Dr. Florin Dolcos, of the Beckman Institute for Advanced Science and Technology and the Department of Psychology at the University of Illinois at Urbana-Champaign, along with Sanda Dolcos (University of Illinois), Keen Sung (University of Massachusetts), Jennifer J. Argo (University of Alberta), Sophie Flor-Henry (University of Calgary), performed the research.
Their paper, "The Power of a Handshake: Neural Correlates of Evaluative Judgments in Observed Social Interactions", was published online and in the December 2012 issue of the Journal of Cognitive Neuroscience.
They introduce the topic of handshakes with the following (in their abstract to their paper): "Effective social interactions require the ability to evaluate other people's actions and intentions, sometimes only on the basis of such subtle factors as body language, and these evaluative judgments may lead to powerful impressions. However, little is known about the impact of affective body language on evaluative responses in social settings and the associated neural correlates."
"This study investigated the neural correlates of observing social interactions in a business setting, in which whole-body dynamic stimuli displayed approach and avoidance behaviors that were preceded or not by a handshake and were followed by participants' ratings of these behaviors."
"First, approach was associated with more positive evaluations than avoidance behaviors, and a handshake preceding social interaction enhanced the positive impact of approach and diminished the negative impact of avoidance behavior on the evaluation of social interaction."
"Second, increased sensitivity to approach than to avoidance behavior in amygdala [the part of the brain involved with the processing of memory and emotional reactions] and STS [superior temporal sulcus, the part of the brain that helps people to perceive the movements and emotions of others] was linked to a positive evaluation of approach behavior and a positive impact of handshake."
"Third, linked to the positive effect of handshake on social evaluation, nucleus accumbens [the part of the brain that plays an important role in such emotions as reward, pleasure, laughter, addiction, aggression, fear] showed greater activity for Handshake than for No-handshake conditions."
Thus, "These findings shed light on the neural correlates of observing and evaluating nonverbal social interactions and on the role of handshake as a way of formal greeting."
Page two concludes.