Violating body movement semantics: Neural signatures of self-generated and external-generated errors

Abstract

How do we recognize ourselves as the agents of our actions? Do we use the same error detection mechanisms to monitor self-generated vs. externally imposed actions? Using event-related brain potentials (ERPs), we identified two different error-monitoring loops involved in providing a coherent sense of the agency of our actions. In the first ERP experiment, the participants were embodied in a virtual body (avatar) while performing an error-prone fast reaction time task. Crucially, in certain trials, participants were deceived regarding their own actions, i.e., the avatar movement did not match the participant's movement. Self-generated real errors and false (avatar) errors showed very different ERP signatures and with different processing latencies: while real errors showed a classical frontal-central error-related negativity (Ne/ERN), peaking 100ms after error commission, false errors elicited a larger and delayed parietal negative component (at about 350-400ms). The violation of the sense of agency elicited by false avatar errors showed a strong similarity to ERP signatures related to semantic or conceptual violations (N400 component). In a follow-up ERP control experiment, a subset of the same participants merely acted as observers of the avatar correct and error movements. This experimental situation did not elicit the N400 component associated with agency violation. Thus, the results show a clear neural dissociation between internal and external error-monitoring loops responsible for distinguishing our self-generated errors from those imposed externally, opening new avenues for the study of the mental processes underlying the integration of internal and sensory feedback information while being actors of our own actions.

Stereoscopic First Person View System for Drone Navigation

“…This is congruent with previous findings (Stanney and Hash, 1998). We hypothesize that intentional action-binding mechanisms played a key role during the real-time condition (Haggard et al, 2002;Padrao et al, 2016). Furthermore, tolerance in perceivable latencies for participants of the real-time condition is also explainable through those mechanisms (Haggard et al, 2002).…”

“…Postural stability can also modulate the prevalence of sickness, being more under control when participants are sitting rather than standing (Stoffregen et al, 2000). In general, VR navigation induces mismatched motion, which is internally related to incongruent multisensory processing in the brain Padrao et al, 2016). Indeed, to provide a coherent FPV in VR, congruent somatosensory stimulation and small latencies are needed, i.e., as the head rotates so does the rendering (SanchezVives and Slater, 2005;Gonzalez-Franco et al, 2010).…”

Avatar Embodiment. Towards a Standardized Questionnaire

“…It is important to emphasize how radically different the effects of the experience can be depending on the degrees of embodiment that participants experience. Aspects such as participant's behavior or their physiology are heavily influenced by the embodiment score (González-Franco et al, 2014;Padrao et al, 2016;Slater and Sanchez-Vives, 2016). The embodiment itself can be modulated by the type, race and look of the avatar participants embody (Hershfield et al, 2011;Kilteni et al, 2013;Peck et al, 2013).…”

“…Even though the evaluation of a perceptual illusion via a subjective questionnaire that is delivered after the fact may not render the best results (Slater, 2004), questionnaires are still the most prevalent metric, due to versatility and ease of use. Additionally, several embodiment experiments that use questionnaires as well as quantitative measures have shown correlations between the objective effects of the experiment and the subjective embodiment levels of the participants as extracted from the questionnaires (González-Franco et al, 2014;Padrao et al, 2016). Therefore, comprehensive questionnaires may render a reasonable embodiment measure.…”

Immersive Mixed Reality for Manufacturing Training

“…In this context, VR has successfully reproduced classical moral dilemmas to find out how people react without compromising their integrity (Slater et al, 2006;Friedman et al, 2014). Similarly, these realistic behaviors can also influence training, and several authors have already used VR as a tool for training and rehearsal in medical situations (Seymour et al, 2002;von Websky et al, 2013), disaster relief training (Farra et al, 2013), and other skill trainings related to motor control (Kishore et al, 2014;Padrao et al, 2016). However, while VR may be an excellent approach for isolated training, it is increasingly complex to use for collaborative training or faceto-face setups (Churchill and Snowdon, 1998;Monahan et al, 2008;Bourdin et al, 2013;Gonzalez-Franco et al, 2015).…”