PUBLISHERS aren’t just selling stories — they’re selling split-second decisions, from the colour on the jacket to the words you only half-read on the back.

Book designer Jamie Keenan says covers are routinely tested, shown to supermarket buyers and changed if big retailers aren’t keen. He argues those buyers hold serious sway: if a major chain doesn’t like a design, it can be back to the drawing board.

Online shopping has cranked up a different pressure: the “thumbnail” problem. Keenan says publishers are leaning into bold colours, big type and simple, iconic symbols that still read when a cover’s shrunken to a couple of inches on an app.

The downside is a kind of visual cloning. Philip Gwyn Jones — a former publisher who’s now a literary agent — says Japanese fiction has sometimes been pushed to feature a cat on the cover “even if there wasn’t a major role” for one, because it seemed to help sales. Keenan adds designers are often given “comparable titles” as a not-so-subtle hint to echo whatever’s already working — cosy crime in particular.

Then comes the blurb, written to stop you putting the book down again. A commercial copywriter says you’ve got seconds, and even the structure is tailored to how people scan: readers often move in an “F” pattern, so the punchiest lines need to land early.

And yes, the hype machine reaches beyond the bookshop. Digital marketing director Lee Dibble says influencers are powerful because communities trust them, with Gwyn Jones pointing to Jack Edwards sparking renewed interest in Dostoevsky’s White Nights in 2024, helping it sell more than 100,000 copies. But the persuasion can get awkward: Gwyn Jones describes publishers gathering influencers for dinners, and a publicist says some BookTokers expect payment simply to cover a book — separate from clearly labelled paid partnerships.

Even with prizes, pre-orders and the new world of “generative engine optimisation” for chatbots, one line sums up the gamble, via copywriter Louise Willder quoting screenwriter William Goldman: “Nobody knows anything.”