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Phi complex

The phi complex is a brain rhythm in the awake human brain that appears to serve various social functions. Phi is one of several brain rhythms in the awake human brain that coordinate human behavior. 'Phi' operates in the ten Hz band (ten oscillations per second), and is located above the right centro-parietal cortex. It consists of two components, one favoring independent behaviors, and the other favoring interpersonal coordination between people.

The brain wave patterns of the phi complex are consistent with those of waves produced in the human mirror neuron system. The phi complex may reflect the influence of one person upon another's behavior, with phi1 expressing the inhibition of the human mirror neuron system and phi2 its enhancement.


Researchers from from Florida Atlantic University (FAU), in one of the first studies in the field of social neuroscience, have identified neural signatures of effective, real-time coordination between people. FAU researchers have recorded, measured and analyzed both behavior and brain activity simultaneously in two interacting humans that could provide insight into neurological disorders, such as autism and schizophrenia. "The Phi Complex as a Neuromarker of Human Social Coordination", which was published in the Proceedings of the National Academy of Sciences on May 8, 2007.[1]

The research, which utilized a specially designed dual-electroencephalogram (EEG) and the conceptual framework and methods of coordination dynamics, was conducted by Drs. Emmanuelle Tognoli, Julien Lagarde, Gonzalo DeGuzman and J.A. Scott Kelso at FAU's Human Brain and Behavior Laboratory at the Center for Complex Systems and Brain Sciences at the Charles E. Schmidt College of Science.

Using EEG recordings, Tognoli and her colleagues tested the brain activity of two people simultaneously performing continuous finger motion. Initially, two subjects were asked to rhythmically wag their fingers at their own preferential pace, but were prevented from seeing each others’ hands. Then the barrier placed between them was then removed, so they could see each other while contining to wag their fingers. When subjects were allowed to see one anothers’ fingers moving, they sometimes adjusted their own movements and synchronized, and sometimes they did not, behaving independently.

The researchers believe that the use of dual EEG recordings to observe the phi complex could help scientists better understand what triggers leader/follower behaviors and male/female relationships. The researchers reported that 62 percent of respondents synchronized their movements upon being exposed to one another's finger-wagging, but 38 percent were unaffected and continued gesturing independently.

The study demonstrated a clear reduction in occipital lobe alpha wave and mu wave rhythms during social interaction. The evident suppression was independent of whether or not behavior was coordinated. In contrast, a pair of oscillatory components (phi1 and phi2) above the right centro-parietal cortex distinguished effective from ineffective coordination. An increase of phi1 favored independent behavior and increase of phi2 favored coordinated behavior.

According to Kelso, the Glenwood and Martha Creech Eminent Scholar in Science at FAU and founder of the Center for Complex Systems and Brain Sciences, "What this research suggests is that a unique pattern can be seen in the brains of two people interacting and that these brain activities distinguish independence from cooperation. This new brain rhythm that we have discovered and termed the ‘phi complex’ actually distinguishes when you’re socially interacting and when you’re not."

See also

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Phi_complex". A list of authors is available in Wikipedia.
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