Here's what he has to say in a Paris Review interview called "Completely Without Dignity." This section recalls Kerouac's famous dictum, "Don't think of words when you stop but to see picture better."
Writing is recalling. In this matter I am a classic Proustian. You’re playing football for the first time in twenty years, for example, doing all those movements again, and it makes the body remember not only the strangely familiar movements, but also everything connected to playing football, and for some seconds, a whole world is brought back to you. Where did it come from? I think that all our ages, all our experiences are kept in us, all we need is a reminder of something, and then something else is released.
When I started the novel, I imagined our house, myself walking towards it, it was snowing, it was dark, inside was my father and my mother, and I remembered the feeling of snow, and the smell of it, and the feelings I had toward my father at that time, and toward my mother, and there was the cat crossing the road, and on the other side of the river, the lights from a car. The silence in the woods. My friend, Jan Vidar, he was there somewhere, and the girl I was mad about, and the way I thought of him and her, and the light from the window kind of glowed, and I remembered an episode from the ski slope, and opened the door, and there, on the floor, the shoes from that time, the smell, the atmosphere.
My memory is basically visual, that’s what I remember, rooms and landscapes. What I do not remember are what the people in these room were telling me. I never see letters or sentences when I write or read, but only the images they produce. The interesting thing is that the process of writing fiction is exactly the same for me, the only difference is that these landscapes are imaginary. These images are related to the way you think of a place you never have been, where you imagine everything, the houses, the mountains, the marketplaces. Then, the second you are there and see how the place really is, the weight of its reality crushes your imagined version. But where did that version come from in the first place?