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CONCEPTUALIZATION (WP2)

CONCEPTUALIZATION (WP2). Stefano Nolfi 1 , Tony Belpaeme 2 , Joachim De Greeff 2 , Frederic Delaunay 2 , Tomassino Ferraiuto 1 , Gianluca Massera 1 , Marco Mirolli 1 , Katharina Rohlfing 3 , Elio Tuci 1 , 1 Institute of Cognitive Sciences and Technologies, CNR 2 University of Plymouth (PLYM)

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CONCEPTUALIZATION (WP2)

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  1. CONCEPTUALIZATION (WP2) Stefano Nolfi1, Tony Belpaeme2, Joachim De Greeff2, Frederic Delaunay2, Tomassino Ferraiuto1, Gianluca Massera1, Marco Mirolli1, Katharina Rohlfing3, Elio Tuci1, 1Institute of Cognitive Sciences and Technologies, CNR 2University of Plymouth (PLYM) 3University of Bielefeld (BIEL)

  2. Introduction To properly interact with the physical and social environment, agents should be able to transform continuous signals perceived by sensory organs into internal states We term such internal states embodied concepts and we understand them as representations, grounded in sensory-motor experiences, that identify crucial aspects of the environment and/or of the agent/environmental relation Embodied concepts represents a prerequisites for important functions such us (producing different behaviors in functionally different situations, reasoning about past and future, interact linguistically with other agents). However, at the same time, they are the results of the co-development of such skills ITALK Year 1 Review, WP22

  3. WP2: Objective & Organization Objective: Study how embodied and situated agents develop embodied concepts while they attempt to develop the requested behavioral, linguistic, and social skills T2.1: Active categorical perception (CNR, IIT) T2.2: Cognitive and adaptive pre-requisite for grounding of abstract categories (CNR, PLYM) T2.3: Cognitive biases in category learning (PLYM) T2.4: Parameters, structure and use of semiotic schemas (PLYM) T2.5: Social interactions and category formation (BIEL, CNR) ITALK Year 1 Review, WP23

  4. T2.1: Active Categorical Perception in Artificial Embodied Agents Although the significance of embodiment and situatedness is now widely recognized, our ability to build artificial systems that are able to actively perceive and categorize sensory experiences is still very limited One promising approach, in this respect, is constituted by adaptive methods in which artificial agents adapt to their task/environment autonomously on the basis of a trial and error process ITALK Year 1 Review, WP24 T2.1

  5. Adaptive Methods Retaining or discarding variations on the basis of their effects at the level of the global behavior exhibited by the robot in interaction with the environment behavior behavior Introducing variations at the levels of the properties that regulate the fine-grained interaction between the robot and the environment behavior behavior behavior behavior Environment Body Nervous system The robot is left free to determine and to co-develop the behavioural and cognitive skills that it will exhibit at intermediate levels of organization ITALK Year 1 Review, WP25 T2.1

  6. Coordinating the sensory-motor processes so to experience discriminative stimuli 1/2 categorization motors proprio-sensors touch s. Nolfi & Marocco (2001) ITALK Year 1 Review, WP26 T2.1

  7. Coordinating the sensory-motor processes so to experience discriminative stimuli 2/2 Kato & Floreano (2001) ITALK Year 1 Review, WP27 T2.1

  8. Categorical perception of object shapes in asimulated anthropomorphic robotic arm sphere ellipsoid Selection criterion (reward): (1) producing non-overlapping categorization outputs for object with different shapes, and (2) touching the object. ITALK Year 1 Review, WP28 T2.1

  9. Behaviour exhibited by adapted robots Position A ITALK Year 1 Review, WP29 T2.1

  10. Behaviour exhibited by adapted robots Position A Optimal performance (over 16 trials) • Generalization: • 0.98% performance for objects placed in all possible orientations (3600 trials) • Good performance for objects placed in different positions Position B ITALK Year 1 Review, WP210 T2.1

  11. On the role of different sensory channels states of tactile sensors for spherical objects replaced with states for ellipsoid objects and viceversa Categorization is based on tactile and hand-propriosensor information For position B, the information provided by the tactile and the hand propriosensor channels are fused together in a way that allow to produce good performance (~75% correct answers) even when one or the other channel is replaced with contradictory information. ITALK Year 1 Review, WP211 T2.1

  12. On the dynamic of the categorization process 1/2 separation of stimuli in the input space number of fully ambiguous stimuli The behavior exhibited by the robot allow it to experience discriminative cues However it not allow to experience fully discriminative stimuli ITALK Year 1 Review, WP212 T2.1

  13. On the dynamic of the categorization process 2/2 decision taken integration over-time sensory-motor coordination Data substituted from the beginning to time step X Data substituted from time step X to the end • Categorization is accomplished by: • Active perception (sensory-motor coordination) • Integration of sensory-motor states experienced over time into internal states The integration of information over time is accomplished through a process of accumulation of partially conflicting evidences ITALK Year 1 Review, WP213 T2.1

  14. Categorization in an active vision system Selection criterion (reward): (1) activating the correct categorization output more than the other units (2) minimizing the activation of the other four units ITALK Year 1 Review, WP214 T2.1

