Feeling ready: neural bases of prospective motor readiness judgements

Under pressure in the Eriksen flanker task

A classical observation in experimental psychology is a reduction in reaction time and response accuracy under time pressure (TP). This speed-accuracy tradeoff may be understood from the combined perspectives of affordance competition and urgency gating. This view implies that action programs compete with each other from stimulus onset until the final response. Furthermore, responses are thought to be determined not just by the outcome of this competition but also by the urgency to respond. The latter aspect may play an important role in the case of speed stress. An experiment was conducted employing the Eriksen flanker task with different levels of TP. Behavioral, electromyographic (EMG), and electroencephalographic (EEG) data were registered. In the EEG analysis, source-level time-frequency activity was isolated for three sources (occipito-temporal, motor, and medial-frontal cortex). Inter-source phase coherence was computed to assess the neural dynamics underlying the effects of TP and flanker congruency. The EEG and EMG data revealed that TP affects visuo-motor links and motoric processes, while the flanker congruency effect was present from a very early level up to the final response. The present findings fit well within the combined perspectives of affordance competition and urgency gating.

Partial awareness during voluntary endogenous decision

Despite our feeling of control over decisions, our ability to consciously access choices before execution remains debated. Recent research reveals prospective access to intention to act, allowing potential vetoes of impending decisions. However, whether the content of impending decision can be accessed remain debated. Here we track neural signals during participants' early deliberation in free decisions. Participants chose freely between two options but sometimes had to reject their current decision just before execution. The initially preferred option, tracked in real time, significantly predicts the upcoming choice, but remain mostly outside of conscious awareness. Participants often display overconfidence in their access to this content. Instead, confidence is associated with a neural marker of self-initiated decision, indicating a qualitative confusion in the confidence evaluation process. Our results challenge the notion of complete agency over choices, suggesting inflated awareness of forthcoming decisions and providing insights into metacognitive processes in free decision-making.

Libet's legacy: A primer to the neuroscience of volition

The neuroscience of volition is an emerging subfield of the brain sciences, with hundreds of papers on the role of consciousness in action formation published each year. This makes the state-of-the-art in the discipline poorly accessible to newcomers and difficult to follow even for experts in the field. Here we provide a comprehensive summary of research in this field since its inception that will be useful to both groups. We also discuss important ideas that have received little coverage in the literature so far. We systematically reviewed a set of 2220 publications, with detailed consideration of almost 500 of the most relevant papers. We provide a thorough introduction to the seminal work of Benjamin Libet from the 1960s to 1980s. We also discuss common criticisms of Libet's method, including temporal introspection, the interpretation of the assumed physiological correlates of volition, and various conceptual issues. We conclude with recent advances and potential future directions in the field, highlighting modern methodological approaches to volition, as well as important recent findings.