The parents identified events that had and had not happened to their kids — and generated two events that were plausible but had not happened. The researchers then asked the test subjects to recall each event, true or not, including details like who was present and when it happened.

They met multiple times; by the third session, most participants at least believed the false events had happened. More than half had developed actual false memories of them.

This wasn’t the first time researchers have demonstrated how easy it can be to implant false memories. But it was the first time they tried to reverse them — without revealing to the subjects what had happened.

They found two key methods helped participants differentiate their own real recollections from the false ones:

— Asking them to recall the source of the memory
— Explaining to them that being pressured to recall something multiple times can induce false memories