1,720,985 research outputs found
EEG indices of performance monitoring activity and error predictability: embodying the actions of an avatar in immersive virtual reality
No full textElectro-cortical signatures of performance errors are thought to indicate the need for top-down control. Mid-frontal Theta oscillatory activity (4-8Hz) is a well-established marker of committed or observed errors. By combining EEG and immersive virtual reality, we reported that observing errors in reach-to-grasp actions of an avatar seen from a first-person perspective elicited greater theta oscillations over fronto-central electrodes (Pavone et al., 2016). Previous studies on committed or observed errors used sequences of trials were erroneous actions were less frequent than correct actions (e.g. 30% vs 70%). Therefore, it was not possible to disentangle whether the activation of the performance system was due to error per se or to surprise/novelty effect associated with rare and less predictable events. To address this issue, we recorded the EEG signal of 20 participants observing correct or erroneous actions performed by an avatar. Importantly, at variance with Pavone et al, (2016) the proportion of erroneous vs correct actions was 70% vs 30%. The results show that observation of erroneous actions enhanced Theta power compared to correct actions. Our data suggest that error per se, and not its percentage of occurrence, triggered the activity of the performance monitoring system, likely with the aim of flexibly adapting actions to the challenges of the external environment
Body Form Modulates the Prediction of Human and Artificial Behaviour from Gaze Observation
Full text linkThe future of human-robot collaboration relies on people's ability to understand and predict robots' actions. The machine-like appearance of robots, as well as contextual information, may influence people's ability to anticipate the behaviour of robots. We conducted six separate experiments to investigate how spatial cues and task instructions modulate people's ability to understand what a robot is doing. Participants observed goal-directed and non-goal directed gaze shifts made by human and robot agents, as well as directional cues displayed by a triangle. We report that biasing an observer's attention, by showing just one object an agent can interact with, can improve people's ability to understand what humanoid robots will do. Crucially, this cue had no impact on people's ability to predict the upcoming behaviour of the triangle. Moreover, task instructions that focus on the visual and motor consequences of the observed gaze were found to influence mentalising abilities. We suggest that the human-like shape of an agent and its physical capabilities facilitate the prediction of an upcoming action. The reported findings expand current models of gaze perception and may have important implications for human-human and human-robot collaboration
Fusco G., Tidoni E. “Fenomenologia dell’illusione di movimento in pazienti con lesione midollare”. AIP 2015 - Rovereto, Italy, 10-12 September 2015
No full textFusco G., Tidoni E. “Fenomenologia dell’illusione di movimento in pazienti con lesione midollare”. AIP 2015 - Rovereto, Italy, 10-12 September 201
Functional role of the theory of mind network in integrating mentalistic prior information with action kinematics during action observation
Full text linkInferring intentions from verbal and nonverbal human behaviour is critical for everyday social life. Here, we combined Transcranial Magnetic Stimulation (TMS) with a behavioural priming paradigm to test whether key nodes of the Theory of Mind network (ToMn) contribute to understanding others' intentions by integrating prior knowledge about an agent with the observed action kinematics. We used a modified version of the Faked-Action Discrimination Task (FAD), a forced-choice paradigm in which participants watch videos of actors lifting a cube and judge whether the actors are trying to deceive them concerning the weight of the cube. Videos could be preceded or not by verbal description (prior) about the agent's truthful or deceitful intent. We applied single pulse TMS over three key nodes of the ToMn, namely dorsomedial prefrontal cortex (dmPFC), right posterior superior tem-poral sulcus (pSTS) and right temporo-parietal junction (rTPJ). Sham-TMS served as a control (baseline) condition. Following sham or rTPJ stimulation, we observed no consis-tent influence of priors on FAD performance. In contrast, following dmPFC stimulation, and to a lesser extent pSTS stimulation, truthful and deceitful actions were perceived as more deceptive only when the prior suggested a dishonest intention. These findings highlight a functional role of dmPFC and pSTS in coupling prior knowledge about deceptive intents with observed action kinematics in order to judge faked actions. Our study provides causal evidence that fronto-temporal nodes of the ToMn are functionally relevant to mental state inference during action observation
Action simulation plays a critical role in deceptive action recognition
No full textThe ability to infer deception from nonverbal behavior is critical for social interactions. By combining single-pulse and repetitive transcranial magnetic stimulation (TMS), we provide correlational and causative evidence that action simulation is actively involved in the ability to detect deceptive behavior. We recorded motor-evoked potentials during a faked-action discrimination (FAD) task: participants watched videos of actors lifting a cube and judged whether the actors were trying to deceive them concerning the real weight of the cube. Seeing deceptive actions facilitated the observers’ motor system more than truthful actions, suggesting that motor resonance was sensitive to perceived deceits. Furthermore, we found that TMS disruption of inferior frontal cortex (IFC) but not of temporo-parietal junction (TPJ, control site) reduced perceptual sensitivity in the FAD-task. These findings indicate that IFC is necessary for inferring deceits from observed actions and suggest that FAD relies on the simulation of subtle changes in action kinematics
