Did we see someone shake hands with a fire hydrant?: collaborative recall affects false recollections from a campus walk.

An experimenter presented familiar and bizarre action statements (e.g., "Rest on the fire hydrant" vs. "Shake hands with the fire hydrant") to a participant and confederate during a campus walk. They watched the experimenter perform half the actions and imagined the experimenter performing the other half. One day later, they took a second walk where actions were only imagined. Some actions from the first walk were repeated, and new actions were added. Two weeks later, the participant and confederate collaboratively recalled whether specific actions were presented in the first walk and, if so, whether they were imagined or performed. For different actions, the confederate was accurate, was inaccurate, or provided no information. When later tested individually, participants demonstrated imagination inflation by falsely remembering familiar and bizarre actions as performed on the first walk that were merely imagined on the second. These memory errors were greatly reduced if the confederate was accurate during collaborative recall.