It used to be that if you wanted your dinner guests to indulge in a bit of heated debate and conversation over their chilli and red wine, you painted the walls of your dining room red.

Colour psychologists will tell you that red has been associated with danger, passion, energy, warmth, adventure and optimism ever since Stone Age man first realised that deep red berries were poisonous.

Now that every Tom, Dick and Harry's dining room is painted red, though, restaurants have moved on to newer, more esoteric ways of triggering lively conversation among their diners. Namely, with expensive - and sometimes controversial - works of art. This move reveals a lot about the often unappreciated relationship that exists between many chefs and artists.

Take, for example, the new water nymphs that adorn the walls of Roy Brett's award-winning seafood restaurant Ondine in Edinburgh. Painted by the contemporary Edinburgh artist Davy Macdonald, the bare-breasted creatures meet you as you walk up stairs and watch as you eat (or invite you to watch them). They're set in gorgeously fancy frames and emanate the still-blue calmness of the sea from which they, and the seafood itself, come. Their arrival in Edinburgh's douce Old Town is a bold move; according to Brett, they have prompted much welcome discussion among his clientele.

The chef explains that art can create another talking point that is nothing to do with the food; yet it can enrich the eating experience, fill lulls in conversation or service, and encourage us to look at and think about the world in new ways.

But there's another element: the stories behind the paintings themselves. Just ask any chef and they'll wax lyrical about why they like their paintings, how they acquired them, the story of the painter's life and how they first encountered each other. Very often, as in Brett's case, the art is on loan or for sale.

The link between food and art isn't new, of course. The London chef Mark Hix has had a long association with the artists Tracey Emin, Damien Hirst and Sarah Lucas, whose work hangs or is exhibited in his restaurants. He doesn't necessarily buy the art; he does exchanges. The artists eat there and bring their interesting friends, and he gets their artworks to "have a nice story on the walls" that can be seen by more ordinary people than seasoned gallery groupies.

This payment-in-kind idea was the basis for the relationship between the late Glasgow restaurateur Ronnie Clydesdale and the artist Alasdair Gray: for creating the distinctive 1970s murals on the walls of the Ubiquitous Chip that still exist over 40 years on, Gray got to eat for free.

Brian Maule's Le Chardon d'Or in Glasgow has around 20 paintings by living Scottish artists on loan from the Roger Billcliffe Gallery, and while some are purchased they help showcase the artists to a different audience as an extension of the gallery. They are predominantly colourful flowers and landscapes by Christine McArthur; her more humorous paintings continue to provoke comment. The chef says he's not an art buff but knows that the paintings create an ambience and warm the place up.

The famous Glasgow restaurateur Ken McCulloch, founder of One Devonshire Gardens in Glasgow and the Malmaison chain, and owner of the Dakota hotels in South Queensferry and Glasgow, deserves credit for setting this precedent. Dakota hotels showcase work by emerging painters from Edinburgh College of Art. Selected in a competition with £1000 prize money for each student, the works are shown for three to four months at a time.

But it was while speaking with Andrew Fairlie about his love of Archie Forrest's portraits and still lifes, which originated at One Devonshire Gardens and now hang in his double Michelin starred restaurant at Gleneagles, that I really understood the connection. Fairlie told me that it was Archie's still life compositions that helped him understand the importance of presentation on the plate. "He'd explain why putting a red apple in the corner of a painting only takes the eye away from the action in the centre, and the same goes for how you construct a dish. I learned a lot through him," he told me.

Equally, artists seem to recognise something of themselves in the sheer graft involved in cheffing. Forrest was so intrigued by watching Fairlie that he asked if he could paint him before and after work, while he was still in Glasgow. Fairlie was up for it, and had the paintings hung at his new eponymous gaff. Their friendship continues to this day.

As one chef put it, you can't change what people enjoy eating, but you can enhance the environment in which they enjoy it.

The thing about art is that it's naturally subjective; not everyone will love what you do. But perhaps that's the point. I for one would much rather gaze upon works that are aesthetically challenging or controversial in their subject matter as I'm swigging my oysters. Looking at stuff that's bland and safe just makes me want to go home, and reflects badly on the food.

It is said that we eat first with our eyes. So next time you're eating out, have a swatch at what's on the walls. It really puts chef in the frame.