While consumers generally believe that they are good judges of their own preferences, two new studies out of the Yale School of Management suggest that, counterintuitively, individuals have a poor understanding of what motivates certain purchases.

In one of the studies, researchers found that associating guilt with the consumption of a hedonic object like a candy bar actually increased the pleasure the individual got from the experience. The other study found that consumers actually perceive two items as more similar when the prices were slightly different rather than the same. The two findings, which are scheduled to be published in the coming months, have implications both for the way consumers think about purchases and how marketers brand their products, said Ravi Dhar, a professor of management and marketing at the Yale School of Management who was a co-author on both papers.

Subjects in the study on guilt were primed with the concept of guilt by unscrambling words associated with the emotion. Those individuals reported enjoying a variety of indulgent activities, from consuming candies to browsing online dating profiles, more than the individuals in the control condition who had unscrambled neutral words.

“Guilt has the unique effect on pleasure specifically because the consumer maintain a cognitive association between guilt and pleasure, which is to say that when we think about guilt, we often think about pleasures that is associated with guilt,” said Kelly Goldsmith SOM ‘09, study co-author and professor of marketing at the Kellogg School of Management at Northwestern University.

Goldsmith worked on the study with Dhar when she was a doctoral candidate at Yale.

Both Dhar and Goldsmith said that the findings have implications for the way firms market indulgent items. While some companies encourage consumers to buy indulgent items by minimizing the feelings of guilt associated with purchase, this finding suggests that companies should do the opposite.

“If you have an online dating website and you want to provide consumers online with an experience that is maximally pleasurable, we would argue that letting them feel a little bit guilty and a little bit naughty searching around on those online ads is perfectly OK,” Goldsmith said.

The inspiration for the study on guilt arose anecdotally, when one of the administrative assistants at the School of Management complained how difficult it was to adhere to her diet when chocolate tasted so good, Goldsmith said. While people generally believe that people enjoy experiences less when plagued by feelings of guilt, Goldsmith said she was intrigued by the possibility of a reverse relationship.

Juliano Laran, an assistant professor of marketing at the School of Business Administration at the University of Miami who was not involved in the study, said that the finding is “an amazing piece of research,” in part because it is one of the few to show that a negative emotion like guilt can have a positive effect.

While the study on guilt looked at the influence of the emotion on pleasure, the paper on perception of similarity probed the connection between small variations in products and, ultimately, the consumers’ willingness to purchase the items.

In one part of the study, subjects were asked to rate the similarity of two types of tea. In one condition, the products had equal prices, while in another, the prices were slightly different. The team found that individuals rated the teas as seeming more similar when the prices were different.

Nathan Novemsky, study co-author and professor of marketing at the Yale School of Management, said people sense more difference as overall similarity because identical characteristics, like equal price, drop out of consideration and consumers are left to focus on the more salient differences, like tea flavor, that remain.

“When you are focused on an attribute that is actually quite similar like $3.68 verses $3.73 for price, you start thinking, ‘Well these teas are kind of similar,’” Novemsky said. “The similarity of price bleeds over to a global similarity between the two items.”

While the finding is surprising and interesting on theoretical grounds, it becomes important in practice when extended to purchase incidence, Novemsky said. Dhar had found in a previous study that when individuals perceive two items as more similar, they are more likely to purchase one because of decreased anticipated “buyer’s remorse,” according to Novemsky.

Indeed, Novemsky and Dhar found in the study that slightly varied prices did make individuals less likely to defer purchase.

Companies have historically believed that pricing similar items at the same price makes it easier for consumers to chose which one to buy, Novemsky said, and the study suggests that this intuition is mistaken.

Gal Zauberman, a professor of marketing at the Wharton School of the University of Pennsylvania, said that he would like to see the research team explore what other attributes, apart from price, apply to the phenomenon. He said that he suspects small differences in quantitative attributes will have more of an effect on global perceptions of similarity than manipulations of qualitative components.

“[The] difference between blue and red is not the same as between $1.50 and $1.60,” he said. “It will be nice to see them expand it later.”

Dhar said the studies on guilt and similarity suggest that for those interested in knowing consumers’ preferences, asking the buyers themselves may be misleading.

Indeed, asking consumers to describe how they would respond to certain situations is the most common way for firms to conduct consumer research, Dhar said, but these studies contribute to a growing body of research questioning that method.

“People don’t necessarily have proper intuitions about how they would behave in a certain situation,” he said.

Dhar is the director and co-founder of the Center for Consumer Insights at the Yale School of Management.