Freedom to act enhances the sense of agency, while movement and goal-related prediction errors reduce it
Full text linkThe Sense of Agency (SoA) is the experience of controlling one’s movements and their external consequences. Accumulating evidence suggests that freedom to act enhances SoA, while prediction errors are known to reduce it. Here, we investigated if prediction errors related to movement or to the achievement of the goal of the action exert the same influence on SoA during free and cued actions. Participants pressed a freely chosen or cued-colored button, while observing a virtual hand moving in the same or in the opposite direction—i.e., movement-related prediction error—and pressing the selected or a different color—i.e., goal-related prediction error. To investigate implicit and explicit components of SoA, we collected indirect (i.e., Synchrony Judgments) and direct (i.e., Judgments of Causation) measures. We found that participants judged virtual actions as more synchronous when they were free to act. Additionally, movement-related prediction errors reduced both perceived synchrony and judgments of causation, while goal-related prediction errors impaired exclusively the latter. Our results suggest that freedom to act enhances SoA and that movement and goal-related prediction errors lead to an equivalent reduction of SoA in free and cued actions. Our results also show that the influence of freedom to act and goal achievement may be limited, respectively, to implicit and explicit SoA, while movement information may affect both components. These findings provide support to recent theories that view SoA as a multifaceted construct, by showing that different action cues may uniquely influence the feeling of control
Simulating the Future of Actions in the Human Corticospinal System
No full textPerception of the final position of a moving object or creature is distorted forward along its actual or implied motion path, thus enabling anticipation of its forthcoming position. In a previous research, we demonstrated that viewing static snapshots that imply body actions activates the human motor system. What remains unknown, however, is whether extrapolation of dynamic information and motor activation are higher for upcoming than past action phases. By using single-pulse transcranial magnetic stimulation, we found that observation of start and middle phases of grasp and flick actions engendered a significantly higher motor facilitation than observing their final postures. Differential motor facilitation during start and end postures was independent of finger configuration at the different hand apertures. Subjective ratings showed that modulation of motor facilitation was not due to the amount of implied motion per se but to the forward direction of the motion path toward upcoming phases. Thus, motor facilitation proved maximal for the snapshots evoking ongoing but incomplete actions. The results provide compelling evidence that the frontal component of the observation--execution matching system is preferentially activated by the anticipatory simulation of future action phases and thus plays an important role in the predictive coding of others’ motor behaviors
Brain Dynamics of Action Monitoring in Higher-Order Motor Control Disorders: The Case of Apraxia
Full text linkLimb apraxia (LA) refers to a high-order motor disorder characterized by the inability to reproduce transitive actions on commands or after observation. Studies demonstrate that action observation and action execution activate the same networks in the human brain, and provides an onlooker's motor system with appropriate cognitive, motor and sensory-motor cues to flexibly implementing action-sequences and gestures. Tellingly, the temporal dynamics of action monitoring has never been explored in people suffering from LA. To fill this gap, we studied the electro-cortical signatures of error observation in human participants suffering from acquired left-brain lesions with (LA+) and without (LA-) LA, and in a group of healthy controls (H). EEG was acquired while participants observed from a first-person perspective (1PP) an avatar performing correct or incorrect reach-to-grasp a glass action in an immersive-virtual environment. Alterations of typical EEG signatures of error observation in time (early error positivity; Pe) and time-frequency domain (theta band-power) were found reduced in LA+ compared with H. Connectivity analyses showed that LA+ exhibited a decreased theta phase synchronization of both the frontoparietal and frontofrontal network, compared with H and LA-. Moreover, linear regression analysis revealed that the severity of LA [test of upper LA (TULIA) scores] was predicted by mid-frontal error-related theta activity, suggesting a link between error monitoring capacity and apraxic phenotypes. These results provide novel neurophysiological evidence of altered neurophysiological dynamics of action monitoring in individuals with LA and shed light on the performance monitoring changes occurring in this disorder
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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