Fouloscopie: Ce que la foule dit de nous – Mehdi Moussaïd

Thoughts: A highly enjoyable book. I became aware of Fouloscopie because of the author’s excellent YouTube channel of the same name, where Moussaïd makes videos on the science of crowds. Lots of neat insights from a variety of different fields, interspersed among many anecdotes from the author’s life and research (while they were lively and often quite funny, I could have done with a somewhat higher science-to-anecdote ratio). Good source of new vocabulary, with all its colourful descriptions.

(The notes below are not a summary of the book, but rather raw notes - whatever I thought, at the time, might be worth remembering. I read this as an e-book, so page numbers are as they appeared in Apple Books.)

Moussaïd, Mehdi. 2019. Fouloscopie: Ce que la foule dit de nous. HumenSciences.

1. Le Baptême

2. Piétons, fourmis et grains de riz

3. Le Piéton particule

• 33: In the early 1970s, Leroy Henderson proposed that the movements of crowds could be modelled like the flow of a liquid. “Il trouvait qu’une foule qui marche dans une rue ressemble à un liquide qui s’écoule le long d’un tuyau…. Un déplacement lent s’apparenterait à un liquide visqueux, tandis qu’une foule agitée serait un liquide en ébullition.”
• 34: This model has been highly successful, but one interesting difference between crowds and particles has been observed. In both crowds and fluids, particles sometimes clump together. But whereas clumps in a fluid move in the most aerodynamic way possible, clumps of people often do the opposite: whereas a group of three people might be expected to form an arrowhead shape, groups of three will instead form a V with two people in front and one person behind. This arrangement allows all three people in the group to converse, make eye contact, etc. with each other person.
• 37: Moussaïd tried to build a model where each simulated pedestrian/particle interacted with its neighbours in a more “human” way. He found that it performed well when densities were low, accurately modeling how crowds actually moved, but when densities were higher and the movements of individuals were more limited, the model began to break down - i.e. in exactly those situations where the fluid models performed best.

4. Bienvenue chez les psys

5. Turbulences

6. J’Irai où tu iras

7. Panique à Pandora

8. L’Aide ou La Fuite

9. Épidémies d’information

• 92: Quote attributed to Mark Twain: “Un mensonge peut faire le tour du monde le temps que la vérité mette ses chaussures” - something along the lines of “A lie can travel around the world in the time it takes for the truth to put on its shoes”.

10. La Toile

11. Mille Jugements en un

• 113: in order for the wisdom of crowds to work, several conditions must be satisfied:
  • people must have at least some idea about the correct answer
  • people’s errors in judgement must be different - “La diversité des jugements, donc des erreurs, est indispensable au bon fonctionnement de la sagesse des foules”
    • social influence can very easily disrupt this second condition - as soon as even one person’s guess is known, it begins to affect everyone’s estimates
      • cf. j: anchoring bias?

12. À L’Aube d’un nouveau jour

Postface