We know what we like ..

As volatile financial markets on both sides of the Atlantic look increasingly troubled, the contemporary-art market seems to be holding up. In the past two months, Sotheby's set a record of more than £95 million for the most successful auction of contemporary art in Europe, and in a Christie's sale of postwar and contemporary art, a Francis Bacon triptych was snapped up for £26.3 million.

The contemporary-art market has been booming over the past ten years. If played right, the art market could have made you more money than the stock market or property. In early 2006, a print by the Bristol-based graffiti artist Banksy sold for just short of £30,000. Six months later, another print from the same series, for Blur's album Think Tank, fetched £300,000.

Big price tags make the contemporary-art market look recession-proof, but how do the sums involved affect our sense of taste?

Figures such as Charles Saatchi, Larry Gagosian and Jay Jopling are perhaps the biggest influence on the contemporary-art market. Their enthusiasm for emerging artists is infectious, with established investors and new collectors alike following their lead. Collectors and dealers influence taste in terms of what they buy, put on show or give to the public domain. Public galleries, institutions and the Turner Prize are never far behind. It is no coincidence that works presented to us at Tate Modern often bear all the hallmarks of trends championed in the marketplace.

In one sense, from the Florence of the Medici or the Amsterdam of Rembrandt to Victorian Britain, none of this is really that new. Nor are the complaints. Sotto voce mutterings about prices being skewed or the biasing of taste can be found wherever markets boom or a few individuals wield huge clout. Patronage and markets just work this way. Money likes being dressed up in the accoutrements of taste. So what? Why think that this has significant implications for taste or aesthetic appreciation?

The trouble is that we think we know why we like the art we do. Yet a lot of the time all sorts of subconscious factors from status cues to subliminal recognition influence our appreciation and judgment.

Scientists from Stanford University and the California Institute of Technology recently conducted a distinctive wine tasting. People were asked to sample cabernet sauvignons and were told the supposed price (from $5 to $90, £2.50 to £45) of each one. Unsurprisingly, the more expensive the wine, the better subjects reported it tasting.

The experiment was based on Frederic Brochet's infamous wine experiments from a few years ago. Brochet decanted a white wine into two glasses and dyed one red with tasteless food colouring. Wine experts were invited to give their appraisals of each one. No one spotted the similarity. In another experiment, Brochet decanted a middle-of-the-road Bordeaux wine into a fancy grand-cru bottle and a plonk bottle. The descriptions and appraisals of the wine experts diverged hugely according to the different bottles. Out of 57 wine experts, 40 said that the wine from the grand-cru bottle was worth drinking but only 12 said that the wine from the ordinary bottle was. It was the same wine.

The Stanford-Caltech experiment added another dimension. Subjects were put inside a scanner so that the experimenters could see how people's brains were responding. Whenever someone was told that the taste was from a pricier wine, even when it was not, part of the brain involved in experiencing pleasure suddenly became more active.

What this suggests is the significance of expectation. If we know that something cost a lot of money not only do we expect it to be better, we are more inclined to think it is better. We experience and value it as such. The status cue, and not just the actual taste of the wine, influences the pleasure and appreciation taken in the wine.

The experiment could have been performed on anything from contemporary art to fashion. But it is not just financial status cues that have this effect. In an experiment at Cornell University, James Cutting used commonly and rarely reproduced Impressionist paintings as slide backgrounds while teaching an introduction to psychology course. He first established that students preferred more frequently reproduced images, even though they could not recall having seen them before, over more rarely reproduced ones. Then, throughout the course, Cutting used rarely seen works as backgrounds more often than those commonly reproduced. At the end of the course, he asked students to rate a bunch of Impressionist works. Even though students had no reliable recall of whether or not they had seen the works before, they showed a marked preference for those that had been used most frequently over the course.

Even without conscious recognition, familiarity produces an increased positive effect. We might not realise that we've seen or heard of something before, and yet subconscious recognition seems to trigger greater pleasure and deceive us into thinking that we are enjoying something more because it is highly valuable - rather than just because we have come across it in the news, an arts magazine, a glossy art history book or even on some friend's mug.

Why are our tastes so susceptible to such influences? One possible explanation is that art and art appreciation evolved as an indication of fitness with respect to creativity and mental adaptivity or in ornamental terms as an indicator of high status. Prizing both the aesthetically highly esteemed and the familiar could be an upshot of an evolutionary function that helps ensure reproductive success. Signalling appreciation of such things might enhance one's chances of getting laid. Still, this all seems rather speculative.

Luckily, there is a more determinate social psychological explanation. We define ourselves from an extremely early age through our relations with others. Our drive for social status is commonly realised through representing ourselves as superior to other individuals or groups, especially in individualistic societies where competition and self-expression are central. Hence we are prone to being easily influenced by factors that enable us to appear more knowledgeable or sophisticated than we really are.

The thing about taste is that it is so much easier to kid yourself or others that you are getting things right - that the pleasures of recognition or status really are the pleasures of refined appreciation. Start trying to appear superior about mathematics or etiquette and you'll be easily shown up if you get things wrong. Do it with wine or art and, well, who knows?

Traditionally, we assume that we know when and why we're making the aesthetic judgments we do. It is the taste of the wine or the look of the painting. But if the science is sound, then this is not quite right. It can be extremely difficult to tell why we like something since we are often pushed one way or another by situational cues that we're not even aware of.

It is tempting to think that tricks our minds play on us simply distort aesthetic appreciation. True, we should be wary of assuming that high prices in contemporary-art markets are an infallible indicator of artistic value - today's "genius" may be tomorrow's dunce. We need only look back to the Victorian art-market hysteria to see that fashionable pricey art can end up seeming pretty mediocre. Edwin Long's Babylonian Marriage Market sold at Christie's in 1882 for a record-setting 6,300 guineas, but we hear little about him now. Why indeed should we? His huge, laboured, static canvases of biblical scenes are hardly compelling. Yet this cannot be the full story.

As philosopher David Hume recognised, our tastes can be more or less well developed. Whether it is wine or art, individuals can be better or worse at discriminating between elements of experience and why they are valuable. If someone describes the wine you are drinking as grainy, you suddenly sense its coarse texture and become sensitive to it in other wines you have tasted before. Someone describes why Vermeer's Little Street embodies a sense of unknown interior life and then unexpectedly you get the point of Gillian Wearing's photo of a City slicker holding up a placard proclaiming "I'm Desperate". Aesthetic expertise is hardly a myth.

Those influencing the art market take a huge interest in and know a lot about contemporary art. Thus, the marketplace should be some kind of rough indicator of artistic worth. It may overinflate estimations or overlook artists, but it is often on to something. It is no surprise that in 17th-century Amsterdam, Rembrandt was one of the most popular and expensive contemporary artists. The market may be far from infallible, but it is far from worthless. The high cost of a bottle of wine or a record price for Bacon's work is grossly simplistic as a ranking of aesthetic value, but it may be enough to indicate that the wine is worth tasting or the work is worth looking at.

Aesthetic expertise is not a fraud, and money or fame does not automatically corrupt judgment. What the experiments suggest, however, is that aesthetic knowledge is much more fragile than we presume - something worth bearing in mind when talking about the next exhibition or bottle of wine.