by a show of hands
Based on a visual representation of interest (indicated by people raising their hands). Class, we'll decide what to do at recess by a show of hands. Who wants to play tag?
by a show of hands
[of a vote taken] expressed by people raising their hands. We were asked to vote for the candidates for captain by a show of hands. Bob wanted us to vote on paper, not by a show of hands, so that we could have a secret ballot.