1,721,077 research outputs found
Intentional strategies that make co-actors more predictable: The case of signaling
No full textPickering & Garrod (P&G) explain dialogue dynamics in terms of forward modeling and prediction-by-simulation mechanisms. Their theory dissolves a strict segregation between production and comprehension processes, and it links dialogue to action-based theories of joint action. We propose that the theory can also incorporate intentional strategies that increase communicative success: for example, signaling strategies that help remaining predictable and forming common ground
The secret life of predictive brains: what's spontaneous activity for?
No full textBrains at rest generate dynamical activity that is highly structured in space and time. We suggest that spontaneous activity, as in rest or dreaming, underlies top-down dynamics of generative models. During active tasks, generative models provide top-down predictive signals for perception, cognition, and action. When the brain is at rest and stimuli are weak or absent, top-down dynamics optimize the generative models for future interactions by maximizing the entropy of explanations and minimizing model complexity. Spontaneous fluctuations of correlated activity within and across brain regions may reflect transitions between ‘generic priors’ of the generative model: low dimensional latent variables and connectivity patterns of the most common perceptual, motor, cognitive, and interoceptive states. Even at rest, brains are proactive and predictive
Active inference unifies intentional and conflict-resolution imperatives of motor control
No full textThe field of motor control has long focused on the achievement of external goals through action (e.g., reaching and grasping objects). However, recent studies in conditions of multisensory conflict, such as when a subject experiences the rubber hand illusion or embodies an avatar in virtual reality, reveal the presence of unconscious movements that are not goal-directed, but rather aim at resolving multisensory conflicts; for example, by aligning the position of a person’s arm with that of an embodied avatar. This second, conflict-resolution imperative of movement control did not emerge in classical studies of motor adaptation and online corrections, which did not allow movements to reduce the conflicts; and has been largely ignored so far in formal theories. Here, we propose a model of movement control grounded in the theory of active inference that integrates intentional and conflict-resolution imperatives. We present three simulations showing that the active inference model is able to characterize movements guided by the intention to achieve an external goal, by the necessity to resolve multisensory conflict, or both. Furthermore, our simulations reveal a fundamental difference between the (active) inference underlying intentional and conflict-resolution imperatives by showing that it is driven by two different (model and sensory) kinds of prediction errors. Finally, our simulations show that when movement is only guided by conflict resolution, the model incorrectly infers that is velocity is zero, as if it was not moving. This result suggests a novel speculative explanation for the fact that people are unaware of their subtle compensatory movements to avoid multisensory conflict. Furthermore, it can potentially help shed light on deficits of motor awareness that arise in psychopathological conditions
Space Perception by Visuokinesthetic Prediction
No full textSchenck W, Möller R. Space Perception by Visuokinesthetic Prediction. In: Pezzulo G, Butz MV, Sigaud O, Baldassarre G, eds. Proceedings of the Fourth Workshop on Anticipatory Behavior in Adaptive Learning Systems. Munich; 2008
Local high-frequency vibration therapy following eccentric exercises reduces muscle soreness perception and posture alterations in elite athletes
No full textPURPOSE:
Exercise-induced muscle damage produces painful sensations (delayed onset of muscle soreness, DOMS). DOMS causes compensatory postural adaptations, which in turn affect athletes' walking and running gait biomechanics. It is still debated whether the postural changes are due to impaired proprioception or pain perception. To disambiguate between these two contrasting hypotheses, we designed a study that tested post-exercise postural adjustments in two groups of athletes: a group who was administered a vibration therapy (VT), to attenuate pain perception, and a control group.
METHODS:
Thirty professional futsal players were tested on five different occasions: baseline, eccentric exercises (EE) session day, 24, 48 and 72 h after EE. Vibration therapy (120 Hz) was applied on legs muscles for 15 min in the experimental group, while no vibration was applied in the control group. The measurements included: isokinetic evaluation, stabilometric test, perceived soreness evaluation and serum levels of creatine kinase, and lactate dehydrogenase.
RESULTS:
48 h after EE, the control group showed changes in biomechanical parameters (antero-rotations of pelvis, p < 0.05). A substantial alteration in the hip kinematics was found, associated to a reduced contractile force (p < 0.01) and soreness perception. On the contrary, the VT group did not show any change in posture and pain perception. High-intensity VT decreases EE effects on muscle strength and DOMS.
CONCLUSIONS:
DOMS significantly changes athletes' posture; but postural changes disappear following a VT therapy that decreases pain perception. It is concluded that soreness perception is the main cause of postural changes and that its effects can be counteracted using VT therapy
What should I do next? Using shared representations to solve interaction problems
No full textStudies on how the social mind" works reveal that cognitive agents engaged in joint actions actively estimate and in uence another\u27s cognitive variables, and form shared representations with them. (How) do shared rep- resentations enhance coordination? In this paper we provide a probabilistic model of joint action that emphasizes how shared representations help solv- ing interaction problems. We focus on two aspects of the model. First, we discuss how shared representations permit to coordinate at the level of cog- nitive variables (beliefs, intentions and actions), and determine a coherent unfolding of execution and predictive processes in the brains of two agents. Second, we discuss the importance of signaling actions as part of a strategy for sharing representations and the active guidance of another\u27s actions to- wards the achievement of a joint goal. Furthermore, we present data from a human-computer experiment (the Tower Game) in which two agents (human and computer) have to build together a tower made of colored blocks, but only the human knows the constellation of the tower to be built (e.g., red- blue-red-blue-. . . ). We report evidence that humans use signaling strategies that take another\u27s uncertainty into consideration, and that in turn our model is able to use humans\u27 actions as cues to align" its representations and to select complementary actions
Training and Application of a Visual Forward Model for a Robot Camera Head
No full textSchenck W, Möller R. Training and Application of a Visual Forward Model for a Robot Camera Head. In: Butz MV, Sigaud O, Pezzulo G, Baldassarre G, eds. Anticipatory Behavior in Adaptive Learning Systems: From Brains to Individual and Social Behavior. Lecture Notes in Artificial Intelligence. Berlin, Heidelberg, New York: Springer; 2007: 153-169
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