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Abstracts
  • Meissner, K., & Wittmann, M. (2011). Body signals, cardiac awareness, and the perception of time. Biological Psychology, 86(3), 289–297. https://doi.org/10.1016/j.biopsycho.2011.01.001

    Recent research suggests that our sense of time intervals in the range of seconds is directly related to activity in the insular cortex, which contains the primary sensory area for interoception. We therefore investigated whether performance in a duration reproduction task might correlate with individual interoceptive awareness and with measurable changes in autonomic activity during the task. Thirty-one healthy volunteers participated in an interoceptive (heartbeat) perception task and in repeated temporal reproduction trials using intervals of 8, 14, and 20s duration while skin conductance levels and cardiac and respiratory periods were recorded. We observed progressive increases in cardiac periods and decreases in skin conductance level during the encoding and (less reliably) the reproduction of these intervals. Notably, individuals' duration reproduction accuracy correlated positively both with the slope of cardiac slowing during the encoding intervals and with individual heartbeat perception scores. These results support the view that autonomic function and interoceptive awareness underpin our perception of time intervals in the range of seconds.

  • Jo, H.-G., Hinterberger, T., Wittmann, M., & Schmidt, S. (2015). Do meditators have higher awareness of their intentions to act? Cortex; a Journal Devoted to the Study of the Nervous System and Behavior, 65, 149–158. https://doi.org/10.1016/j.cortex.2014.12.015

    Intuitively, being aware of one's inner processes to move should be crucial for the control of voluntary movements. However, research findings suggest that we are not always aware of the processes leading to movement execution. The present study investigated induced first-person access to inner processes of movement initiation and the underlying brain activities which contribute to the emergence of voluntary movement. Moreover, we investigated differences in task performance between mindfulness meditators and non-meditators while assuming that meditators are more experienced in attending to their inner processes. Two Libet-type tasks were performed; one in which participants were asked to press a button at a moment of their own decision, and the other one in which participants' attention was directed towards their inner processes of decision making regarding the intended movement which lead them to press the button. Meditators revealed a consistent readiness potential (RP) between the two tasks with correlations between the subjective intention time to act and the slope of the early RP. However, non-meditators did not show this consistency. Instead, elicited introspection of inner processes of movement initiation changed early brain activity that is related to voluntary movement processes. Our findings suggest that compared to non-meditators, meditators are more able to access the emergence of negative deflections of slow cortical potentials (SCPs), which could have fundamental effects on initiating a voluntary movement with awareness.

  • Schmidt, S., Jo, H.-G., Wittmann, M., & Hinterberger, T. (2016). “Catching the waves” - slow cortical potentials as moderator of voluntary action. Neuroscience and Biobehavioral Reviews, 68, 639–650. https://doi.org/10.1016/j.neubiorev.2016.06.023

    The readiness potential is an ongoing negativity in the EEG preceding a self-initiated movement by approximately 1.5s. So far it has predominantly been interpreted as a preparatory signal with a causal link to the upcoming movement. Here a different hypothesis is suggested which we call the selective slow cortical potential sampling hypothesis. In this review of recent research results we argue that the initiation of a voluntary action is more likely during negative fluctuations of the slow cortical potential and that the sampling and averaging of many trials leads to the observed negativity. That is, empirical evidence indicates that the early readiness potential is not a neural correlate of preconscious motor preparation and thus a determinant of action. Our hypothesis thereafter challenges the classic interpretation of the Libet experiment which is often taken as proof that there is no free will. We furthermore suggest that slow cortical potentials are related to an urge to act but are not a neural indicator of the decision process of action initiation.

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Last update from database: 11.08.25, 05:41 (UTC)