Afew years ago a student walked into the office of Cesar A. Hidalgo, director of the Collective Learning group at the MIT Media Lab. Hidalgo was listening to music and asked the student if she recognized the song. She wasn’t sure. “Is it Coldplay?” she asked. It was “Imagine” by John Lennon. Hidalgo took it in stride that his student didn’t recognize the song. As he explains in our interview below, he realized the song wasn’t from her generation. What struck Hidalgo, though, was the incident echoed a question that had long intrigued him, which was how music and movies and all the other things that once shone in popular culture faded like evening from public memory.
Hidalgo is among the premier data miners of the world’s collective history. With his MIT colleagues, he developed Pantheon, a dataset that ranks historical figures by popularity from 4000 B.C. to 2010. Aristotle and Plato snag the top spots. Jesus is third. It’s a highly addictive platform that allows you to search people, places, and occupations with a variety of parameters. Most famous tennis player of all time? That’s right, Frenchman Rene Lacoste, born in 1904. (Roger Federer places 20th.) Rankings are drawn from, essentially, Wikipedia biographies, notably ones in more than 25 different languages, and Wikipedia page views.
Courtesy of Cesar Hidalgo
Last month Hidalgo and colleagues published a Nature paper that put his crafty data-mining talents to work on another question: How do people and products drift out of the cultural picture? They traced the fade-out of songs, movies, sports stars, patents, and scientific publications. They drew on data from sources such as Billboard, Spotify, IMDB, Wikipedia, the U.S. Patent and Trademark Office, and the American Physical Society, which has gathered information on physics articles from 1896 to 2016. Hidalgo’s team then designed mathematical models to calculate the rate of decline of the songs, people, and scientific papers.
The report, “The universal decay of collective memory and attention,” concludes that people and things are kept alive through “oral communication” from about five to 30 years. They then pass into written and online records, where they experience a slower, longer decline. The paper argues that people and things that make the rounds at the water cooler have a higher probability of settling into physical records. “Changes in communication technologies, such as the rise of the printing press, radio and television,” it says, affect our degree of attention, and all of our cultural products, from songs to scientific papers, “follow a universal decay function.”
Last week I caught up with Hidalgo to talk about his Nature paper. But I also wanted to push him to talk about what he saw between the mathematical lines, to wear the social scientist’s hat and reflect on the consequences of decay in collective memory.
How do you define “collective memory?”
The easiest definition would be those pieces of knowledge or information that are shared by a large number of people.
Why does collective memory decay matter?
If you think about it, culture and memory are the only things we have. We treasure cultural memory because we use that knowledge to build and produce everything we have around us. That knowledge is going to help us build the future and solve the problems we have yet to solve. If aliens come here and wave a magic wand and make everyone forget everything—our cars, buildings, bridges, airplanes, our power systems, and so forth, we would collapse as a society immediately.
The relative power of scientists has diminished as we exited the printing era and went into this more performance-based era.
In your mind, what is a classic example of collective memory decay?
I thought everybody knew “Imagine” by John Lennon. I’m almost 40 and my student was probably 20. But I realized “Imagine” is not as popular in her generation as it was in mine, and it was probably less popular in my generation than in the generation before. People have a finite capacity to remember things. There’s great competition for the content out there, and the number of people who know or remember something decays over time. There’s another example, of Elvis Presley memorabilia. People had bought Elvis memorabilia for years and it was collecting huge prices. Then all of a sudden the prices started to collapse. What happened is the people who collected Elvis memorabilia started to die. Their families were stuck with all of this Elvis stuff and trying to sell it. But all of the people who were buyers were also dying…