Protests can come in many different forms, with some successfully conveying their message and leading to change while others fall flat.

From masses in Iran calling for regime change after the death of a woman in police custody, to protests in the U.S. over abortion access, police violence and climate change, recent protests have cropped up across the globe, including the big oil objectors who threw tomato soup on a Van Gogh painting in London.

What kind of protests are most successful?

Stephen Duncombe, professor, co-founder and research director for the Center for Artistic Activism at New York University, spoke with Jim Braude on Greater Boston about what protests work best to enact change.

Duncombe said protests should be part of a larger campaign, and there should be a direct connection between the action and the message. He noted the protesters who threw soup at the Van Gogh painting had a convoluted connection to their message about big oil.

Some of the best protests come from the U.S. civil rights movement, Duncombe said, such as when Rosa Parks refused to give up her seat on the bus. "It was part of a larger campaign, it was kicking off the campaign, but it was a fully worked out campaign."

Duncombe said boycotting can also be a successful tactic. He saidAdidas recently cut ties with Kanye West over his antisemitic comments due in part to fear of a boycott.

Why are so few protests leading to real change these days?