It’s an exhibition that inevitably provokes the “I could have done that” school of art criticism. A bunch of old fluorescent tubes stuck on the wall? What’s the point of all that anyway? Personally I would defy anyone not to feel something inexplicably affecting about the light sculptures created by the American minimalist Dan Flavin, currently the subject of a retrospective at the Hayward Gallery, London. But neuroscientists are now producing more objective evidence that there’s a great deal of point to Flavin’s work — putting their fingers on how line, light and colour act on the brain — to move, stimulate or sometimes plain poleaxe us.

Dr Mark Lythgoe, a neurophysicist, has concluded that Flavin’s work taps into some basic brain responses that have their roots in our early evolution. We’re programmed to react in a particular way to light, line and colour — it goes back to our earliest survival instincts. Creatures with brains that had adapted to distinguish differences between form and illusion, light and shadow, movement and immobility, are most likely to be able to elude predators and find food. Natural selection means that the human race holds these deep-rooted tools in common. And Flavin, an American who emerged in the New York art scene in the 1960s and died in 1996, taps into them.

Dr Lythgoe, from the Institute of Child Health at University College London, stops me in front of a construction glowing a remarkably rich red — Monument 4 for those who have been killed in ambush (to P.K. who reminded me about death), 1966. He believes it plays on our most basic fight or flight instincts. “Red is incredibly stimulating to the brain, which is why it can be so effectively used by artists. It goes back to our evolutionary past, when red indicated ripeness of fruit. Way back, we also became programmed to flee the colour red because it was used as a warning signal by some animals, for example apes and fish.” That neurological remnant remains etched in our brains, Dr Lythgoe maintains.

So when I can’t help uttering a “wow” in the face of the all-embracing green created by Untitled (to you, Heiner, with admiration and affection), 1973, Dr Lythgoe reminds me that my response is a vestige of my ancestors’ sensitivity to green — they needed to be able to distinguish different shades of the colour under tree canopies if they were to find food and avoid enemies.

Dr Lythgoe specialises in using brain scans to analyse which parts of the brain are active under which stimuli. With a team of scientists from University College London and King’s College London, he was called in by the Hayward Gallery to analyse Flavin’s work in the context of current knowledge about how the brain works.

We now know from magnetic resonance imaging of the brain, for example, that light has a generalised effect throughout the brain — as seasonal affective disorder (SAD) indicates, it affects our brain chemistry and mood. But we process other visual information, such as line, colour and faces, in very specific areas of the brain. Brain scanning has now revealed that just one tiny part of the brain — known as V4 — is responsible for colour. So localised is the “colour” area of the brain that people with a head injury affecting only this part of it suddenly start seeing in black and white, with no other symptoms.

Line, too, is processed in one particular part of the visual cortex. “Studies have shown that the brain is very sensitive to line orientation — as the angle of a line it sees changes, so does the firing rate of neurones,” says Dr Lythgoe. He stops me in front of one of Flavin’s earliest, simplest creations — The Diagonal of May 25, 1963 (to Constantin Brancusi), 1963 — a single yellowy-white illuminated tube at an angle of around 45 degrees from the floor. He says its positioning is far from random.

“I think Flavin would have played for hours with length and angle to get a certain effect that felt right. I think he had something of the neurobiologist in him — though without putting electrodes into the brain to see which parts lit up. He, like all artists, knew something was happening instinctively. It taps into something that was, in evolutionary terms, very important to us.”

This instinctively scientific approach can produce some magical effects, particularly when it comes to the way that the brain processes colour. (See caption, below, for Untitled (to Jan and Ron Greenberg), 1972-73.) As we exit from a room swathed in fluorescent green light out into the foyer of the Hayward, the white world beyond has been miraculously transformed to a delicate shade of lilac-pink — an optical hangover after the brain has been thinking green. I am left seeing the world through rose-tinted spectacles. And it’s a very nice view indeed.

“What Flavin did,” says Dr Lythgoe, “was to tap into feelings and visual effects that we all share — and I think that’s probably what art is. It’s seemingly quite academic art and quite hardcore but you don’t have to go much below the surface to see where it is really coming from.”