The scent of fresh pine, Christmas music, cheerful sales associates wearing Santa hats. The holiday shopping season has officially begun. But don’t be fooled: The wintry wonderland in most retail stores is carefully crafted to get you to spend big.

As shoppers chase holiday-season deals, they may not realize all the subtle ways retailers are hunting them. From wafting fragrances to salespeople who lightly touch customers, retail companies use a bevy of psychological tricks to play on consumers’ most basic urges -- and generate sales.

During the holiday season, two of the more common sales-driving tactics retailers use are scarcity (as in, “while supplies last”) and delayed cost, which manifests itself in offers that claim “no money down and zero interest until 2016.” Other methods of enticing consumers include free trial periods and customization offers, common with cell phones, for example. Both give the customer a greater feeling of control, experts say.

In a retailer’s ideal scenario, a shopper approaches a store aisle, calmly searching for what he or she wants. Then, after finding the item quickly — say, a throw pillow — picks it up, turns it over, examines the seams, and tests its sturdiness.

“If you can get people to touch a product, even the packaging, then the person feels more ownership, and whenever you feel more ownership, you’re willing to pay more,” said Joann Peck, marketing professor at the associate dean of undergraduates at University of Wisconsin-Madison’s business school. “As a consumer, you should be very careful what you reach out and touch.”

Carl Marci, co-founder of Innerscope, a Boston-based consumer neuroscience company, and former head of neuroscience at Harvard Medical School, studies how people make decisions to optimize advertising and help retailers raise revenues. Often that means helping shoppers find what they’re looking for more quickly with massive signs and shelf placement techniques like color-blocking, grouping items of like color next to each other, to attract gazes.

“This time of year, they’re going to shift items people tend to purchase to more prominent locations,” Marci said. “They try to trigger what [shoppers are] already thinking and get them to explore a bit. Items that you know people are going to buy are placed next to items they might buy with higher margins.”

Placing items like chocolates and candies in unexpected places can facilitate impulse purchasing, though these sales are difficult for retailers to snag on purpose. The best defense against an impulse purchase is to plan which items to buy and do your research before entering a store.

Visual aids are only one method. Home Depot has wafted the scent of freshly cut grass in lawn departments to entice shoppers, and some retailers such as Wal-Mart play to all five senses. The aromas of fresh foods and baked goods like pumpkin pies stimulate appetites, and holiday music plays as a constant reminder of the gift-buying season. The retail giant's stores feature free samples of snacks sold nearby and product placements on shelves at eye- and arm-level encourage shoppers to reach out and touch the product.

While touching a product creates a sense of ownership, encouraging the shopper to buy, stimulating the other senses plays on the shopper's mood. Holiday lights and bows, popular tunes like Jingle Bells that many associate with positive memories, and familiar scents like roasting turkey all create a positive shopping experience designed to get shoppers into a gift-buying mood.

"The trick is to use queues in the store to remind people the holidays are here," Marci said. "It’s designed to put you in the holiday spirit and remind you that you should buy gifts."

And if a friendly salesperson guides shoppers with a personal touch to the right aisle or shelf, sales are likely to increase. Peck’s research shows that when a salesperson lightly touches a customer’s arm, it’s “super helpful” in influencing one-quarter of customers to buy, regardless of gender combinations. Any positive experience a shopper has in the store, anything that improves his or her mood, will add to the likelihood that he or she will buy, Marci said. The light touching discourages only 10 percent of shoppers from buying.

“There hasn’t been a lot of research done on interpersonal touching, but the benefits really seem to outweigh the costs,” Peck said.

With so many psychological prods, shoppers may think their best defense is learning to say no. Actually, experts say, the best defense is cultivating gratitude. David DeSteno, a psychology professor at Northeastern University, suggests that the most effective way to fight temptations to buy something you don’t need is to recall what you’re thankful for. In other words, celebrate Thanksgiving the traditional, noncommercial way.