subdivisions such as attention, expectation, and imagination). Second, hierarchical prediction offers progress on a concrete descriptive level for testing and constraining conceptual elements and mechanisms of predictive coding models (estimation of predictions, prediction errors, and internal models)
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