Conversational Alignment: A Study of Neural Coherence and Speech Entrainment

Conversational alignment refers to the tendency for communication partners to adjust their verbal and non-verbal behaviors to become more like one another during the course of human interaction. This alignment phenomenon has been observed in neural patterns, specifically in the prefrontal areas of the brain (Holper et al., 2013; Cui et al., 2012; Dommer et al., 2012; Holper et al., 2012; Funane et al., 2011; Jiang et al., 2012); verbal behaviors such acoustic speech features (e.g., Borrie & Liss, 2014; Borrie et al., 2015; Lubold & Pon-Barry, 2014), phonological features (e.g., Babel, 2012; Pardo, 2006), lexical selection (e.g., Brennan & Clark, 1996; Garrod & Anderson, 1989), syntactic structure (e.g., Branigan, Pickering, & Cleland, 2000; Reitter, Moore, & Keller, 2006); and motor behaviors including body posture, facial expressions and breathing rate (e.g., Furuyama, Hayashi, & Mishima, 2005; Louwerse, Dale, Bard, & Jeuniaux, 2012; Richardson, March, & Schmit, 2005; Shockley, Santana, & Fowler, 2003; McFarland, 2001). While conversational alignment in itself, is a largely physical phenomenon, it has been linked to significant functional value, both in the cognitive and social domains. Cognitively, conversational alignment facilitates spoken message comprehension, enabling listeners to share mental models (Garrod & Pickering, 2004) and generate temporal predictions about upcoming aspects of speech. From a social perspective, behavioral alignment has been linked with establishing turn-taking behaviors, and with increased feelings of rapport, empathy, and intimacy between conversational pairs (e.g., Lee et al. 2010; Nind, & Macrae, 2009; Smith, 2008; Bailenson & Yee, 2005; Chartrand & Barg, 1999; Miles, Putman & Street, 1984; Street & Giles, 1982). Benus (2014), for example, observed that individuals who align their speech features are perceived as more socially attractive and likeable, and have interactions that are more successful. These cognitive and social benefits, associated with conversational alignment, have been observed in both linguistic and neural data (e.g., Holper et al., 2012; 2013, Cui et al. 2012; Jiang et al., 2012; Egetemeir et al., 2011; Stephens et al. 2010). The purpose of the current study was to examine conversational alignment as a multi-level communication phenomenon, by examining the relationship between neural and speech behaviors. To assess neural alignment, we used Near-Infrared Spectroscopy (NIRS), a non-invasive neuroimaging technology that detects cortical increases and decreases in the concentration of oxygenated and deoxygenated hemoglobin at multiple measurement sites to determine the rate that oxygen is being released and absorbed (Ferrari & Quaresima, 2012). While still considered a relatively new neural imaging technique, NIRS has been well established as an efficacious and effective data collection approach, particularly appropriate for social interaction research (e.g., Holper et al., 2013; Jiang et al., 2012; Holper et al., 2012; Suda et al., 2010). We utilized hyperscanning, a technique that allows for the quantitation of two simultaneous signals, allowing us to document neural alignment between two individuals (Babiloni & Astolfi, 2012). Recent studies have revealed neural alignment between two persons in cooperative states, including alignment in the right superior frontal cortices and medial prefrontal regions (Cui et al., 2012; Dommer et al., 2012; Funane et al., 2011). This increased prefrontal interbrain alignment has also been observed in other social interactions, including joint attention tasks (Dommer et al., 2012), imitation tasks (Holper et al., 2012), competitive games (Cheng et al., 2015, Duan et al., 2013), teaching-learning interactions (Holper et al., 2013), face- to-face communication (Jiang et al., 2012), mother-child interactions (Hirata et al., 2014), and during cooperative singing tasks (Osaka et al., 2015). Interestingly, Jiang et al. (2012) showed that increased neural alignment only occurred between conversational participants when they were speaking face-to-face, but not when participants had their backs facing one another. The authors speculated that the multi-sensory information, for example motor behaviors such as gestures, was required for neural alignment to occur

