The study, online in the Journal of Consumer Research, looked at a total of just over 500 people in five different tests. Both in the lab and on the street, people were asked to engage in some sort of free support for a cause, like joining a Facebook group or wearing a pin. The researchers found that more public displays of endorsement made people less likely to volunteer their time or financial support for a cause later. More private displays of support, like signing a petition, resulted in a greater likelihood of giving later.