Impaired perception of a partner's synchronizing behavior reduces positive attitude toward humanoid robot in schizophrenia patients.

As interpersonal synchrony plays a key role in building rapport, the perception of another agent's synchronizing behavior could be an important feature to assess, especially with patients with social deficits such as in schizophrenia. Twenty-four schizophrenia patients and twenty-four matched healthy controls performed jointly fitness movements with another agent embodied by a humanoid robot which was programmed to either synchronize with the participants or move at a fixed frequency with them. Self-report of participants' perception of the robot's synchronizing behavior was collected after each interaction. Results indicated that patients were impaired in their ability to accurately perceive the robot's synchronizing behavior. Patients' subjective perception of the robot's synchronizing behavior was associated with positive attitude toward it, suggesting that the belief to be synchronized with others could have similar impact on affiliation than real interpersonal synchrony. It leads to new perspectives for understanding social deficits in people with severe mental illness.

Leg movements affect speech intensity.

Coordination between speech acoustics and manual gestures has been conceived as "not biologically mandated" (McClave E. J Psycholinguist Res 27(1): 69-89, 1998). However, recent work suggests a biomechanical entanglement between the upper limbs and the respiratory-vocal system (Pouw W, de Jonge-Hoekstra D, Harrison SJ, Paxton A, Dixon JA. Ann NY Acad Sci 1491(1): 89-105, 2021). Pouw et al. found that for movements with a high physical impulse, speech acoustics co-occur with the physical impulses of upper limb movements. They interpret this result in terms of biomechanical coupling between arm motion and speech via the breathing system. This coupling could support the synchrony observed between speech prosody and arm gestures during communication. The present study investigates whether the effect of physical impulse on speech acoustics can be extended to leg motion, assumed to be controlled independently from oral communication. The study involved 25 native speakers of German who recalled short stories while biking with their arms or their legs. These conditions were compared with a static condition in which participants could not move their arms. Our analyses are similar to that of Pouw et al. (Pouw W, de Jonge-Hoekstra D, Harrison SJ, Paxton A, Dixon JA. Ann NY Acad Sci 1491(1): 89-105, 2021). Results reveal that the presence of intensity peaks in the acoustic signal co-occur with the time of peak acceleration of legs' biking movements. However, this was not observed when biking with the arms, which corresponded to lower acceleration peaks. In contrast to intensity, F0 was not affected in the arm and leg conditions. These results suggest that 1) the biomechanical entanglements between the respiratory-vocal system and the lower limbs may also impact speech; 2) the physical impulse may have to reach a threshold to impact speech acoustics.NEW & NOTEWORTHY The link between speech and limb motion is an interdisciplinary challenge and a core issue in motor control and language research. Our research aims to disentangle the potential biomechanical links between lower limbs and the speech apparatus, by investigating the effect of leg movements on speech acoustics.

Effects of unintentional coordination on attentional load.

The goal of this study was to evaluate the impact of unintentional (spontaneous) coordination on high attentional visual load. More precisely, we wondered whether such coordination could free up some attentional resources and help improve performance in other more demanding attentional tasks. An experiment was performed in which participant attentional allocation was challenged by performing three tasks simultaneously while simultaneously being induced to unintentional entrain to an environmental rhythm. The first task was an interception task associated with a Stroop test to increase their attentional load. The second task was a reaction time test to alarms in different modalities (auditory, visual and bimodal) which was used to assess participant attentional load. The third task was a motor task in which participants were asked to swing their legs at a preferred frequency. The interface background brightness intensity was either synchronized in real time using a bidirectional coupling to participant leg movement or the background brightness was not changing at all. Our results on the reaction time task demonstrated that participants exhibited better reaction times for alarms in the bimodal condition than in the auditory condition and lastly for the visual condition. Also, participants exhibited a lower reaction time to alarms when the background brightness was synchronizing with their leg regardless the alarm modality. Overall, our study suggests a beneficial effect of unintentional environmental coordination on attentional resource allocation and highlights the importance of bidirectionality in interaction.

Speech breathing: variable but individual over time and according to limb movements.

Breathing is variable but also highly individual. Since the 1980s, evidence of a ventilatory personality has been observed in different physiological studies. This original term refers to within-speaker consistency in breathing characteristics across days or even years. Speech breathing is a specific way to control ventilation while supporting speech planning and phonation constraints. It is highly variable between speakers but also for the same speaker, depending on utterance properties, bodily actions, and the context of an interaction. Can we yet still observe consistency over time in speakers' breathing profiles despite these variations? We addressed this question by analyzing the breathing profiles of 25 native speakers of German performing a narrative task on 2 days under different limb movement conditions. The individuality of breathing profiles over conditions and days was assessed by adopting methods used in physiological studies that investigated a ventilatory personality. Our results suggest that speaker-specific breathing profiles in a narrative task are maintained over days and that they stay consistent despite light physical activity. These results are discussed with a focus on better understanding what speech breathing individuality is, how it can be assessed, and the types of research perspectives that this concept opens up.