Kahl S, Kopp S. Distinguishing minds in interaction: Modeling self-other distinction in the motor system. Presented at the 3rd Workshop on Virtual Social Interaction, Bielefeld

Kahl, Sebastian 

Kopp, Stefan 

Publications at Bielefeld University

Distinguishing minds in interaction: Modelingself-other distinction in the motor systemSebastian Kahl and Stefan KoppSocial Cognitive Systems Group, Faculty of Technology,Bielefeld University, Inspiration 1, 33619 Bielefeld, Germany{skahl,skopp}@uni-bielefeld.deIn order to engage in a continuous social interaction, participants must beable to dynamically understand, predict, and influence each other’s mental statesand actions, so as to enable a process of efficient and interactive grounding ofshared meaning. We follow the argument that the mentalizing network and themirror-neuron system in our social brain together provide the basis for theseabilities [1]. However, how these systems exactly operate and how they worktogether is still unclear. Building on previous work on the interplay of mental-izing and mirroring in embodied communication, here we lay out our modelingapproach together with simulation results that show how to solve the problem ofself-other distinction in a model of the sensorimotor system of interacting agents.We believe this to be an important step that informs mentalizing, so that in thefuture virtual agents equipped with this model can distinguish between own andother’s mental states in complex social situations.In a first step towards this goal, we developed a model of two distinct net-works of the human social brain - mentalizing and mirroring - which allows themto interact during embodied communication. The model connects a mentalizingsystem based on simple heuristics for attributing and inferring different ordersof belief about own and other’s mental states, with a hierarchical predictive pro-cessing model of online action perception and production based on the commoncoding of underlying action representations [2]. To investigate the role of men-talizing and mirroring interacting in inter-agent coordination and to test themodel, we conducted simulation experiments in which two virtual agents wereeach equipped with this model. Different mentalizing capacity configurationswere tested, as well as different noise conditions, thus influencing the robustnessof the communication. The agents engage in non-verbal communication behaviorto which the embodied action representations in the mirroring system can res-onate because of their close coupling of perception and production, while takinguncertainty from noise into account. Resonating action representations informthe mentalizing system, which in turn can guide successful interaction. Resultsfrom our simulations on this first model demonstrate how mentalizing can affordhigher robustness of communication by enabling interactive grounding processes.Although our model was able to act upon and infer beliefs about own andother’s mental states, it could only produce or perceive an action at a time. Ofcourse, this is a special case of interaction that can occur, but in our dynamicworld our social brain has to cope with concurrent production and perception2 Sebastian Kahl and Stefan Koppsituations, e.g., dancing with a partner or playing a duet on the piano. Situa-tions where you have to simultaneously keep track of your own actions whilecoordinating with your interaction partner’s actions, all using the same sensori-motor processes. Thus, as a starting point for an account of simultaneous actionand perception, the first step is to enable early self-other distinction within thesensorimotor system, which we will use to distinguish ourselves from others sothat we do not falsely attribute an action outcome to ourselves. As research intoschizophrenia has shown, reliable and early self-other integration and distinctionis important not only for the correct attribution of a sense of agency, but alsofor the correct attribution of intentions and emotions in social interactions [3].We modeled two processes that have been identified in the literature, whichtogether can be integrated into a combined sense of agency. The predictiveprocess makes use of people’s ability to anticipate the sensory consequences oftheir own actions. One account to model these processes is based on inverse andforward models [4]. The second, postdictive process uses higher-level causalbeliefs like the intention to act [5] and temporal binding as mechanisms to inferthe consistency of the action outcome. The “temporal binding window” [6] de-scribes the integration of sensory signals from multiple modalities, which selectsperceived actions and their outcomes for integration as long as they occur withina narrow temporal window. Because we have more experience in predicting ourown body that window is more narrow for own action-outcomes than for otherpeople’s actions. Being able to make such a distinction allows people to monitor,infer and distinguish between causal relations for own and other’s behavior.But how do