Information Cascades and Mass Movements
https://www.economist.com/democracy-in-america/2011/10/26/information-cascades
An information cascade is essentially a phenomenon in which a series of people make the same decision sequentially by following the behavior of the people before them. This has the potential to result in a population-wide outcome. The Economist introduces the concept of an information cascade through several examples such as: stock prices, protests, and dissemination of information. I believe the most interesting example of an information cascade was given by their discussion of stock prices. Based on their explanation, if a stock price falls, many people start to sell which drives price down and vice versa happens if the stock price rises. This is reminiscent of the initial example of information cascades in the textbook concerning the decision about which restaurant to go to.
In the textbook example, we are given the following situation. There are two restaurants (A and B) and based on your own research you choose to go to restaurant A. However, when you arrive there are no patrons at restaurant, but restaurant B has many people waiting in line. Therefore, no matter your own personal research, the rational decision would be to join the line at restaurant B. Similar to the stock prices, even if you have a good understanding of why the stock prices dropped that day (say it had to do with a government announcement) but you were confident the stock prices would raise the next day, if everyone begins to sell their stocks you might consider selling your shares too despite your personal knowledge. I suppose we would normally call this second guessing yourself. Obviously without any discussion, it is impossible to know exactly why other people are making their respective decisions and thus it makes it difficult to weigh your knowledge against theirs. Therefore, I suppose it makes logical sense that if you see everyone else choose a choice that runs counter to your own, you should follow them and ignore your own knowledge/decision. If everyone chooses a different choice than you, it would stand to reason that their information is more accurate than yours. Thus, in other words, an information cascade has started.