Open research questions in Action Observation and Synchronization

What the literature leaves open

• , 2023) may be context-sensitive, a salient color-based context change is insufficient to completely abolish short-term action-effect associations.

  Short-term action-effect bindings encode perceptual transitions rather than perceptual end-states · 2026 · DOI

• Existing individual preparation (IP) research mainly relied on behavioral data and has rarely been examined with physiological evidence, leaving its underlying mechanisms largely unexplored.

  The role of individual preparation on coordination in computer-supported collaborative learning: a neuroscience perspective on learners’ inter-brain synchrony · 2026 · DOI

• However, little is known about the spatial code of tactile body memories, particularly whether encoding takes place in a body-centered (tactile) reference frame, not influenced by hand posture or visual cues, or whether it takes place in an external reference frame, where tactile information is integrated with proprioceptive and visual information.

  Body-centered encoding of passive tactile pattern memories · 2026 · DOI

• A limitation of this study may be associated with the time series analysis, which is also a distinctive feature of this study. In this study, the interpersonal coordination measures were carefully tailored to the theory (Bernieri & Rosenthal, 1991) with a reliable automated technique. The use of a measure that resembles an effect size using a surrogate distribution (Moulder et al., 2018; Tschacher et al., 2018) should also have reduced the influence of potential bias based on a limited number of random shuffles. Even after introducing these improvements, the results are consistent with previous studies (Mogan et al., 2017; Rennung & Göritz, 2016; Vicaria & Dickens, 2016). Still, it is also true that the results of time series analysis are sensitive to the parameter choices (Boker et al., 2002), and this study involves a variety of decisions regarding the analysis; for example, whether to downsample, detrend,3 and standardize time series, whether to interporate missing values, the method of smoothing and random shuffling, the frequency bands of synchrony to focus on, the range of time lags to consider. We followed prior research to ensure comparability for many of these, though not all aspects, such as the measure of behavior matching using joint angles, necessarily did so. Given the current development of this research field, we cannot and should not exclude the possibility that other analyses may reach different conclusions. No single paper would be conclusive on this point, and the presence or absence of statistical significance in a few selected papers should not be overstated. Rather, researchers in this field will be encouraged to make a collective effort to accumulate findings and develop an open discussion in the future. We created a single-vector movement time series from OpenPose outputs. This is because there seemed to be an advantage in maintaining consistency with previous studies that examined the coordination-rapport link using MEA (Fujiwara et al., 2021; Fujiwara et al., 2020). Also, since our primary focus was to simultaneously measure interactional synchrony and behavior matching (posture mirroring) using OpenPose output, and to examine their relationship with rapport, overly detailed analysis might unnecessarily complicate this research. However, this decision might have its pros and cons, as our study failed to pursue more detailed questions, such as which body part of synchrony particularly contributed to rapport building. The same applies to behavior matching; identifying the specific body parts primarily involved in behavioral matching had not been explored. While increasing the granularity 3 Long scale temporal patterns do not seem to influence on our measures of behavior matching (posture mirroring) and rhythm synchrony because we adopted a segment-wise approach to measure them.

  The Coordination-Rapport Link, Revisited: A Study with Automated Coding Techniques · 2026 · DOI

• and increases (Gilin et al., 2013). Beyond its neural grounding, empathy operates socially by shaping how novel deviations are interpreted and evaluated within collective contexts. Perspective taking—the capacity to adopt another person’s standpoint and infer their intentions—plays a particularly important role in this process. In negotiation of research, hidden agreements and enables the creation of joint value (Galinsky et al., 2008), while improving outcomes in mixed-motive situations intergroup social boundaries contact (Wang et al., 2014). From this perspective, perspective taking may transform exploratory deviations that are to others. When combined with interoceptive intelligible this process bodily allows creative mismatches to be socially interpreted rather than dismissed. In doing so, empathy and perspective taking help regulate the balance between exploratory creativity and to incorporate ethical acceptability, enabling social rigid conformity or novelty without collapsing into either uncontrolled deviation.

  Towards a theory of human creativity sustained by embodied collective intelligence · 2026 · DOI

• The conjunction map classification requires voxel-level concordance across both modalities (fMRI and MEG) to assign labels, which may be overly stringent and eliminate voxels showing robust effects in single modalities. The paper does not systematically quantify how many social interaction and ToM-responsive voxels are filtered out by this conservative cross-modality approach or test whether relaxed conjunction criteria reveal additional modality-general or modality-unique neural systems.

