Consumers have a bias against sponsored links that businesses pay search engines to provide, US researchers have claimed.

Jim Jansen, assistant professor in the Penn State School of Information Sciences and Technology, said that businesses spent an estimated $8bn to sell their products and services via sponsored links in 2004, despite little evidence that such advertising successfully directs traffic to websites.

"By themselves, sponsored links appear not to be a viable business model and should be only one part of an online advertising campaign," he said.

More likely to hook consumers are the organic results or those results returned automatically by the algorithmic operations of the search engine, according to Jansen's research paper, co-authored with Marc Resnick, associate professor of industrial and systems engineering at Florida International University.

For the study, 56 participants from 18 to 29 years old - the demographic most targeted by marketers - evaluated the results from 330 e-commerce result queries submitted to a major search engine.

The researchers created a fictitious search engine to display one page of the results from the queries that ranged from looking for information on a class of products, to looking for information on a product in a specific geographical location.

Each participant reviewed six results pages. To measure the appeal of sponsored links, the researchers flipped sponsored links and organic results on half of the pages. This meant that study participants who thought they were evaluating organic links were sometimes viewing sponsored links and vice versa.

The researchers found that on more than 80 per cent of the searches, study participants went first to the results identified as 'organic'. Sponsored links were viewed first only six percent of the time.

"Prior research had noted a bias against sponsored links, but the question remaining was whether sponsored links were as good as organic links," said Jansen.

"What our study shows is that, even when the returned results are exactly the same, people still view what they thought of as the organic results as better."

The quality of the sponsored links was not found to be an issue, according to Jansen, who maintained that the problem lies with the placement of the results.

While study participants rated 52 per cent of the organic results as 'relevant', searchers described 42 per cent of sponsored links as 'relevant' even though both sets of results were identical. That 10 per cent spread reflects a significant degree of bias against sponsored links, said Jansen.

To make sponsored links a viable business model, search engines need to educate consumers, many of whom do not know what sponsored links are or how they appear on a page. Until then, the researchers recommend that businesses make sure that their websites appear high in organic results as well.

"For paid searching to be a sustainable revenue model, search engines and e-commerce organisations have to address consumers' negative bias against sponsored results," said Jansen.