A technical note on the precise timing of behavioral events in economic experiments

The increasing use of physiological recordings in experimental economics requires a precise timing of interesting events, such as the presentation of a set of choices, the decision-making moment and the reception of feedback through the display of a decision outcome. In this note we provide a simple, accurate and inexpensive solution based on the use of external photo-sensors that detect changes in light intensity on the participants’ screens occurring in synchrony with experimental events. This system ensures an accurate communication between standard programs broadly used to run behavioral economic experiments, such as z-Tree, and biosignal acquisition systems recording physiological variables, such as skin conductance, heart rate and electroencephalogram. An example is briefly discussed, offering specific guidelines for the application of this methodology in economic contexts with strategic interaction.