Enhanced discriminability for nonbiological motion violating the two-thirds power law.

The two-thirds power law describes the relationship between velocity and curvature in human motor movements. Interestingly, this motor law also affects visual motion perception, in which stimuli moving according to the two-thirds power law are perceived to have a constant velocity compared to stimuli actually moving at constant velocity. Thus, visual motion adhering to biological motion principles causes a kinematic illusion of smooth and velocity-invariant motion. However, it is yet unclear how this motion law affects the discrimination of visual stimuli and if its encoding requires attention. Here we tested the perceptual discrimination of stimuli following biological (two-thirds power law) or nonbiological movement under conditions in which the stimuli were degraded or masked through continuous flash suppression. Additionally, we tested subjective perception of naturalness and velocity consistency. Our results show that the discriminability of a visual target is inversely related to the perceived "naturalness" of its movement. Discrimination of stimuli following the two-thirds power law required more time than the same stimuli moving at constant velocity or nonecological variants of the two-thirds power law and was present for both masked and degraded stimuli.

Comparing self- and hetero-metacognition in the absence of verbal communication.

The ability to infer how confident other people are in their decisions is crucial for regulating social interactions. In many cooperative situations, verbal communication enables one to communicate one's confidence and to appraise that of others. However, in many circumstances, people either cannot explicitly communicate their confidence level (e.g., in an emergency situation) or may be intentionally deceitful (e.g., when playing poker). It is currently unclear whether one can read others' confidence in the absence of verbal communication, and whether one can infer it as accurately as for one's own confidence. To explore these questions, we used an auditory task in which participants either had to guess the confidence of someone else performing the task or to judge their own confidence, in different conditions (i.e., while performing the task themselves or while watching themselves perform the task on a pre-recorded video). Results demonstrate that people can read the confidence someone else has in their decision as accurately as they evaluate their own uncertainty in their decision. Crucially, we show that hetero-metacognition is a flexible mechanism that relies on different cues according to the context. Our results support the idea that metacognition leverages the same inference mechanisms as those involved in theory of mind.

Sensorimotor conflicts alter metacognitive and action monitoring.

While sensorimotor signals are known to modulate perception, little is known about their influence on higher-level cognitive processes. Here, we applied sensorimotor conflicts while participants performed a perceptual task followed by confidence judgments. Results showed that sensorimotor conflicts altered metacognitive monitoring by decreasing metacognitive performance. In a second experiment, we replicated this finding and extended our results by showing that sensorimotor conflicts also altered action monitoring, as measured implicitly through intentional binding. In a third experiment, we replicated the same effects on intentional binding with sensorimotor conflicts related to the hand rather than to the trunk. However, effects of hand sensorimotor conflicts on metacognitive monitoring were not significant. Taken together, our results suggest that metacognitive and action monitoring may involve endogenous, embodied processes involving sensorimotor signals which are informative regarding the state of the decider.

Learning to Be Conscious.

Consciousness remains a formidable challenge. Different theories of consciousness have proposed vastly different mechanisms to account for phenomenal experience. Here, appealing to aspects of global workspace theory, higher-order theories, social theories, and predictive processing, we introduce a novel framework: the self-organizing metarerpresentational account (SOMA), in which consciousness is viewed as something that the brain learns to do. By this account, the brain continuously and unconsciously learns to redescribe its own activity to itself, so developing systems of metarepresentations that qualify target first-order representations. Thus, experiences only occur in experiencers that have learned to know they possess certain first-order states and that have learned to care more about certain states than about others. In this sense, consciousness is the brain's (unconscious, embodied, enactive, nonconceptual) theory about itself.

Waving goodbye to contrast: self-generated hand movements attenuate visual sensitivity.

It is well known that the human brain continuously predicts the sensory consequences of its own body movements, which typically results in sensory attenuation. Yet, the extent and exact mechanisms underlying sensory attenuation are still debated. To explore this issue, we asked participants to decide which of two visual stimuli was of higher contrast in a virtual reality situation where one of the stimuli could appear behind the participants' invisible moving hand or not. Over two experiments, we measured the effects of such "virtual occlusion" on first-order sensitivity and on metacognitive monitoring. Our findings show that self-generated hand movements reduced the apparent contrast of the stimulus. This result can be explained by the active inference theory. Moreover, sensory attenuation seemed to affect only first-order sensitivity and not (second-order) metacognitive judgments of confidence.

The Influence of (Dis)belief in Free Will on Immoral Behavior.

One of the hallmarks of human existence is that we all hold beliefs that determine how we act. Amongst such beliefs, the idea that we are endowed with free will appears to be linked to prosocial behaviors, probably by enhancing the feeling of responsibility of individuals over their own actions. However, such effects appear to be more complex that one might have initially thought. Here, we aimed at exploring how induced disbeliefs in free will impact the sense of agency over the consequences of one's own actions in a paradigm that engages morality. To do so, we asked participants to choose to inflict or to refrain from inflicting an electric choc to another participant in exchange of a small financial benefit. Our results show that participants who were primed with a text defending neural determinism - the idea that humans are a mere bunch of neurons guided by their biology - administered fewer shocks and were less vindictive toward the other participant. Importantly, this finding only held for female participants. These results show the complex interaction between gender, (dis)beliefs in free will and moral behavior.

Numerical Priming Between Touch and Vision Depends on Tactile Discrimination.

Although the interaction between vision and touch is of crucial importance for perceptual and bodily self-consciousness, only little is known regarding the link between conscious access and tactile processing. Here, we tested whether the numerical encoding of tactile stimuli depends on conscious discrimination. On each trial, participants received between zero and three taps at low, medium, or high intensity and had to enumerate the number of visual items subsequently presented as a visual target. We measured tactovisual numerical priming, that is, the modulation of reaction times according to the numerical distance between the visual target and tactile prime values. While numerical priming and repetition priming were respectively elicited by high and medium intensity stimuli, no effect was found for low intensity stimuli that were not discriminable. This suggests that numerical priming between touch and vision depends on tactile discrimination. We discuss our results considering recent advances in unconscious visual numerical priming.