Brains in Competition: Improved Cognitive Performance and Inter-Brain Coupling by Hyperscanning Paradigm with Functional Near-Infrared Spectroscopy

Hyperscanning brain paradigm was applied to competitive task for couples of subjects. Functional Near-Infrared Spectroscopy (fNIRS) and cognitive performance were considered to test inter-brain and cognitive strategy similarities between subjects (14 couples) during a joint-action. We supposed increased brain-to-brain coupling and improved cognitive outcomes due to joint-action and the competition. As supposed, the direct interaction between the subjects and the observed external feedback of their performance (an experimentally induced fictitious feedback) affected the cognitive performance with decreased Error Rates (ERs), and Response Times (RTs). In addition, fNIRS measure (oxyhemoglobin, O2Hb) revealed an increased brain activity in the prefrontal cortex (PFC) in post-feedback more than pre-feedback condition. Moreover, a higher inter-brain similarity was found for the couples during the task, with higher matched brain response in post-feedback condition than pre-feedback. Finally, a significant increased prefrontal brain lateralization effect was observed for the right hemisphere. Indeed the right PFC was more responsive with similar modalities within the couple during the post-feedback condition. The joined-task and competitive context was adduced to explain these cognitive performance improving, synergic brain responsiveness within the couples and lateralization effects (negative emotions)

Two is better than one: The effects of strategic cooperation on intra- and inter-brain connectivity by fNIRS

Inter-brain synchronization during joint actions is a core question in social neuroscience, and the differential contribution of intra- and inter-brain functional connectivity has yet to be clarified along with the role of psychological variables such as perceived self-efficacy. The cognitive performance and the neural activation underlying the execution of joint actions were recorded by functional Near-Infrared imaging during a synchronicity game. An 8-channel array of optodes was positioned over the frontal and prefrontal regions. During the task, the dyads received reinforcing feedback that was experimentally manipulated to induce adoption of common strategies. Intra- and inter-brain connectivity indices were computed along with an inter-brain/intra-brain connectivity index (ConIndex). Finally, correlation analyses were run to assess the relationship between behavioral and physiological levels. The results showed that the external feedback could modulate participant responses in both behavioral and neural components. After the reinforcing manipulation, there were faster response times and increased inter-brain connectivity, and ConIndex emerged primarily over the dorsolateral prefrontal cortex. Additionally, the presence of significant correlations between response times and inter-brain connectivity revealed that only the \ue2\u80\u9ctwo-players connection\ue2\u80\u9d may guarantee an efficient performance. The present study provides a significant contribution to the identification of intra- and inter-brain functional connectivity when social reinforcement is provided

Frontal alpha oscillations distinguish leaders from followers: Multivariate decoding of mutually interacting brains

Successful social interactions rely upon the abilities of two or more people to mutually exchange information in real-time, while simultaneously adapting to one another. The neural basis of social cognition has mostly been investigated in isolated individuals, and more recently using two-person paradigms to quantify the neuronal dynamics underlying social interaction. While several studies have shown the relevance of understanding complementary and mutually adaptive processes, the neural mechanisms underlying such coordinative behavioral patterns during joint action remain largely unknown. Here, we employed a synchronized finger-tapping task while measuring dual-EEG from pairs of human participants who either mutually adjusted to each other in an interactive task or followed a computer metronome. Neurophysiologically, the interactive condition was characterized by a stronger suppression of alpha and low-beta oscillations over motor and frontal areas in contrast to the non-interactive computer condition. A multivariate analysis of two-brain activity to classify interactive versus non-interactive trials revealed asymmetric patterns of the frontal alpha-suppression in each pair, during both task anticipation and execution, such that only one member showed the frontal component. Analysis of the behavioral data showed that this distinction coincided with the leader–follower relationship in 8/9 pairs, with the leaders characterized by the stronger frontal alpha-suppression. This suggests that leaders invest more resources in prospective planning and control. Hence our results show that the spontaneous emergence of leader–follower relationships in dyadic interactions can be predicted from EEG recordings of brain activity prior to and during interaction. Furthermore, this emphasizes the importance of investigating complementarity in joint action

