By Gillian Lacey-Solymar Consumer Affairs Correspondent

A bit of retail therapy is supposed to be good for you.

Strolling round the shops at leisure, trying on items which catch your eye, making those purchases you've been meaning to get for ages.

But who's really making the choices?

You're certainly picking up the bill, but the shops could be having a bigger say than you think.

Men hate shopping so what we have to do is make it as simple and spartan as we can

Tim Denison, Retail Psychologist

We all know how supermarkets waft the smell of baking around the store to entice you in and how soothing muzak can make you linger while brisker tunes are designed to keep you on the move.

These subliminal techniques have been around for a while, but there's evidence that the use of psychology by retailers is growing.

Why else would someone like Tim Denison be in a job?

He's a retail psychologist and he let me in on some of the secrets of the retail sector.

Retail psychologist Tim Denison

The shops are clearly far more sophisticated than you might think.

There's barely one of our senses that doesn't get assaulted the minute we walk through the door.

In fact it can start before then, with warm air over the doorway to lure you in.

Of course, that wouldn't work in hot countries such as Spain. They have their own version with air conditioning at the entrance.

Holiday mood

Smells are still a favourite - travel agents sometimes release a coconut odour to get you in the holiday mood.

Items placed at eye level are supposed to sell better, and the end-of-aisle baskets are best for impulse buys - you spend longer turning corners with awkward trolleys, so they catch your eye.

Then there are the the colours; a red carpet is thought to get you in the right mood for spending, while blue is too much like water, and could make you feel uneasy.

"We tend to spend longer on a red carpet than a blue one," says Tim.

But where the black art is really catching on is in the way it differentiates between women and men.

Tactile

A woman entering a shop might well find tactile clothes, with lots of frills and lush materials, at the front.

"That's a sense which women really do buy into at an early stage," explains Tim.

How women shop: Mmmm... nice material

"The key to effective retailing for women is to make it an engaging experience so what you want is product as close to the shop front as you can."

Items are placed near each other to allow a woman to visualise them together, as an outfit.

Clothes will be grouped not by what they are but their style - classic or casual, for instance.

How men shop: A shirt is a shirt is a shirt

When a man goes shopping it's a different ball game.

He wants to buy a pair of jeans because his old ones have worn out. In fact, he probably wants to get exactly the same jeans.

So menswear shops are much more utilitarian.

Men don't want to be confronted by ideas and subliminal suggestions.

They want everything in its place so they can buy what they want and go - shirts all together here, trousers over there, shoes along there.

Meeting our needs?

"We all know that men hate shopping," says Tim, "so what we have to do is make it as simple and spartan as we can."

Retailers would argue that they're meeting our needs.

In what we often describe as a "cash rich, time poor" society, people want things made easy for them.

That's why Marks & Spencer put strawberries and cream together - to save people the trip between the fruit and the dairy sections.

There's no doubt some of these techniques do work. It's a real science to work out what goes where, with complex financial spreadsheets used to help make the decisions.

But just as the shops are becoming more sophisticated, so are the shoppers.

More theatre and passion

Tim predicts more theatre and passion in shopping, which is fine in principle. Gimmicks are another matter.

If you're househunting and the vendors are trying the old freshly brewed coffee trick, you're likely to get suspicious - we can be quite cynical as a nation.

So while the mind games are targeting our subconscious, they tend to work well.

But if they become too obvious, we're likely to resist, and things can backfire for the retailer.

We don't mind splashing out our hard-earned cash, but we don't want to feel we're being overtly manipulated.