Even a brief hallway greeting measurably increases later helpfulness toward a stranger.

Evidence

Experimental social psychologists have uncovered striking evidence that even the most casual social interaction can have a powerful effect on reciprocity. When a confederate “stranger” speaks briefly in the hallway to an unwitting subject, the subject is quicker to provide help when she subsequently “overhears” the confederate having an apparent seizure than if there had been no previous contact. — Robert D. Putnam, Bowling Alone The Collapse and Revival…, 2672

Categorization

• XREF: Connects to the book’s central theme of declining social capital: micro-contacts like a hallway greeting are measurable bonding acts whose loss matters. Also echoes the unresponsive-bystander research canon alongside the Milgram and Darley studies. — connects to: Received kindness makes recipients more likely to help others — Robert D. Putnam, Bowling Alone The Collapse and Revival…, 400

Broader Connections

• Received kindness makes recipients more likely to help others #expands (0.85) — Robert D. Putnam, Bowling Alone The Collapse and Revival…, 400