these two processes work together to inform a sense of agencyand what if cues for agency are unreliable? We extended our prediction-basedmodel of the sensorimotor system with a model of self-other distinction basedon postdictive and predictive cues and compared two ways of cue integration tothe literature on the sense of agency. In the predictive process, we modeled thematch or mismatch of the predicted action-outcome. In the postdictive process,we modeled the intention to act and the delay in the action-outcome for temporalbinding (see [7] for more detail). It is not obvious from the literature how thecues from the predictive and postdictive processes are being integrated. As a firststep, we test two simple ways to do so, namely, to connect them conjunctively ordisjunctively. A conjunctive connection would allow a sense of agency to occuronly if it is supported by both processes; in a disjunctive connection only onecue would suffice to inform a sense of agency, in a more flexible but also moreerror prone manner.To test the extended model’s ability to differentiate between self and other wesimulated a social situation. In this situation, the model writes a character froma learned set of handwritten characters of the alphabet while it either receivesthe correct action-outcome as feedback, or it receives delayed or different feed-back than expected. This way we simulate the effect of simultaneously perceivingan interaction partner’s action. We tested three scenarios for each combinationto logically connect predictive and postdictive cues to form a sense of agency. Inthe first scenario we trigger the intent to act out a motor schema and the modelModeling self-other distinction in the motor system 3will perceive its own correct output as feedback. Here, the model receives bothcues correctly. In the second scenario we trigger the same intent to act, but themodel now receives its output with a delay, disrupting the postdictive cue. Inthe third scenario the model again is triggered to act, while this time it receivesunpredicted action-outcomes.Results from these simulations show that a disjunctive connection betweencues fares better, since it allows for a sense of agency even in dynamic scenariosof simultaneous perception and production, with feedback either from own orfrom other’s actions. This more flexible distinction is also supported by resultsreported in the literature, e.g., [8] found that where the reliability of the predic-tive process was reduced, the system put more weight on the post-hoc inferentialprocesses. Taken together, our modeling approach supports the motor system’srole in social cognition. In future work we want to use the differentiating infor-mation provided by the present model to inform higher-level cognition throughan interplay with the mentalizing system, to prepare virtual agents to distinguishbetween own and other’s mental states in complex social situations.Acknowledgements This research/work was supported by the Cluster of Ex-cellence Cognitive Interaction Technology ’CITEC’ (EXC 277) at Bielefeld Uni-versity, which is funded by the German Research Foundation (DFG).References1. Schilbach, L., Timmermans, B., Reddy, V., Costall, A., Bente, G., Schlicht, T.,Vogeley, K.: Toward a second-person neuroscience. Behav Brain Sci. 36, 393414(2013).2. Kahl, S., Kopp, S.: Towards a Model of the Interplay of Mentalizing and Mirroringin Embodied Communication. In: Airenti, G., Bara, B.G., and Sandini, G. (eds.)Proceedings of the EuroAsianPacific Joint Conference on Cognitive Science. 1419,p. 300-305. (2015).3. van der Weiden, A., Prikken, M., van Haren, N.E.M.: Self-other integration anddistinction in schizophrenia: A theoretical analysis and a review of the evidence.Neuroscience and Biobehavioral Reviews. 57, 220237 (2015).4. Frith, C. D., Blakemore, & Wolpert, D. M. (2000). Abnormalities in the awarenessand control of action. Philosophical Transactions of the Royal Society B: BiologicalSciences, 355(1404), 17711788.5. Wegner, D. M., & Wheatley, T. (1999). Apparent mental causation. Sources of theexperience of will. American Psychologist, 54(7), 480492.6. Colonius, H., Diederich, A.: Multisensory Interaction in Saccadic Reaction Time:A Time-Window-of-Integration Model. Journal of Cognitive Neuroscience. 16,10001009 (2004).7. Kahl, S., & Kopp, S. (Accepted). Self-other distinction in the motor system duringsocial interaction: A computational model based on predictive processing. Presentedat the 39th Annual Meeting of the Cognitive Science Society (CogSci 2017).8. Wolpe, N., Moore, J. W., Rae, C. L., Rittman, T., Altena, E., Haggard, P., & Rowe,J. B. (2014). The medial frontal-prefrontal network for altered awareness and controlof action in corticobasal syndrome. Brain, 137(1), 208220.

Distinguishing minds in interaction: Modeling self-other distinction in the motor system

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Distinguishing minds in interaction: Modeling self-other distinction in the motor system

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