  Common and distinct neural correlates of social interaction processing and theory of mind in narratives · 2026 · DOI

• The study restricted analysis to positive effects (positive t-statistics) for social interaction and theory of mind processing, excluding investigation of negative or suppressed neural responses during social interaction narratives. Future work should characterize whether deactivations in social brain regions and ToM networks convey distinct functional significance and whether the current methodology's exclusion of negative effects obscures important inhibitory mechanisms in social narrative comprehension.

  Common and distinct neural correlates of social interaction processing and theory of mind in narratives · 2026 · DOI

• The Bayes factor threshold selection (BF > 5 for alternative hypothesis, BF < 1/5 for null hypothesis) was chosen heuristically to achieve 'moderate to strong evidence' given the sample size constraint (N=90), but the paper does not validate whether these thresholds are appropriate for controlling false positive and false negative rates in social cognition neuroimaging or compare sensitivity/specificity against alternative threshold schemes.

  Common and distinct neural correlates of social interaction processing and theory of mind in narratives · 2026 · DOI

• The study employed a conservative conjunction classification approach across fMRI and MEG modalities requiring identical voxel labels in both modalities, but did not explore how modality-specific neural signatures of social interaction processing and theory of mind differ when modalities are analyzed independently. Future work should systematically compare the spatial overlap and divergence of social interaction and ToM activations between fMRI and MEG to determine whether the modality-general constraints artificially suppress modality-specific findings.

  Common and distinct neural correlates of social interaction processing and theory of mind in narratives · 2026 · DOI

• The fMRI general linear model for the Ultimatum Game included parametric regressors for U-strategy and A-strategy but did not explicitly model alpha oscillation-based modulation of these learning computations during feedback processing. The neural mechanisms by which alpha oscillations in the temporoparietal junction causally influence trial-by-trial fluctuations in strategy expression remain unmapped.

  Alpha oscillations in the temporoparietal junction causally shift feedback-based social learning computations in strategic negotiation · 2026 · DOI

• The Monte Carlo simulation procedure for assessing strategic shift significance resamples parameters from null-centered posteriors preserving empirical variance, but whether this approach adequately controls Type I error rates and maintains proper false positive rates under varying levels of inter-individual heterogeneity in the social learning parameters has not been formally tested.

  Alpha oscillations in the temporoparietal junction causally shift feedback-based social learning computations in strategic negotiation · 2026 · DOI

• TMS-EEG stimulation targets were individually defined based on BOLD activations from a False Belief task but constrained to a population-level cluster from only 17 independent participants. The generalizability of this localization approach and whether it adequately captures individual variability in temporoparietal junction anatomy across larger and more diverse samples remains unexamined.

  Alpha oscillations in the temporoparietal junction causally shift feedback-based social learning computations in strategic negotiation · 2026 · DOI

• The individual strategic shift analysis relies on conjunction criteria (βU,hum < 0 AND βA,hum > 0 with 95% HDI excluding zero) to classify participants, but the sensitivity and specificity of this classification threshold relative to alternative decision rules (e.g., 90% HDI, single-parameter thresholds) in predicting negotiation performance has not been systematically evaluated.

  Alpha oscillations in the temporoparietal junction causally shift feedback-based social learning computations in strategic negotiation · 2026 · DOI

• The hierarchical Bayesian modeling approach estimated only learning parameters (α) at the individual subject level due to computational constraints, while β parameters were estimated hierarchically. This mixed estimation strategy has not been validated against fully hierarchical parameter estimation across all model parameters in complex social learning tasks, potentially biasing model comparison outcomes for behavioral, EEG, and human-interaction experiments.

  Alpha oscillations in the temporoparietal junction causally shift feedback-based social learning computations in strategic negotiation · 2026 · DOI

• Most, Scholl, Clifford, & Simons, 2005), but the work in this area is generally limited to attentional sets based on physical features of characters or objects moving around on a screen or the meaning of words and simple pictures being presented on a monitor.

  Noticing of an Unexpected Event is Affected by Attentional Set for Expected Action · 2010

• Although previous studies have found that imagined interactions (IIs) help individuals recall past interactions and plan for future interactions, they have not investigated what occurs when individuals imagine the interactions of others.

  Third-Party Imagined Interactions: Expanding Mental Imagery to the Experience of others' Communication · 2010 · DOI

• Despite the wealth of evidence detailing the existence of a mirror neuron system (MNS) in the adult brain, little is known about its normal development.

