What do Beethoven, birthday cake and the way your eyes move have in common? They're all conspiring to get you to spend more money when you eat out. While we are all prepared to splash out in restaurants, it's become clearer that restaurateurs have devised crafty ways to make sure we spend more than we had planned to. And while it might not seem unacceptable to charge corkage for when you bring your own wine to an eatery, there are now a number of London restaurants who charge cakeage fees - a sum to serve diners birthday cake - which can sometimes come up to £9 per person. Scroll down for video . Stung by your bill? Restaurants have devised sneaky ways to make diners pay more when they eat out . Not so happy birthday: London eateries are now charging 'cakeage' where diners have to pay to be served birthday cake . From using hyperbole to convince you to order pricier items to drawing your eye to parts of the menu they want you to look at, eateries have devised intelligent ways to ensure that you end up spending more than you planned to. Playing with numbers and omitting dollar and pound signs . Restaurant menus tend to attach prices that end with the number nine to dishes  as it indicates a bargain is being had. For example, a diner would be willing to pay for a dish that costs £19.99 then they would for something which is marked as £20. According to the New York Times, prices which end with .95 instead of .99 are even more conducive to making people spend as they 'feel friendlier' to diners. The publication reported: 'In the world of menu engineering and pricing, a dollar sign is pretty much the worst thing you can put on a menu.' Gregg Rep, a menu consultant in California said to news.com.au: 'Dollar signs remind people of money. When you use dollar signs, your food looks more expensive.' A study by Cornell University's Centre for Hospitality Research, US, found that when dollar signs were left off a menu, sales increased by eight per cent. Kaspar's Seafood Bar & Grill in London's Savoy Hotel (pictured) charges £9 per person for birthday cake . Anchoring . Another key trick is known as 'anchoring'. This is where a restaurant places a highly expensive dish prominently on the menu — solely in order to make the other dishes nearby appear relatively cheap. So the next time you see a £70 steak, look at the item below it, which will seem like a bargain when you compare prices. William Poundstone, author of Priceless: The Myth Of Fair Value Restaurants said: 'Restaurants do not expect to sell many of these costly 'anchor' items. That is not their job — instead they are simply there to make the other dishes look like good value.' Suddenly spending £21 on a plate of lemon sole doesn't seem so outlandish. Identifying body and eye language . Korean studies have shown that diners take an average of 109 seconds to read a menu. So menu consultants have a limited time to make their sell to us, which is why more expensive items of food are always place on the top right hand corner of the page (this is where the eye naturally falls when we look at a page). The most profitable dishes are usually placed there. This subliminal messaging also works in most printed matter, such as newspapers and magazines. Menu boards which omit prices (left) and classical music such as works by Beethoven (right) are some of the ways restaurants make diners pay more for their experience . Tests,which were carried out over three weeks by University of Leicester researchers, monitored the effects of classical, pop music and background silence on spending. They found that when subtle classical melodies were played, diners spent more than £24 per head on average on food and drinks. When pop music was played, less than £22 was spent by each diner and without any background music the spending fell to only £21.70 per head. In the same test, diners were spending over £1 each on coffee with classical music, compared to only 80p with pop music and 54p without any background noise. James Davis, proprietor of Softleys restaurant in Market Bosworth, where the research was carried out, said: 'The sort of music you play does affect people's mood. 'It is quite amazing how much it sets and creates an atmosphere in the restaurant. Sometimes you play what you personally like rather than what the clients like, so I think this research will definitely affect what we play in the future.' Overblown descriptive language . How much would you pay for a chicken nugget? We reckon not more than £2 at most. But what if you were presented with homemade chicken goujuns in a sesame seed crumb dusted with paprika powder and Himalayan sea salt? Then you might be more inclined to fork out in excess of £7 for what is essentially a jazzed-up McDonald's favourite. The language used when writing a menu indicates the exclusiveness of the dish. This is why we now are now seeing incidences of heirloom vegetables, heritage potatoes and artisan breads popping up in every menu. Sauce is now jus or froth, potatoes are 'lightly crushed' and salad dressing is 'tenderly forked through'. Professor Charles Spence, a psychologist at Oxford University, the co-author of The Perfect Meal: The Multisensory Science Of Food And Dining said: 'There's research that demonstrates that if you give food a more descriptive label, people will enjoy it more — and they'll also pay more for it.' One common example of this is to attach somebody's name to a dish. For instance a lot of restaurants have dishes that include the name of the butchers or suppliers, which makes it seem like the dish has been carefully chosen– and thus justifying the price hike. Manipulation through music . While music may well be the food of love, Mozart, Bach and Beethoven could also burn a nasty hole in your pocket, research has suggested. Scientists have discovered that classical music makes restaurant diners feel more affluent and encourages them to spend more money. The less sophisticated tones of Britney Spears as background music saw people typically spending around 10 per cent less on their meals. Researchers at the University of Leicester found that classical music, often associated with affluence, was the most successful in encouraging people to part with their cash. When no music was played, the amount of money spent by diners was dramatically less. Dr Adrian North, senior lecturer in psychology at the university, said: 'When you hear a piece of music it activates all types of knowledge. If you hear classical music, it has got all sorts of connotations of sophistication, affluence and wealth and it makes you feel a bit posh. 'In a restaurant, this has the effect of making you spend a bit more money. Where people were really spending the money was on the luxury items, such as starters, desserts and coffees.' Cakegate . While corkage fees have become the norm, there is now a trend to charge diners 'cakeage' for when they bring in their birthday cake. Prices can go up to as much as £9 per person at Kaspar's Seafood Bar & Grill in London's Savoy Hotel, which is the same price at dessert. Duck & Waffle in London, charges £7 per person serving charge although their staff inform punters that they can provide a cake if you would rather that. Fork out £45 for a medium or £65 for a large cake, depending on the size of your group. Other restaurants charging cakeage include Gordon Ramsay's Savoy Grill and Maze restaurants in London, which demand £5 a head, and barbecue chain Bodean's, charging £1.50. But some restaurants are still keen not to spoil the party. Chain restaurants including Pizza Express, Byron, Wagamama, Wahaca, Jamie's Italian, Carluccio's and Nando's do not charge diners for bringing their own cake. Claridge's bar in Mayfair does not charge cakeage 'as long as it's not a five-tier cake that has to be wheeled in on a horse'.
Tricks include using only numbers to indicate price of dishes . London eateries introduced a per person charge for serving cake . Classical music in a restaurant will make you order more expensive food .