114 research outputs found
Corrigendum: Reduced mu power in response to unusual actions is context-dependent in 1-year-olds
During social interactions infants predict and evaluate other peopleâs actions. Previous behavioral research found that infantsâ imitation of othersâ actions depends on these evaluations and is context-dependent: 1-year-olds predominantly imitated an unusual action (turning on a lamp with oneâs forehead) when the modelâs hands were free compared to when the modelâs hands were occupied or restrained. In the present study, we adapted this behavioral paradigm to a neurophysiological study measuring infantsâ brain activity while observing usual and unusual actions via electroencephalography. In particular, we measured differences in mu power (6 â 8 Hz) associated with motor activation. In a between-subjects design, 12- to 14-month-old infants watched videos of adult models demonstrating that their hands were either free or restrained. Subsequent test frames showed the models turning on a lamp or a soundbox by using their head or their hand. Results in the hands-free condition revealed that 12- to 14-month-olds displayed a reduction of mu power in frontal regions in response to unusual and thus unexpected actions (head touch) compared to usual and expected actions (hand touch). This may be explained by increased motor activation required for updating prior action predictions in response to unusual actions though alternative explanations in terms of general attention or cognitive control processes may also be considered. In the hands-restrained condition, responses in mu frequency band did not differ between action outcomes. This implies that unusual head-touch actions compared to hand-touch actions do not necessarily evoke a reduction of mu power. Thus, we conclude that reduction of mu frequency power is context-dependent during infantsâ action perception. Our results are interpreted in terms of motor system activity measured via changes in mu frequency band as being one important neural mechanism involved in action prediction and evaluation from early on
Time reversal in thermoacoustic tomography - an error estimate
The time reversal method in thermoacoustic tomography is used for
approximating the initial pressure inside a biological object using
measurements of the pressure wave made on a surface surrounding the object.
This article presents error estimates for the time reversal method in the cases
of variable, non-trapping sound speeds.Comment: 16 pages, 6 figures, expanded "Remarks and Conclusions" section,
added one figure, added reference
Consciousness, Action Selection, Meaning and Phenomenic Anticipation
Phenomenal states are generally considered the ultimate sources of intrinsic motivation for autonomous biological agents. In this article, we will address the issue of the necessity of exploiting these states for the design and implementation of robust goal-directed artificial systems. We will provide an analysis of consciousness in terms of a precise definition of how an agent "understands" the informational flows entering the agent and its very own action possibilities. This abstract model of consciousness and understanding will be based in the analysis and evaluation of phenomenal states along potential future trajectories in the state space of the agents. This implies that a potential strategy to follow in order to build autonomous but still customer-useful systems is to embed them with the particular, ad hoc phenomenality that captures the system-external requirements that define the system usefulness from a customer-based, requirements-strict engineering viewpoint
Die reduktive ErklĂ€rbarkeit des phĂ€nomenalen Bewusstseins - C.D. Broad zur ErklĂ€rungslĂŒcke
Beckermann A. Die reduktive ErklĂ€rbarkeit des phĂ€nomenalen Bewusstseins - C.D. Broad zur ErklĂ€rungslĂŒcke. In: Pauen M, Stephan A, eds. PhĂ€nomenales BewuĂtsein - RĂŒckkehr zur IdentitĂ€tstheorie?. Paderborn: mentis; 2002: 122-147
12- to 14-month-olds expect unconstrained agents to act efficiently: Event-related potential (ERP) evidence from the head-touch paradigm
Behavioral research has shown that 12- but not 9-month-olds imitate an unusual and inefficient action (turning on a lamp with one's forehead) more when the model's hands are free. Rational-imitation accounts suggest that infants evaluate actions based on the rationality principle, that is, they expect people to choose efficient means to achieve a goal. Accordingly, infants' expectations should be violated when observing inefficient actions. However, this has yet to be clearly tested. Here, we conducted three electrophysiological experiments to assess infants' neural indices of violation of expectation (VOE) when observing hand- and head-touch actions. We presented infants with video sequences showing a model whose hands were either free (Experiments 1 and 3) or restrained (Experiment 2). Subsequent images depicted a person turning on a lamp or a toy soundbox using her hand or head. We analyzed the Negative central (Nc) component, associated with the amount of attentional engagement, and the N400 component, reflecting semantic violations. In line with rational-imitation accounts, results revealed that 12- to 14-month-olds (Experiment 1) but not 9-month-olds (Experiment 3) were surprised while observing an inefficient, hands-free, head touch, as indicated by an increased Nc amplitude and an N400-like component. In contrast, infants did not show differences in our measures of VOE between head- and hand-touch outcomes when the model's hands were restrained (Experiment 2). Thus, we suggest that 12- to 14-month-olds incorporate the action context when evaluating action outcomes
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