Quick: Which American president served before slavery ended, John Tyler or Rutherford B. Hayes?

If you need Google to get the answer, you are not alone. (It is Tyler.)

Collective cultural memory — for presidents, for example — works according to the same laws as the individual kind, at least when it comes to recalling historical names and remembering them in a given order, researchers reported on Thursday. The findings suggest that leaders who are well known today, like the elder President George Bush and President Bill Clinton, will be all but lost to public memory in just a few decades.

The particulars from the new study, which tested Americans’ ability to recollect the names of past presidents, are hardly jaw-dropping: People tend to recall best the presidents who served recently, as well as the first few in the country’s history. They also remember those who navigated historic events, like the ending of slavery (Abraham Lincoln) and World War II (Franklin D. Roosevelt).

But the broader significance of the report — the first to measure forgetfulness over a 40-year period, using a constant list — is that societies collectively forget according to the same formula as, say, a student who has studied a list of words. Culture imitates biology, even though the two systems work in vastly different ways.