You know how it goes: A traffic jam blocks your way to work. A rude driver swerves in front of your car and you spill that just-purchased café latte into your lap. You arrive late, in a lousy mood. From there, the day just goes downhill and your workplace performance falls to pieces.

Or does it? Everyone has bad mornings. But does a bad mood really color one’s entire day and undermine productivity? Some people, after all, thrive on tension; for others, perhaps settling in to work helps them shake off the lousy mood they started with.

“I’m interested in what people bring with them to organizations,” says Wharton management professor Nancy Rothbard. “In my experience, and in the experience of many others, people are not able to completely wall off and compartmentalize different parts of their lives. There is a spillover between the multiple roles that people inhabit.”

A significant amount of research has been done in the past two decades on work-family conflicts, Rothbard notes, “but very few studies have actually looked at the effect [of mood] on performance in the workplace.” Specifically, Rothbard and Steffanie Wilk, a professor at the Fisher School of Business at Ohio State University, wanted to find out which mood-altering events have the biggest effect, if any — those that influence one’s outlook at the start of the day, or those that nudge one’s mood up or down as the workday advances. The results of Rothbard and Wilk’s study of call-center employees at a major insurance company are reported in their paper, “Walking in the Door: Sources and Consequences of Employee Mood on Work Performance.”

The researchers found that both positive and negative moods affect employee productivity, but that positive moods are more potent. Most importantly, they discovered, the mood you bring with you to work has a stronger effect on the day’s mood — and on work performance — than mood changes caused by events in the workplace. This finding, according to Rothbard, suggests that a business’s performance might be enhanced by efforts to help employees cope with mood-affecting influences in their private lives — including advising employees on how to best handle commuting hassles or offering counseling for family problems.

“The fact that start-of-the-day mood has such a strong and consistent effect is pretty powerful,” she says. “It is something that organizations don’t take seriously.”

The Swerving Jerk or the Cranky Customer?

In tackling the effects of mood, Rothbard and Wilk write, their first question was “whether mood on arrival at work influences employee work mood during the day…. Second, we are interested in whether employee work mood is more or less influenced by the moods people start with than by the moods generated from the interactions they have during the rest of the work day.”

In other words, which upsets you more: that swerving jerk on the road, or the cranky customer on the phone?

Rothbard and Wilk wanted to advance other researchers’ findings on forms of “emotional contagion” — occasions when one person’s mood influences another’s “through a process of observation, mimicry, and synchronization.” The two researchers also wanted to sift out any effect from employees’ underlying temperament — the basic mood one tends to have until events change it. By removing this “trait affectivity on workplace outcomes,” they hoped to determine the effect of the more ephemeral mood-changing events.

“Start-of-day mood may come from myriad sources including persistent life challenges and opportunities, positive or negative family experiences before leaving for work, or even the commute into work,” they write. “Non-work and work domains are permeable, and research suggests that mood often spills over from one to the other…. Specifically, start-of-day-mood might affect one’s appraisal of subsequent events.”

Rothbard and Wilk studied employees in call centers operated by a large insurance company on the East and West coasts. The employees included customer service representatives, claims assistants and claims adjusters, as well as their supervisors and managers. The employees completed preliminary questionnaires “to get baseline information on their trait affectivity” — a sense of each one’s basic tendency to be happy, sad and so on. The baseline allowed the researchers to determine how the day’s events changed employees’ moods.

The 29 customer service representatives each fielded an average of 64 calls per day, and spent virtually their entire workday on the phone. By listening in on some of their calls, the researchers found that callers expressed emotions ranging from pleasant to neutral, angry to frustrated, scared to sad.

Over a three-week period, the researchers used questionnaires, which popped up on the reps’ computer screens throughout the day, to sample their moods, as well as the reps’ assessment of customer moods. Typical questionnaires asked for replies, on a scale of 1 to 5, to questions about whether reps started the day feeling excited and enthusiastic, or upset and irritable. At various points during the day they were asked to rate their own moods again, and to gauge those of individual customers — whether they were rude, calm, hostile, insulting, cheerful, friendly or frustrated. At least twice a day the reps answered questions about how well they felt they had focused on the most recent customer call.

In addition, the researchers had access to the performance metrics used by the insurance company to assess the reps’ work. This computerized data gauged factors such as the percentage of time each rep had during the workday to answer calls — in essence, the time they were logged on and not taking breaks. It also counted the number of times each rep transferred a customer call to a supervisor, which was considered undesirable. The number of calls each rep handled per hour was also assessed, with higher numbers considered better.

After controlling for each rep’s underlying temperament, Rothbard and Wilk found that reps who started the day in a good mood tended to stay that way. This was reflected in a strong correlation figure of 0.36 (with 1 being a perfect correlation) between start-of-day positive mood and positive mood during the day. Reps who started the day in a bad mood also tended to stay that way, with a correlation figure of 0.38.

“Start-of-day positive mood spills over and affects positive employee mood during the day,” the researchers found, adding that “likewise, start-of-day negative mood spills over and affects negative employee mood during the day, even accounting for work-related contextual influences like customer interactions.”

While those findings were not particularly surprising, the study uncovered a twist when it focused on how reps reacted to customers’ moods. When reps believed their customers were in good moods, the reps’ moods tended to get better, with a correlation of 0.25. But, the reps’ moods did not tend to fall when they felt their customers were in bad moods. In these cases, the correlation was a mere 0.08.

When the rep’s start-of-day mood was good, and the customer also was in a good mood, the rep’s mood tended to remain good. But when the rep’s starting mood was bad, it did not tend to get worse when the customer was also in a bad mood. Reps with less time on the job tended to be affected more by customers in bad moods. This suggests that negative customer moods have a less potent effect on reps’ moods, or that reps get hardened to unpleasant interactions or leave the firm if they can’t, Rothbard says.

“Overall, the combined analyses suggest that start-of-day mood had a more consistent effect on worker mood during the day than did perceived customer mood, because negative customer mood did not seem to consistently influence employee mood throughout the day,” the researchers conclude.

The survey of worker performance revealed “partial” support for the hypothesis that workers perform better when they are in good moods. Those in good moods had more time to deal with customers, probably because they took fewer breaks. The happier reps also tended to transfer fewer calls. But being in a good mood did not cause them to field more calls per hour.

The effect of negative moods was slightly different. Reps in bad moods handled fewer calls per hour and were less engaged in their jobs. But bad moods did not significantly increase their phone transfers or reduce the time they had available for customers.

What does this boil down to?

“One of our findings shows that the mood people bring with them at the very start of the workday influenced employee mood more powerfully and consistently than any other variable,” Rothbard and Wilk write. “We also found that for the most part, as expected, customer mood influenced employee mood. Interestingly, negative customer interactions only affected less experienced workers. Last, we show that daily mood at work can influence important work outcomes.”

Start-of-day moods may be more potent because they are caused by events that are more important to workers than interactions with customers, the researchers note. It is also possible that workers are trained to handle customer moods but get no similar training on dealing with start-of-day moods. Future research, they suggest, should look at various events that influence those start-of-day moods.

“What I think is really interesting about these findings is that the positive mood that you bring to work is very strong,” Rothbard says. “People actually do a pretty good job of walling off the negatives. What’s interesting for organizations to understand is that what people bring with them to work is not all bad for the organization, and in fact can be quite positive.”