Since at least Aristotle, writers and scholars have debated what makes for a great story. One of them is Samsun Knight, a novelist who is also an economist and assistant professor of marketing at the University of Toronto’s Rotman School of Management. With a scientist’s tools, he’s done what previous theorizers have failed to: put theory to the test and demonstrate the key factor for empirically predicting which stories will be snore fests and which will leave audiences hungry for more.

It turns out to be “narrative reversals” -- lots of them and the bigger the better. Commonly known as changes of fortune or turning points, where characters’ fortunes swing from good to bad and vice versa, Knight and fellow researchers found that stories rich in these mechanisms boosted popularity and engagement with audiences through a range of media, from television to crowdfunding pitches.

“The best-written stories were always either ‘building up’ a current reversal, or introducing a new plot point,” says  Knight. “In our analysis, the best writers were those that were able to maintain both many plot points and strong build-up for each plot point across the course of the narrative.”

The researchers analyzed nearly 30,000 television shows, movies, novels, and crowdfunding pitches using computational linguistics, a blend of computer science and language analysis. This allowed them to quantify not only the number of a reversals in a text but also their degree or intensity by assigning numerical values to words based on how positive or negative they were.

Movies and television shows with more and bigger reversals were better rated on the popular ratings site IMDb. Books with the most and biggest reversals were downloaded more than twice as much as books with the fewest reversals from the free online library Project Gutenberg. And GoFundMe pitches with more and larger reversals were more likely to hit their fundraising goal, by as much as 39 per cent.

The Greek philosopher Aristotle was the first to identify peripeteia, the sudden reversal of circumstances, as a key feature of a good story. Other thinkers have added their ideas since then, including American playwright and dramaturg Leon Katz whose scholarship particularly inspired  Knight’s research. Katz “described the reversal as the basic unit of narrative, just as a sentence is the basic unit of a paragraph, or the syllogism is the basic unit of a logical proof,” says Knight.

In addition to helping psychologists understand how narrative works to educate, inform and inspire people, the findings may also benefit storytellers of all kinds.

“Hopefully our research can help build a pedagogy for writers that allows them to rely on the accumulated knowledge of Aristotle et al. without having to ‘reinvent the wheel’ on their own every time,” says Knight.

That includes himself. With another novel on the way, he was recently working on a chapter with a big reveal. “I realized that this drop might hit harder if I gave the character more positive moments before pulling the rug out from under them,” he says.

The research was co-authored with Matthew D. Rocklage and Yakov Bart, both of Boston’s Northeastern University. It appears in Science Advances.