People-calculating: open doors and closed doors

Whether one person holds a door open for another is not simply a question of etiquette, says a study by Joseph P Santamaria and David A Rosenbaum [pictured here] of Pennsylvania State University. No, they say. Nothing simple about it.

Santamaria and Rosenbaum worked to pursue the answer through a tangle of belief, logic, probability, perception and calculation. Their study, Etiquette and Effort: Holding Doors for Others, was published in 2011 in the journal Psychological Science. It is, one way or another, a gripping read....

—So begins the latest Improbable Research column in The Guardian.

BONUS: This graph is from an economist’s alternative take on the question: