Social Neuroscience and Interbrain Synchrony
Hyperscanning Methodologies
Beyond the Single Brain
Traditional social neuroscience studies "spectator" social cognition. Hyperscanning involves simultaneously recording brain activity from two or more interacting individuals to study interbrain synchrony (IBS). Phase-Locking Value (PLV) is often used to quantify phase synchronization between two brains across trials:
fNIRS vs. EEG for Hyperscanning
fNIRS (Functional Near-Infrared Spectroscopy)
- Measures cortical hemodynamics (oxygenated/deoxygenated hemoglobin).
- Highly tolerant to motion artifacts.
- Excellent for naturalistic, face-to-face interactions.
EEG (Electroencephalography)
- Measures electrical activity.
- Highly susceptible to muscle and motion artifacts.
- Requires participants to remain relatively still, limiting ecological validity.
Spurious Synchrony
A major challenge in hyperscanning is distinguishing true social synchronization from spurious synchrony caused by shared sensory input or identical motor responses. Advanced experimental designs use staggered interactions or pseudo-pairs as control conditions.
What does the Phase-Locking Value (PLV) measure in hyperscanning studies?
PLV measures the stability of the phase difference between two signals. If the phase difference is constant over time, PLV approaches 1, indicating high synchronization.
Correct answer: The consistency of phase differences between two signals over time.
What neuroimaging technique uses near-infrared light to measure cortical hemodynamics and is highly portable, making it popular for hyperscanning?
Functional Near-Infrared Spectroscopy (fNIRS) is portable and motion-tolerant, ideal for studying naturalistic social interactions.
Correct answer: fNIRS
Analyzing Hyperscanning Data
-
1
Signal Preprocessing: Filtering, artifact rejection, and spatial registration.
-
2
Time-Frequency Decomposition: Using Wavelet transforms or Hilbert transforms to extract phase and amplitude.
-
3
Synchrony Computation: Calculating metrics like PLV, Wavelet Transform Coherence (WTC), or Granger Causality.
-
4
Statistical Testing: Comparing true interacting pairs against shuffled surrogate pairs to rule out spurious synchrony.