Mathieu Gueugnon

The acquisition of socio-motor improvisation in the mirror game

Socio-motor improvisation is defined as the creative action of two or more people without a script or anticipated preparation. It is evaluated through two main parameters: movement synchronization and movement richness. Experts in art (e.g., dance, theater or music) are known to exhibit higher synchronization and to perform richer movements during interpersonal improvisation, but how these competences evolve over time is largely unknown. In the present study, we investigated whether performing more synchronized and richer movements over time can promote the acquisition of improvisation. Pairs of novice participants were instructed to play an improvisation mirror game in three different sessions. Between sessions, they performed an unintended interpersonal coordination task in which synchronization and richness were manipulated, resulting in four different groups of dyads. Our results demonstrate that synchronization during improvisation improved for all groups whereas movement richness only enhanced for dyads that performed synchronized movements during unintended coordination tasks. Our findings suggest that movement synchrony contributes more than movement richness to the acquisition of socio-motor improvisation in the mirror game.

Unravelling socio-motor biomarkers in schizophrenia

We present novel, low-cost and non-invasive potential diagnostic biomarkers of schizophrenia. They are based on the ‘mirror-game’, a coordination task in which two partners are asked to mimic each other’s hand movements. In particular, we use the patient’s solo movement, recorded in the absence of a partner, and motion recorded during interaction with an artificial agent, a computer avatar or a humanoid robot. In order to discriminate between the patients and controls, we employ statistical learning techniques, which we apply to nonverbal synchrony and neuromotor features derived from the participants’ movement data. The proposed classifier has 93% accuracy and 100% specificity. Our results provide evidence that statistical learning techniques, nonverbal movement coordination and neuromotor characteristics could form the foundation of decision support tools aiding clinicians in cases of diagnostic uncertainty.Mirror game test could detect schizophreniaA new test of movement and social interaction could detect markers of schizophrenia, and help to diagnose and manage the condition. In an effort to establish reliable indicators of schizophrenia, Piotr Slowinski at the University of Exeter, UK and colleagues developed a test that could detect deficits in movement and social interactions, both characteristics of the disorder. They asked people to perform movements alone, and to mirror the movements of a computer avatar or a humanoid robot. Automated analysis of the movements allowed to distinguish people with schizophrenia from healthy participants with accuracy and specificity slightly better than clinical interviews and comparable to test based on much more expensive neuroimaging methods. The technique could help with diagnosis of schizophrenia and to monitor patients’ responses to treatment, but needs to be tested in clinical trials before being applied in clincal practice.

Asymmetries of bilateral isometric force matching with movement intention and unilateral fatigue

AbstractDuring bilateral coordination, some level of inter-hemispheric remapping (i.e., the congruency between afferent and efferent force signals from both hemispheres) is required. In this case, sensory-motor information is exchanged between the two hemispheres, but it remains unclear whether this information exchange is always equivalent or not, especially in a bilateral isometric force-matching task. We used unilateral fatigue applied to one arm in order to determine whether inter-hemispheric remapping can vary asymmetrically during a bilateral isometric matching task. Because fatigue is considered to bias the sensory-motor system, we hypothesized that if bimanual coordination is modulated solely in function of the state of the sensory-motor system (motor efferences, inter-hemispheric inhibitions, and sensory reafferences), we should not observe any asymmetric effect of fatigue with movement intention (leading vs. matching arm). However, if any other process could participate in the modulation of inter-hemispheric remapping, we should observe an interaction between movement intentions and fatigue on the force produced. We found that, when the leading arm was the non-fatigued arm, participants succeeded in reproducing the force level with their fatigued arm. By contrast, when the leading arm was fatigued, subjects over-estimated the force level produced with their non-fatigued arm. Hence, lateralized fatigue exacerbates an asymmetric behavior that seems modulated by movement intention (leading vs. matching). In other words, when unilateral fatigue is introduced in a bilateral isometric force-matching task, inter-hemispheric remapping is asymmetrical. Intensity levels of motor commands sent to both arms (directly or modulated through inter-hemispheric inhibitions) and sensory reafferences alone cannot explain these observations. Some attentional focus may be not balanced continuously between both arms but may be mainly directed toward the matching arm.

Postural Coordination during Socio-motor Improvisation

Human interaction often relies on socio-motor improvisation. Creating unprepared movements during social interaction is not a random process but relies on rules of synchronization. These situations do not only involve people to be coordinated, but also require the adjustment of their posture in order to maintain balance and support movements. The present study investigated posture in such a context. More precisely, we first evaluated the impact of amplitude and complexity of arm movements on posture in solo situation. Then, we assessed the impact of interpersonal coordination on posture using the mirror game in which dyads performed improvised and synchronized movements (i.e., duo situation). Posture was measured through ankle-hip coordination in medio-lateral and antero-posterior directions (ML and AP respectively). Our results revealed the spontaneous emergence of in-phase pattern in ML direction and antiphase pattern in AP direction for solo and duo situations. These two patterns respectively refer to the simultaneous flexion/extension of the ankles and the hips in the same or opposite direction. It suggests different functional roles of postural coordination patterns in each direction, with in-phase supporting task performance in ML (dynamical stability) and antiphase supporting postural control in AP (mechanical stability). Although amplitude of movement did not influence posture, movement complexity disturbed postural stability in both directions. Conversely, interpersonal coordination promoted postural stability in ML but not in AP direction. These results are discussed in terms of the difference in coupling strength between ankle-hip coordination and interpersonal coordination.