  15. Behaviours exhibited by adapted individuals 1/3 ITALK Year 1 Review, WP215 T2.1

  16. Behaviours exhibited by adapted individuals 2/3 ITALK Year 1 Review, WP216 T2.1

  17. Behaviours exhibited by adapted individuals 3/3 ITALK Year 1 Review, WP217 T2.1

  18. On the role of different sensory channels In some experiments categorization is based primarily on the state of the fovea photoreceptors In other cases categorization is based primarily on the state of the efferent copy of the motors M1 : efferent copies of motors normalized between [0.1] M10: efferent copies of motors normalized between [0.10] ITALK Year 1 Review, WP218 T2.1

  19. On the dynamics of the categorization process • Categorization is accomplished by: • Active perception (sensory-motor coordination) • Integration of sensory-motor states experienced over time into internal states ITALK Year 1 Review, WP219 T2.1

  20. Accumulation of partially conflicting evidences over time Each type of stimulus is associated to a corresponding category/categories on the basis of the frequency with which it is experienced in the corresponding categorical context/contexts Few experienced stimuli are fully discriminative (i.e. are experienced in a given categorical context only) and therefore are associated to a single category Other stimuli are experienced in different categorical contexts and therefore might provide wrong evidences (i.e. might increase the activity of wrong categorical units) Overall, however, the summed contribution of the evidences provided by the recent experienced sensory stimuli ensures that the correct categorization unit reaches the highest activation level. ITALK Year 1 Review, WP220 T2.1 / T2.2

  21. Plan for future works Run experiments in which robots are rewarded only for the ability to perform a behaviour that require categorization (and not explicitly for categorizing). Study the development of abstract concepts (i.e. relational concept or concepts based on previously developed categories) Study how the development of categorization skills is influenced by sensory deprivation (i.e. by the fact that sensory information might be temporary missing or by the fact that the information provided by a given sensory channel might be temporary un-available). ITALK Year 1 Review, WP221 T2.1/T2.2

  22. T2.3 Cognitive biases and language in conceptualisation ITALK Year 1 Review, WP222 • Language impacts on concept acquisition: observed from infants to adults. • Xu, F. (2002). The role of language in acquiring object kind concepts in infancy. Cognition, 85, 223-250. • Plunkett, K., Hu, J. F., & Cohen, L. B. (2008). Labels can override perceptual categories in early infancy. Cognition, 106(2), 665-681. • Roberson, D., & Hanley, J. R. (2007). Color categories vary with language after all. Current Biology, 17, 605-606. • Naively, language can be seen as labels for perception. • However, language is special (see Luypan et al.) and allows for richer social interaction which aids concept acquisition. • Lupyan, G., Rakison, D. H., & McClelland, J. L. (2007). Language is not just for talking - Redundant labels facilitate learning of novel categories. Psychological Science, 18(12), 1077-1083. T2.3

  23. Concept acquisition under influence of language: a model ITALK Year 1 Review, WP223 Computational model to study interactive learning of concepts. Robotic experiments in which a robot has to learn labels and categories while interacting with a teacher (caretaker) T2.3

  24. Components of the model Agent Conceptual Space Prototype Context Topic ITALK Year 1 Review, WP224 • Conceptual space (based on Gärdenfors). • Geometrical representation. • Distance measure implementing prototype theory. • Learning model based on Language Games (Steels and Belpaeme). • Associating labels to perceptual information. • Acquiring concepts. T2.3

  25. Interactive learning ITALK Year 1 Review, WP225 • Novelty preference • learner enquires the caretaker about novel elements in the environment • Knowledge querying • Learner checks uncertain knowledge with teacher • Contrastive learning • Context is used as contrastive information T2.3

  26. Results ITALK Year 1 Review, WP226 T2.3

  27. Plan for future works ITALK Year 1 Review, WP227 • Study of different domains • Implementation of compositionality and hierarchy within conceptual space. T2.3

  28. T2.5 Social Interaction and category formation • Social interaction studies with 21 to 26 months old children: mothers instructed their children to put two things together (task-oriented dialogue) • planned analyses: How children acquire new relational categories? Are there „basic relations“? How can parents build upon what children know about events? • Hypothesis: Children‘s knowledge bias about objects and their canonical functions influences the interaction task bias ITALK Year 1 Review, WP228 T2.5

  29. Plan for future works • We plan to conduct additional studies involving a larger number of objects and relations and collection and analisys of longitudinal data • We plan to study how verbal and non-verbal interactions with a caretaker might facilitate the development of a categorization skills in robotic experiments ITALK Year 1 Review, WP229 T2.5

  30. Summary We elaborated a method through which embodied agents can develop non-trivial categorization skills by exploiting sensory-motor coordination and integration of information over time More specifically we demonstrated how simple active perception strategies based on the attempt to act so to experience discriminative stimuli can be extended and integrated with simple cognitive processes based on the accumulation of partially conflicting evidences We started to investigate how cognitive biases and social interactions might enhance agents’ categorization skills ITALK Year 1 Review, WP230

  31. Behaviour exhibited by adapted robots Position A Optimal performance (over 16 trials) • Generalization: • 0.98% performance for objects placed in all possible orientations (3600 trials) • Good performance for objects placed in different positions Position B ITALK Year 1 Review, WP231 T2.1

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