PRINCIPLES of SYNTHETIC INTELLIGENCE Building Blocks for an Architecture of Motivated Cognition Joscha Bach, Universität Osnabrück Cover artwork by Alex Guillotte (based on a painting by Leonardo da Vinci), used with friendly permission of the artist. Principles of Synthetic Intelligence Building Blocks for an Architecture of Motivated Cognition Dissertation submitted in partial fulfillment of the requirements for the doctoral degree (PhD) in Cognitive Science at the Fachbereich Humanwissenschaften, Universität Osnabrück by Joscha Bach 30th of March 2007 Advisors: Prof. Dr. Hans-Dieter Burkhard Prof. Dr. Dietrich Dörner Prof. Dr. Kai-Uwe Kühnberger Abstract Computational models of cognitive functioning have become a thriving paradigm in Cognitive Science, yet they usually only emphasize problem solving and reasoning, or treat perception and motivation as isolated modules. A very promising approach towards a broader architecture of cognition is the Psi theory of Dietrich Dörner. By dealing with the integration of motivation and emotion with perceptual and reasoning processes and including grounded neuro-symbolic representations, it contributes to an integrated understanding of the mind. The Psi theory supplies a conceptual framework highlighting the interrelations between perception and memory, language and mental representation, reasoning and motivation, emotion and cognition, autonomy and social behavior. However, its origin in psychology, its methodology and the lack of documentation have limited its impact to cognitive modeling. This work adapts the Psi theory to Cognitive Science and Artificial Intelligence, by summarizing and structuring it, by identifying its contribution to understanding cognition, and by providing a technical framework for implementing models of the theory. These goals are reflected in the three parts of this thesis. “Dörner’s Blueprint for a Mind” is a synopsis of the work of Dörner and his group. It reviews the available publications and implementations from the perspective of Cognitive Science and represents the statements and assumptions of the theory. “The Psi Theory as a Model of Cognition” briefly charts the domain of cognitive modeling and establishes the Psi theory’s position within this field, its contributions, limitations and some of its shortcomings. A special section focuses on computational models of emotion. One of the most interesting aspects of the theory is the suggestion of hierarchical neuro-symbolic representations which are grounded in a dynamic environment. These representations employ spreading activation mechanisms to act as associative memory, and they propose the combination of neural learning with symbolic reasoning and planning. “MicroPsi” is a comprehensive software framework designed to implement and execute models of the Psi theory as multi-agent systems. The final chapter introduces this framework and illustrates its application. Table of Contents 1 Dörner’s “blueprint for a mind” ...........................................................1 1.1 Introductory remarks ..........................................................................2 1.2 An Overview of the Psi Theory and Psi Agents .............................4 1.3 A simple autonomous vehicle .............................................................9 1.4 Representation of and for mental processes .................................12 1.4.1 Neural representation..........................................................................13 1.4.1.1 Neurons .....................................................................................13 1.4.1.2 Associators and dissociators......................................................14 1.4.1.3 Cortex fields, activators, inhibitors and registers ......................15 1.4.1.4 Sensor neurons and motor neurons............................................15 1.4.1.5 Sensors specific to cortex fields................................................15 1.4.1.6 Quads.........................................................................................16 1.4.2 Partonomies ........................................................................................19 1.4.3 Alternatives and subjunctions.............................................................20 1.4.4 Sensory schemas.................................................................................20 1.4.5 Effector/action schemas......................................................................21 1.4.6 Triplets................................................................................................22 1.4.7 Space and time....................................................................................23 1.4.8 Basic relationships..............................................................................24 1.5 Memory organization ........................................................................26 1.5.1 Episodic schemas................................................................................26 1.5.2 Behavior programs..............................................................................27 1.5.3 Protocol memory.................................................................................28 1.5.4 Abstraction and analogical reasoning .................................................31 1.5.5 Taxonomies.........................................................................................33 1.6 Perception .............................................................................................34 1.6.1 Expectation horizon............................................................................35 1.6.2 Orientation behavior ...........................................................................36 1.6.3 HyPercept ...........................................................................................36 1.6.3.1 How HyPercept works...............................................................36 1.6.3.2 Modification of HyPercept according to the Resolution Level .38 1.6.3.3 Generalization and Specialization.............................................39 1.6.3.4 Treating occlusions ...................................................................39 1.6.3.5 Assimilation of new objects into schemas.................................40 1.6.4 Situation image ...................................................................................41 1.6.5 Mental stage........................................................................................42 1.7 Managing knowledge .........................................................................42 1.7.1 Reflection (“Besinnung”)....................................................................42 iv Contents 1.7.2 Categorization (“What is it and what does it do?”).............................43 1.7.3 Symbol grounding...............................................................................44 1.8 Behavior control and action selection ............................................45 1.8.1 Appetence and aversion......................................................................46 1.8.2 Motivation...........................................................................................47 1.8.2.1 Urges.........................................................................................47 1.8.2.2 Motives......................................................................................47 1.8.2.3 Demands....................................................................................48 Fuel and water .........................................................................................48 Intactness (“Integrität”, integrity, pain avoidance) ..................................49 Certainty (“Bestimmtheit”, uncertainty reduction)..................................49 Competence (“Kompetenz”, efficiency, control).....................................50 Affiliation (“okayness”, legitimacy)........................................................51 1.8.2.4 Motive selection........................................................................53 1.8.3 Intentions ............................................................................................55 1.8.4 Action .................................................................................................55 1.8.4.1 Automatisms..............................................................................56 1.8.4.2 Simple Planning ........................................................................56 1.8.4.3 “What can be done?”—the Trial-and-error strategy..................58 1.8.5 Modulators..........................................................................................58 1.8.5.1 Activation/Arousal ....................................................................59 1.8.5.2 Selection threshold....................................................................59 1.8.5.3 Resolution level.........................................................................60 1.8.5.4 Sampling rate/securing behavior...............................................60 1.8.5.5 The dynamics of modulation.....................................................61 1.9 Emotion .................................................................................................63 1.9.1 Emotion as modulation.......................................................................64 1.9.2 Emotion and motivation......................................................................64 1.9.3 Emotional phenomena that are modeled by the Psi theory .................65 1.10 Language and Future