IT IS an odd sight. A middle-aged man, fully reclined, drawing pictures of hammers and mugs and animal figurines on a special clipboard, which is balanced precariously on a pillow atop his ample stomach.

A half-dozen people buzz around him. One adjusts a towel under his neck to make him more comfortable, another wields a stopwatch and chants instructions to start doing this or stop doing that, and yet another translates everything into Turkish. A small group convenes in a corner to assess the proceedings. A few of us just stand around watching, and trying not to get in the way. The elaborate ritual is a practice run for an upcoming brain scan and the researchers want to get everything just right. Meanwhile, the man at the centre of all this attention, a blind painter, cracks jokes that keep everyone tittering.

The painter is Esref Armagan. And he is here in Boston to see if a peek inside his brain can explain how a man who has never seen can paint pictures that the sighted easily recognise – and even admire. He paints houses and mountains and lakes and faces and butterflies, but he’s never seen any of these things. He depicts colour, shadow and perspective, but it is not clear how he could have witnessed these things either. How does he do it?

Because if Armagan can represent images in the same way a sighted person can, it raises big questions not only about how our brains construct mental images, but also about the role those images play in seeing. Do we build up mental images using just our eyes …