“Biases in the perception of drinking norms among college students” by Baer et al (1991)

“The Majority Illusion in Social Networks” by Lerman et al (2016).
Related: The Friendship Paradox.

From Nicholas Christakis and James Fowler's wonderfully-written, layperson-accessible book, Connected (2009).

“Suicide Contagion and the Reporting of Suicide: Recommendations from a National Workshop” by O'Carroll et al (1994), endorsed by the frickin' Centers for Disease Control & Prevention (CDC).

“Contagion in Mass Killings and School Shootings” by Towers et al (2015).

Also see: the Don't Name Them campaign, which urges that news outlets DO NOT air mass murderers' names, manifestos, and social media feeds. This spreads the contagion. Instead, news outlets should focus on the victims, first responders, civilian heroes, and the grieving, healing community.

“Lemmings of Wall Street” by Cass Sunstein, is a quick, non-technical read. Published in Oct 2008, right in the wake of the crash.

“Threshold Models of Collective Behavior” by Granovetter (1978) was the first time, as far as I know, anyone described a "complex contagion" model. (although he didn't use that specific name)

“Evidence for complex contagion models of social contagion from observational data” by Sprague & House (2017) shows that complex contagions do, in fact, exist. (at least, in the social media data they looked at)

Finally, “Universal behavior in a generalized model of contagion” by Dodds & Watts (2004) proposes a model that unifies all kinds of contagions: simple and complex, biological and social!

arranged in a ring of 12 nipples, plus one in the middle

This Orwell-inspired phrase was coined by Irving L. Janis in 1971. In his original article, Janis investigates cases of groupthink, lists its causes, and — thankfully — some possible remedies.

These two types of social capital — "bonding" and "bridging" — were named by Robert Putnam in his insightful 2000 book, Bowling Alone. His discovery: across almost all empircal measures of social connectiveness, Americans are more alone than ever. Golly.

“The Strength of Weak Ties” by Granovetter (1973) showed that connections across groups helps spread simple contagions (like information), but “Complex Contagions and the Weakness of Long Ties” by Centola & Macy (2007) showed that connections across groups may not help complex contagions, and it fact, can hurt their spread!

The idea of the "small world" was popularized by Travers & Milgram's 1969 experiment, which showed that, on average, any two random people in the United States were just six friendships apart — "six degrees of separation"!

The small-world network got more mathematical meat on its bones with “Collective dynamics of small-world networks” by Watts & Strogatz (1998), which proposed an algorithm for creating networks with both low average path length (low degree of separation) and high clustering (friends have lots of mutual friends) — that is, a network that hits the sweet spot!

You can also play with the visual, interactive adaptation of that paper by Bret Victor (2011).

“Small-world brain networks” by Bassett & Bullmore (2006).

“Collaboration and Creativity: The Small World Problem” by Uzzi & Spiro (2005). This paper analyzed the social network of the Broadway scene over time, and discovered that, yup, the network's most creative when it's a "small world" network!

See “Social Physics” by MIT Professor Alex "Sandy" Pentland (2014) for a data-based approach to collective intelligence.

Besides the NASA Challenger explosion, the most notorious example of groupthink was the Bay of Pigs fiasco. In 1961, US President John F. Kennedy and his team of advisors thought — for some reason — it would be a good idea to secretly invade Cuba and overthrow Fidel Castro. They failed. Actually, worse than failed: it led to the Cuban Missile Crisis of 1962, the closest the world had ever been to full-scale nuclear war.

Yup, JFK really screwed up on that one.

But, having learnt some hard lessons from the Bay of Pigs fiasco, JFK re-organized his team to avoid groupthink. Among many things, he: 1) actively encouraged people to voice criticism, thus lowering the "contagion threshold" for alternate ideas. And 2) he broke his team up into sub-groups before reconvening, which gave their group a "small world network"-like design! Together, this arrangement allowed for a healthy diversity of opinion, but without being too fractured — a wisdom of crowds.

And so, with the same individuals who decided the Bay of Pigs, but re-arranged collectively to decide on the Cuban Missile Crisis... JFK's team was able to reach a peaceful agreement with Soviet leader Nikita Khrushchev. The Soviets would remove their missiles from Cuba, and in return, the US would promise not to invade Cuba again. (and also agreed, in secret, to remove the US missiles from Turkey)

And that's the story of how all of humanity almost died. But a small world network saved the day! Sort of.

You can read more about this on Harvard Business Review, or from the original article on groupthink.

Again, from Nicholas Christakis and James Fowler's wonderful book, Connected (2009).

yes, including the ideas in this explorable explanation.

The keyboard shortcuts (1, 2, space, delete) work in all the puzzles, not just Sandbox Mode! Seriously, you can go back to a different chapter, and edit the simulation right there. In fact, that's how I created all these puzzles. Have fun!

To my supporters on Patreon: I'm deeply grateful. Your generosity literally feeds me and pays my rent, and grants me the creative freedom to make these weird math/social-science games. From the bottom of my heart, thank you!

Thank you, everyone who playtested Crowds during its many stages of life!

The Prototype:
Maria · Monica Srivastava

The Alpha:
Glen Chiacchieri · Kalli Repzeti · Mali Akmanalp · Toph Tucker

The Beta:
Alex Dytrych · Amit Patel · Cassandra McClure · Catherine Ray · Josh Comeau · Kayle Sawyer · Matthew Conlen · Srini Kadamati · Vanessa Shen · Wick Perry