  The mirror neuron system: grasping others’ actions from birth? · 2007 · DOI

• Several limitations of the current study warrant consid- eration. Second, a methodologi- cal limitation of the current study lies in the selection and consistency of functional connectivity metrics.

  Neural synchrony and cognitive map formulation in collaborative navigation: leader-follower couplings revealed by EEG hyperscanning · 2026 · DOI

• Empathy enables individuals to attune to others' experiences through shared affective, sensorimotor, and neural representations, but its influence on higher-level decision-making and social alignment remains unknown.

  Shared Pain, Shared Decisions: How Empathy Shapes Social Conformity Through Physiology and Visual Attention · 2026 · DOI

• In an era where global education policies increasingly emphasize whole-child development and cultural sustainability, such pedagogical innovations are promising, though further replication and refinement are warranted.

  Embodied nursery rhyme teaching shows preliminary efficacy for preschoolers’ language aesthetic ability: a pilot mixed-methods study from China · 2026 · DOI

• The remote experiment assessed the importance of face-to-face experience on learning strategies, but lacked neural synchrony data collection to directly compare with the main in-person experiment.

  Enhanced word learning and neural synchrony during children’s storytelling · 2026 · DOI

• Although previous studies have uncovered the positive effects of gestures on communication, little is known about the specific cognitive functions of different types of gestures, or the instantaneous multi-brain dynamics.

  Dynamic brain networks in spontaneous gestural communication · 2024 · DOI

• However, it remains unknown if control is required only when conflict arises between multiple, strongly supported interpretations, or even when there is substantial evidence for one interpretation and competition from weak alternatives.

  Does cognitive control modulate referential ambiguity resolution? A remote visual world study · 2024 · DOI

• In accordance with that tone, the naturally occurring dynamics of moving in and out of synchrony have rarely been studied or considered as an adaptive state.

  In and out of synchrony—Behavioral and physiological dynamics of dyadic interpersonal coordination · 2020 · DOI

• Studies that reported the strongest evidence for symmetry used successive matching-to-sample procedures that included training on both symbolic and identity relations, and studies finding mixed evidence employed alternative methods.

  An update on the search for symmetry in nonhumans · 2020 · DOI

Most-cited papers in Action Observation and Synchronization

• Toward a hierarchical model of social cognition: A neuroimaging meta-analysis and integrative review of empathy and theory of mind. · Psychological Bulletin · 2020 · 498 citations
• In and out of synchrony—Behavioral and physiological dynamics of dyadic interpersonal coordination · Psychophysiology · 2020 · 224 citations
• What Happened to Mirror Neurons? · Perspectives on Psychological Science · 2021 · 189 citations
• The mirror neuron system: grasping others’ actions from birth? · Developmental Science · 2007 · 165 citations
• From Gaze Perception to Social Cognition: The Shared-Attention System · Perspectives on Psychological Science · 2021 · 110 citations
• Connecting and considering: Electrophysiology provides insights into comprehension · Psychophysiology · 2021 · 104 citations
• Power changes how the brain responds to others. · Journal of Experimental Psychology General · 2013 · 101 citations
• Social Networks and Cognition · Annual Review of Sociology · 2020 · 99 citations
• The role of sensorimotor experience in the development of mimicry in infancy · Developmental Science · 2018 · 71 citations
• Eye Movements During Action Observation · Perspectives on Psychological Science · 2015 · 70 citations

Most recent work

• Measuring Semantic Deviation: Operationalizations, Experiments, and Falsification Conditions for a Theory of Meaning as Field Deformation · Zenodo (CERN European Organization for Nuclear Research) · 2026
• Alpha oscillations in the temporoparietal junction causally shift feedback-based social learning computations in strategic negotiation · bioRxiv (Cold Spring Harbor Laboratory) · 2026
• The Coordination-Rapport Link, Revisited: A Study with Automated Coding Techniques · Journal of Nonverbal Behavior · 2026
• Language as a mental capacity · Frontiers in Language Sciences · 2026
• Sensory-motor control with large language models via iterative policy refinement · Scientific Reports · 2026
• Enhanced word learning and neural synchrony during children’s storytelling · npj Science of Learning · 2026
• Dynamic spatiotemporal features in action recognition: a multimodal study · Communications Biology · 2026
• Common and distinct neural correlates of social interaction processing and theory of mind in narratives · Nature Communications · 2026
• Goal-directed action planning modulates surround suppression in the visual system · The Journal of Neuroscience · 2026
• Towards a theory of human creativity sustained by embodied collective intelligence · Frontiers in Psychology · 2026

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