Those who fall part of the latter group have what is known as “aphantasia,” a phenomenon where the mind lacks the ability to conjure mental images. While many effortlessly visualize scenes ...

But Ed Catmull, 74, has the condition aphantasia, in which people cannot visualise mental images at all. And in a surprising survey of his former employees, so do some of the world's best animators.

For most of us that's a natural and easy thing to do. But if you have aphantasia you'd find that very difficult, probably even impossible. The condition didn’t even have a name until 2015 ...