Visitors to Israel from countries with a strong emphasis on customer service are often dismayed by the relative lack of smiles displayed by sales staff in local retail stores. The less effusive Israeli style can seem off-putting to those used to a North American standard.

Now, it turns out, the Israeli way – if not taken too far – may actually be better for business.

Researchers at the University of Haifa and the Open University of Israel, along with the University of Amsterdam, have found that service staff who express emotions in “high intensity” are perceived as less trustworthy and inauthentic by customers. It doesn’t matter whether the interaction is in person, over the phone or by email.

And if the salesperson is over-enthusiastic, customers may be less likely to use the product they buy.

That’s not to say that customer service staff shouldn’t strive to be positive. But “it’s important to pay attention to the magnitude in which the emotion is expressed by service staff,” explained Arik Cheshin of the University of Haifa, one of the authors of the study.

These results contradict previous studies that have found the expression of emotion by service staff has a positive impact on customers. Indeed, offering service “with a smile” has become a truism in much of the sales world.

To find out whether intensity of emotions carries a“social impact,”the Israelis launched a study involving a total of 1,118 participants where a customer was looking for a product.

In some cases, no choice was available and there was only one option for participants, while in others, the specific product was not in stock and the customer was offered another product instead. Sales staff were instructed to add an emotional expression of happiness or sadness at either a low or a high level of intensity.

According to the findings, high-level emotional expression impaired credibility.

In an additional experiment, customer participants were promised a DVD movie matched to their personality and preferred genre. The participants rated 10 different movie genres and took a personality test. A week later, the participants received an announcement of the chosen movie, along with an email message from the service provider which included happiness or sadness at varying levels.

All the participants received the same movie – a Western, which was not a top pick for any of them. But those customers whose salespersons expressed a high level of emotions wound up viewing the movie less than customers whose customer service representative wrote a message with lower emotional intensity.

“It isn’t enough simply to ask or demand that service staff smile at customers or express positive emotions. It is important to emphasize the strength of the emotional display and to make sure that it is appropriate to the situation,” Cheshin concluded.

In other words: It’s okay to smile… just not too much.