Movement similarities and differences during social interaction: The scientific foundation of the ALTEREGO European project

Schizophrenia, autism, or social phobia are typically accompanied by social interaction deficits. The objective of the AlterEgo European project is the creation of an interactive cognitive architecture, implementable in various artificial agents, allowing a continuous interaction with patients suffering from social disorders by virtue of changes in behavioral (robot-based) as well as morphological (avatar-based) properties of that agent. Here we present the scientific foundations of the project and its four main experimental steps. The results of the first similarity experiments are reported, which show that healthy participants functionally adapt their social motor interaction when they interact with agents (real or artificial) morphologically and behaviorally similar to, or different from, them. These results obtained with healthy participants have consequences for the rehabilitation of socially deficient patients.

Standing or swaying to the beat: Discrete auditory rhythms entrain stance and promote postural coordination stability

Humans seem to take social and behavioral advantages of entraining themselves with discrete auditory rhythms (e.g., dancing, communicating). We investigated the benefits of such an entrainment on posture during standing (spontaneous entrainment) and during a whole-body swaying task (intentional synchronization). We first evaluated how body sway was entrained by different auditory metronome frequencies (0.25, 0.5, and 1.0Hz). We then assessed the stabilizing role of auditory rhythms on postural control, characterized in a dynamical systems perspective by informational anchoring of the head (local stabilization) and fewer transitions from in-phase to anti-phase ankle-hip coordination (global stabilization). Our results revealed in both situations an entrainment of postural movements by external rhythms. This entrainment tended to be more effective when the metronome frequency (0.25Hz) was close to the dominant sway frequency. Particularly, we found during intentional synchronization that head movements were less variable when paced by a slower beat (informational anchoring), and that phase transitions between the two stable patterns in postural dynamics were delayed. Our findings demonstrate that human bipedal posture can be actively or spontaneously modulated by an external discrete auditory rhythm, which might be exploited for the purpose of learning and rehabilitation.

Understanding the Impact of Expertise in Joint and Solo-Improvisation

Joint-improvisation is not only an open-ended creative action that two or more people perform together in the context of an artistic performance (e.g., theatre, music or dance). Joint-improvisation also takes place in daily life activities when humans take part in collective performance such as toddlers at play or adults engaged in a conversation. In the context of this article, joint-improvisation has been looked at from a social motor coordination perspective. In the literature, the nature of the social motor coordination characteristics of joint-improvisation for either the creative aspect or daily life features of this motor performance remains unclear. Additionally, both solo-improvisation and joint-improvisation need to be studied conjointly to establish the influence of the social element of improvisation in the emergence of multi-agent motor coordination. In order to better understand those two types of improvisation, we compared three level of expertise – novice, intermediate and professional in dance improvisation to identify movement characteristics for each of the groups. Pairs of the same level were asked to improvise together. Each individual was also asked to perform an improvisation on his/her own. We found that each of the three groups present specific movement organization with movement complexity increasing with the level of expertise. Experts performed shorter movement duration in conjunction with an increase range of movement. The direct comparison of individual and paired Conditions highlighted that the joint-improvisation reduced the complexity of the movement organization and those for all three levels while maintaining the differences between the groups. This direct comparison amongst those three distinct groups provides an original insight onto the nature of movement patterns in joint-improvisation situation. Overall, it reveals the role of both individual and collective properties in the emergence of social coordination.

Likability’s Effect on Interpersonal Motor Coordination: Exploring Natural Gaze Direction

Although existing studies indicate a positive effect of interpersonal motor coordination (IMC) on likability, no consensus has been reached as for the effect of likability back onto IMC. The present study specifically investigated the causal effect of likability on IMC and explored, by tracking the natural gaze direction, the possible underlying mechanisms. Twenty-two participants were engaged in an interpersonal finger-tapping task with a confederate in three likability conditions (baseline, likable, and unlikable), while wearing an eye tracker. They had to perform finger tapping at their comfort tempo with the confederate who tapped at the same or 1.5 times of the participant’s preferred frequency. Results showed that when tapping at the same frequency, the effect of likability on IMC varied with time. Participants coordinated at a higher level in the baseline condition at the beginning of the coordination task, and a facilitative effect of likability on IMC was revealed in the last session. As a novelty, our results evidenced a positive correlation between IMC and the amount of gaze onto the coordination partner’s movement only in the likable condition. No effect of likability was found when the confederate was tapping at 1.5 times of the participant’s preferred frequency. Our research suggests that the psychosocial property of the coordinating partner should be taken into consideration when investigating the performance of IMC and that IMC is a parameter that is sensitive to multiple factors.