Brains in Competition : Improved Cognitive Performance and Inter-Brain Coupling by Hyperscanning Paradigm with Functional Near-Infrared Spectroscopy

Hyperscanning brain paradigm was applied to competitive task for couples of subjects. Functional Near-Infrared Spectroscopy (fNIRS) and cognitive performance were considered to test inter-brain and cognitive strategy similarities between subjects (14 couples) during a joint-action. We supposed increased brain-to-brain coupling and improved cognitive outcomes due to joint-action and the competition. As supposed, the direct interaction between the subjects and the observed external feedback of their performance (an experimentally induced fictitious feedback) affected the cognitive performance with decreased Error Rates (ERs), and Response Times (RTs). In addition, fNIRS measure (oxyhemoglobin, O2Hb) revealed an increased brain activity in the prefrontal cortex (PFC) in post-feedback more than pre-feedback condition. Moreover, a higher inter-brain similarity was found for the couples during the task, with higher matched brain response in post-feedback condition than pre-feedback. Finally, a significant increased prefrontal brain lateralization effect was observed for the right hemisphere. Indeed the right PFC was more responsive with similar modalities within the couple during the post-feedback condition. The joined-task and competitive context was adduced to explain these cognitive performance improving, synergic brain responsiveness within the couples and lateralization effects (negative emotions)

Functional EEG connectivity during competition

Social behavior and interactions pervasively shape and influence our lives and relationships. Competition, in particular, has become a core topic in social neuroscience since it stresses the relevance and salience of social comparison processes between the inter-agents that are involved in a common task. The majority of studies, however, investigated such kind of social interaction via one-person individual paradigms, thus not taking into account relevant information concerning interdependent participants' behavioral and neural responses. In the present study, dyads of volunteers participated in a hyperscanning paradigm and competed in a computerized attention task while their electrophysiological (EEG) activity and performance were monitored and recorded. Behavioral data and inter-brain coupling measures based on EEG frequency data were then computed and compared across different experimental conditions: a control condition (individual task, t0), a first competitive condition (pre-feedback condition, t1), and a second competitive condition following a positive reinforcing feedback (post-feedback condition, t2)

Lateralization difference in functional activity during Stroop tasks: a functional near-infrared spectroscopy and EEG simultaneous study

IntroductionConflict monitoring and processing is an important part of the human cognitive system, it plays a key role in many studies of cognitive disorders.MethodsBased on a Chinese word-color match Stroop task, which included incongruent and neutral stimuli, the Electroencephalogram (EEG) and functional Near-infrared Spectroscopy (fNIRS) signals were recorded simultaneously. The Pearson correlation coefficient matrix was calculated to analyze brain connectivity based on EEG signals. Granger Causality (GC) method was employed to analyze the effective connectivity of bilateral frontal lobes. Wavelet Transform Coherence (WTC) was used to analyze the functional connectivity of the bilateral hemisphere and ipsilateral hemisphere.ResultsResults indicated that brain connectivity analysis on EEG signals did not show any significant lateralization, while fNIRS analysis results showed the frontal lobes especially the left frontal lobe play the leading role in dealing with conflict tasks. The human brain shows leftward lateralization while processing the more complicated incongruent stimuli. This is demonstrated by the higher functional connectivity in the left frontal lobe and the information flow from the left frontal lobe to the right frontal lobe.DiscussionOur findings in brain connectivity during cognitive conflict processing demonstrated that the dual modality method combining EEG and fNIRS is a valuable tool to excavate more information through cognitive and physiological studies

