Can communication across networks of people be optimized to share information, while at the same time lessening the likelihood of information bubbles and echo chambers? In Episode 54, we’re joined by Ida Momennejad and Ajua Duker from Columbia University and Yale University, respectively, to discuss their open-access article “Bridge ties bind collective memories” which was published with Alin Coman on April 5, 2019 in the journal Nature Communications.

Collective Memories - Ida Momennejad & Ajua Duker
Collective Memories - Ida Momennejad & Ajua Duker
Collective Memories - Ida Momennejad & Ajua Duker Collective Memories - Ida Momennejad & Ajua Duker
@rwatkins says:
Given the polarization of the American electorate leading into the 2020 presidential election, we were interested in learning Ida and Ajua’s thoughts on what we might do to diminish our information bubbles and echo chambers even when we might not realize that they constrain us.
@rwatkins says:
The participants in their study tended to communicate differently when they did so when interacting within their in-groups, as opposed to when doing so across social groups. We were interested in hearing Ida and Ajua’s thoughts on why this might be the case.
@rwatkins says:
Ida and Ajua’s study tracked the sharing of information both within groups and across groups in order to track how that sharing influenced the collective memory of the groups. This required sophisticated network analysis techniques, so Doug and I asked Ida to tell us more about their analytical approach.
@rwatkins says:
Before the break, Ida was about to provide an example of how bridge ties might operate in a conversation among a group of people.
@rwatkins says:
Ida and Ajua’s study was designed to end after the fourth round of communication among participants, with some groups just getting information for the first time from bridge ties. This led Doug and I to wonder what they believe might have happened had the conversations continued beyond four rounds.
@rwatkins says:
Though their study was carried out via internet chat, speech is the primary vehicle by which people tend to interact in life. So given what we had just discussed, Ryan and I were interested in hearing their thoughts on how we might apply their findings to this more common mode of communication.
@rwatkins says:
Ida and Ajua’s study illustrates the importance of when people share information across different groups with which they interact. We followed up with Ida to learn about the potential policy implications and applications of their research.
@rwatkins says:
Ryan and I wondered to what extent Ida and Ajua might feel that the social position of bridge ties might have an influence on the saliency of their ability to connect diverse clusters of people.
@rwatkins says:
While clustering can enhance the prevalence of shared memories among a group of friends, Doug and I wondered if there might also be a darker side to such collective memory. Here’s what Ida had to say about the question.
@rwatkins says:
The article that Ajua mentioned, which participants read in their experiment, could be said to be something of a rather unusual short story. Weighing in at just 384 words, it’s a tale of two boys who skip school and visit one of the boy’s houses. If you’re interested in reading it, you can do so at: We asked Ida to tell us about the story’s origin and uses.
@rwatkins says:
Next, Ajua explains how she and Ida set up their experiments to mimic these kinds of within group and between group relationships that happen all around us.
@rwatkins says:
Ida and Ajua’s study is an application of a theory regarding the spread of information among social networks popularized by Stanford University sociologist Mark Granovetter, in 1973. He proposed that when two people are interpersonally connected, their groups of friends are more likely to share common memories of their experiences. The model explains how close-knit clusters of friends can be formed both by the strong ties among groups of friends as well as by weak ties that bridge between two or more clusters of friends. We began by asking Ida for an example of how such groups might share common memories of shared experiences in everyday life.
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Websites and other resources

Ida’s workshop on graphs and collective memory:



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Hosts / Producers

Doug Leigh & Ryan Watkins

How to Cite

Leigh, D., Watkins, R., Momennejad, I., & Duker, A.. (2019, July 23). Parsing Science – Collective Memories. figshare.


What’s The Angle? by Shane Ivers


Ida Momennejad: An important aspect was how much there is overlap in the information that is shared over time in the network, and how much there is the diversity of information.

Doug Leigh: This is Parsing Science. The unpublished stories behind the world’s most compelling science as told by the researchers themselves. I’m Doug Leigh …

Ryan Watkins: And I’m Ryan Watkins. Today in episode 54 of Parsing Science, we’ll be joined by Ida Momennejad and Ajua Duker from Columbia University and Yale University. They’ll discuss their research into how communication across networks of people can optimize information sharing while diminishing the likelihood of information bubbles and echo chambers. Here’s Ida Momennejad and Ajua Duker.

Momennejad: Hello! I’m Ida Momennejad. I’m currently a research scientist at Columbia University, and I used to be a postdoc at Princeton when I collaborated with Ajua and Alin on this project. I’m originally from Tehran, Iran, and I did my undergrad in computer science, software engineering, and then I went on to the Netherlands and did a graduate degree in philosophy of science and philosophy of mind, and from there I went to Berlin and did my PhD in computational neuroscience and psychology. The entire sort of background of mine is very much centered around building computational models of how people think or designing experiments to understand how their brains represent the future in particular, and what is the relationship between memories of the past and representations of future, how these sort of representations inside the brain get updated, and how they lead to decisions in people.

Ajua Duker: And my name is Ajua Duker. I’m currently a second year PhD student at Yale, I’m in the social psychology department. So after I graduated college, I ended up being a research assistant at Princeton, which is where I met Ida and Alin who I had the awesome opportunity to work with. And there, I did work with Alin on stuff having to do with memory, stuff having to do with retrieval-induced forgetting, and we did a lot of social network studies which is sort of the paper that I worked on with Ida as well. Just a little bit more about me as a person, so both of my parents were born in Ghana but I was born here in the US, but I have a lot of ties to home, I have a huge Canadian family that’s a big part of my life. And then also I dance still even as a grad student, but I used to train in classical ballet pretty much all through my childhood and high school.

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