This is Hidden Brain. I'm Shankarvedantem. In 1980, a bomb exploded at the central train station

in Bologna, Italy. 85 people were killed. Hundreds were injured. In the wake of the attack, which was later blamed on an

Italian terrorist organization, a large clock on the outside of the train station

stopped working. The clock, frozen at 1025, became a symbol of the attack.

The picture of the clock was plastered all over posters and banners during commemorations

of the event for years afterwards.

The clock was quickly repaired, but in 1996, 16 years after the bombing, city officials

permanently stopped the clock at 1025 in

remembrance of the tragedy. In so doing, they unwittingly set up a psychological

experiment. Decades later, when asked whether the clock had ever been

fixed, the vast majority of city residents incorrectly reported that it had not. That included 21 employees of the train station who presumably saw the clock on a

regular basis. It's not difficult to understand how this error might have come about.

The stop clock had become an integral element of the story of the bombing.

People's recollections were shaped by the story as much as the facts.

We see the same thing happening in settings large and small.

Two friends might disagree about an incident that took place

when they were in school together years before.

Managers and workers may remember different versions of the events that led to a strike,

with each group partial to the version that supports its point of view.

When countries go to war, millions of people may collectively remember one chronicle or historical wrongs,

while millions of people on the other side of a border remember a completely

different set of facts.

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