Patti Smylie, Realtor® ReMax Accord Tri Valley

By SANETTE TANAKA

Everyone loves the smell of freshly baked cookies, but don’t expect that aroma to sell your home, new research suggests.

Homeowners are often coached to create pleasing aromas when potential buyers pay a visit. But complex smells, like baked goods and potpourri, are likely to damp enthusiasm for a fast sale for top dollar, says Eric Spangenberg, dean of the college of business at Washington State University, whose study on the effects of aromas is scheduled to appear in the Journal of Retailing next month.

He and his co-authors studied 402 people in a home-décor store in Switzerland over 18 days in 2010 and found that shoppers spent 31.8% more, on average, when the store was scented with a simple orange scent over a complex blend of orange, basil and green tea. The same principles apply to open houses, Prof. Spangenberg says, because in both cases, the aromas may affect cognitive functions in the same areas of the brain involved in decision-making.

Complex scents, even if they’re pleasant, can be a distraction because some people subconsciously dedicate time and energy to figuring out what the aroma is. At open houses, “they are not there to process the smells. They are there to process whether this is a place they want to live,” Prof. Spangenberg says. Instead, he recommends simple scents, such as lemon, basil and pine, since they’re easier to process and less distracting and thus more conducive to spending.

Scents also need to be congruent with the home. A cedar smell might work with a mountain home, but it could seem out of place at a beach house, he says. “You need to think, ‘What scent will buyers associate with this environment?’ It must be simple and positive and congruent,” he says.

Still, many real-estate agents will continue to fire up the oven or light a few candles on open-house day.

“They always tell you to take a bunch of cookie dough and shove it in the oven, so long as it doesn’t burn,” says Adorna Occhialini Carroll, a real-estate agent in Berlin, Conn. Ms. Carroll, who is also president of real-estate training and consulting firm Dynamic Directions Inc., is a big believer in baked goods. “I like pumpkin pie, butter cookies, anything that has that combination of spices and gives you the impression of being at home,” she says.

Chris McDonnell, a real-estate agent with Coldwell Banker Distinctive Properties in Vail, Colo., believes his strategy hits it on the nose. Mr. McDonnell spends up to an hour and a half preparing a home for an open house, cutting fresh pine branches or picking fresh lavender and mint from his herb garden. He looks for scents that mimic the outdoor lifestyle he’s trying to sell. “I never use artificial scents,” he says. “Those candles and sprays are bogus. You want all-natural, all-organic.”

Write to Sanette Tanaka at sanette.tanaka@wsj.com