Two is better than one : the effects of strategic cooperation on intra- and inter-brain connectivity by fNIRS

Inter-brain synchronization during joint actions is a core question in social neuroscience, and the differential contribution of intra- and inter-brain functional connectivity has yet to be clarified along with the role of psychological variables such as perceived self-efficacy. The cognitive performance and the neural activation underlying the execution of joint actions were recorded by functional Near-Infrared imaging during a synchronicity game. An 8-channel array of optodes was positioned over the frontal and prefrontal regions. During the task, the dyads received reinforcing feedback that was experimentally manipulated to induce adoption of common strategies. Intra- and inter-brain connectivity indices were computed along with an inter-brain/intra-brain connectivity index (ConIndex). Finally, correlation analyses were run to assess the relationship between behavioral and physiological levels. The results showed that the external feedback could modulate participant responses in both behavioral and neural components. After the reinforcing manipulation, there were faster response times and increased inter-brain connectivity, and ConIndex emerged primarily over the dorsolateral prefrontal cortex. Additionally, the presence of significant correlations between response times and inter-brain connectivity revealed that only the \u201ctwo-players connection\u201d may guarantee an efficient performance. The present study provides a significant contribution to the identification of intra- and inter-brain functional connectivity when social reinforcement is provided

EEG hyperscanning and behavioral synchronization during a joint actions

Brain-to-brain coupling during cooperation is a core question of study on social interactions. The aim of the present study was to investigate the neural basis of interbrain cooperation and the cognitive performance underlying the execution of jointactions by using EEG coherence measures. Synchronicity of the cognitive variables (response times, RTs, and error rates, ERs) in response to an attentional task, intersubjective coherence analysis on EEG frequency bands, and correlational measures between cognitive and brain activity were considered during some steps of progressive reinforcing conditions. Fifteen couples of subjects performed an attentional task in eight temporal steps, stressing their good performance at the end of each step. The induced feedback affected both the cognitive performance and brain-to-brain coupling by increasing behavioral and brain synchronization when a positive feedback was furnished to the participants for their performance. Secondly, about the cortical contribution, high coherence effect was mainly observed when a positive reinforce was produced, but only for some low frequency bands within the prefrontal left area, compared to the right one. Thus, also a left lateralization effect was reportable. Finally, the cognitive and EEG coherence measures were shown to be correlated, with a significant similar trend anchored to the progressive feedback

When cooperation goes wrong : brain and behavioural correlates of ineffective joint strategies in dyads

Purpose: Human life is connoted by sophisticated interactions that involve not only single individuals, but larger social groups composed by members interacting each other. Cooperation secures a benefit to all the people engaged as well as important behaviors like helping, sharing, and acting prosocially. But what happens when the joint actions are not effective? Materials and method: In the present study, we asked 24 participants paired in 12 dyads to cooperate during an attentional task in a way to synchronize their responses and obtain better outcomes. In addition we tested inter-brain and cognitive strategy similarities between subjects. Then, we frustrated their strategies by providing false feedbacks signalling the incapacity to create a synergy, which was reinforced by a general negative evaluation halfway through the task. The effects of the feedback inmodulating subjects behavioural performance and brain responsiveness were explored by means of functional near-infrared spectroscopy (fNIRS). Results: Results showed a worsen performance after the negative feedback in the form of longer reaction times and a specifc pattern of brain activation involving th dorsolateral prefrontal cortex (DLPFC) and the superior frontal gyrus. The DLPFC showed increased O2Hb (oxy-haemoglobin) level after the feedback, compatible with the need for higher cognitive effort. In addition, fNIRS measures revealed a decreased inter-brain synchronicity in post-feedback condition for the dyad. Also, the representation of negative emotions in response to failing interactions was signalled by a right-lateralized effect. Conclusions: Results were interpreted at light of available knowledge on perceived self-efficacy and the implementation of common goals and strategies