Interbrain synchrony: on wavy ground

Interbrain synchrony is a putative neural mechanism said to promote social interactions by enabling the functional integration of multiple brains. Research on this topic has skyrocketed in recent years. However, the field lacks a widely accepted definition of interbrain synchrony. Interbrain synchrony wants for theories that can guide the design and interpretation of experiments. A plethora of empirical methods permit evidence consistent with the idea to accumulate without providing means to falsify it. These problems conspire to undermine the construct validity of the phenomenon. However, steps can be taken to address these issues. In recent years the study of dynamic, between-brain coupling mechanisms has taken social neuroscience by storm. In particular, interbrain synchrony (IBS) is a putative neural mechanism said to promote social interactions by enabling the functional integration of multiple brains. In this article, I argue that this research is beset with three pervasive and interrelated problems. First, the field lacks a widely accepted definition of IBS. Second, IBS wants for theories that can guide the design and interpretation of experiments. Third, a potpourri of tasks and empirical methods permits undue flexibility when testing the hypothesis. These factors synergistically undermine IBS as a theoretical construct. I finish by recommending measures that can address these issues. In recent years the study of dynamic, between-brain coupling mechanisms has taken social neuroscience by storm. In particular, interbrain synchrony (IBS) is a putative neural mechanism said to promote social interactions by enabling the functional integration of multiple brains. In this article, I argue that this research is beset with three pervasive and interrelated problems. First, the field lacks a widely accepted definition of IBS. Second, IBS wants for theories that can guide the design and interpretation of experiments. Third, a potpourri of tasks and empirical methods permits undue flexibility when testing the hypothesis. These factors synergistically undermine IBS as a theoretical construct. I finish by recommending measures that can address these issues. electrophysiological oscillations spanning, in humans, frequencies between about 8 and 12 Hz. electrophysiological oscillations spanning, in humans, frequencies between about 12 and 30 Hz. a measure of the association between angular variables, which is useful for assessing correlations between phases of neural oscillations. the predisposition to favor evidence supporting one’s own hypothesis over evidence contradicting that hypothesis. a network of brain areas, including the medial prefrontal cortex, precuneus, posterior cingulate cortex, and inferior parietal cortex. Although the DMN was first identified because it becomes relatively active when subjects are at rest, it is now understood to play an important role in social behavior and other high-level functions. electrophysiological oscillations spanning, in humans, frequencies between about 1 and 4 Hz. neural information about a motor command processed by brain areas not directly involved in the execution of that command. electrophysiological oscillations spanning, in humans, frequencies greater than about 30 Hz. a statistical method for testing whether a given time series is predictive of a second time series. the mathematical study of structures built from elements (called ‘nodes’) and their pairwise relationships (called ‘edges’). ‘hypothesizing after the results are known’. When experimenters report a post hoc interpretation of their results as an a priori prediction. This is considered bad practice because it violates principles of statistical inference. experimental techniques that simultaneously record the brain activities of two or more individuals. a method for analyzing brain activity elicited by naturalistic stimuli and tasks. The method identifies spatio-temporal patterns of neural activity that are statistically reliable across subjects. a questionable research practice whereby experimenters mine their data for results that support their hypotheses without divulging that these analyses are exploratory. a statistical measure of brain connectivity that provides a frequency-domain measure of Granger causality. the fraction of one cycle of an oscillation relative to the onset of that cycle. a measure of phase synchrony between time series that is independent of signal amplitude. near-instantaneous change in phase of an ongoing neural oscillation elicited by the occurrence of an internal or external stimulus. widespread concern throughout multiple branches of science, beginning in the 2010s, that many published and highly regarded experimental findings fail to replicate. This concern has been especially acute in the social sciences. as applied in some interbrain synchrony studies, a control analysis whereby the data of dyad members are randomly interchanged across pairs only a single time (in contrast to permutation analysis, which entails interchanging the data across dyads multiple times). electrophysiological oscillations spanning, in humans, frequencies between about 4 and 8 Hz.