Measuring social capital with a myograph

We study the behavior of 12 pairs of undergraduate students while they were involved in a simple coordination game requiring motor interaction. Three experimental conditions were defined according to whether a monetary prize was given to both or only one subject, if the couple was in successfully completing the required assignment. Electromyographic potentials (EMG) were recorded from the right first dorsal interosseus (FDI) muscle, a muscle critically involved in the motor task. We also collected written answers from a standard questionnaire from which we constructed individual measures of Social Capital (SC), based on organized group interaction, religious and political involvement. These measures are collected, by standard practice, to estimate individual pro-social attitudes and behavior. Consistently with our simple behavioral model, by which EMG signals are direct measures of subjects’ personal concern (call it utility) associated to the given task, our evidence shows that EMG is increasing in the subjects’ own monetary reward. When we split the subject pool into two subsamples (according to various measures of Social Capital obtained from the questionnaire), we find that monetary incentives explain the level of subjects’ EMG only in the subsample characterized by low SC, while, for subjects with (comparatively) higher SC, effort in the coordination task is much less sensitive to whether it is directly rewarded or not. This result is robust across the different SC index specifications. The present findings seem to support the possibility that an electrophysiological measure, such as EMG, could reveal the most profound attitudes and believes that guide social interaction, and that our relatively inexpensive and ready-to-use technology can back-up socio-economic research in a very effective way.