Moods change how you think: A good mood is a mixed blessing and bad moods have a silver lining.

From a Wall Street Journal story by Daniel Kahneman, Oliver Sibony, and Cass R. Sunstein headlined “Good Moods Often Lead to Bad Judgments”:

We’ve all noticed that our own judgments can depend on how we feel—and we are certainly aware that the judgments of others vary with their moods, too….

The effect of moods on judgment has been the subject of a vast amount of psychological research. It is remarkably easy to make people temporarily happy or sad and to measure the variability of their judgments and decisions after these moods have been induced….

In other words, mood has a measurable influence on what you think: what you notice in your environment, what you retrieve from your memory, how you make sense of these signals.

But mood has another, more surprising effect: It also changes how you think. And here the effects are not those you might imagine. Being in a good mood is a mixed blessing, and bad moods have a silver lining. The costs and benefits of different moods are situation-specific.

In a negotiation situation, for instance, a good mood helps. People in a good mood are more cooperative and elicit reciprocation. They tend to end up with better results than do unhappy negotiators. Of course, successful negotiations make people happy, too, but in these experiments, the mood isn’t caused by what is going on in the negotiation; it is induced before people negotiate. Also, negotiators who shift from a good mood to an angry one during the negotiation often achieve good results—something to remember when you’re facing a stubborn counterpart.

On the other hand, a good mood makes us more likely to accept our first impressions as true without challenging them….

These findings suggest that the moment-to-moment variability of mood affects the quality of our judgments in ways that we cannot possibly hope to control. This variability or “noise” should give a pause to anyone who thinks we can make purely objective judgments. If our mind is a measuring instrument, it is a noisy one.
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Mr. Kahneman is a professor of psychology at Princeton University and the recipient of the 2002 Nobel Prize in economics. Mr. Sibony is a writer and advisor on decision-making processes who teaches at HEC Paris. Mr. Sunstein is the Robert Walmsley University Professor at Harvard University. This essay is adapted from the authors’ new book “Noise: A Flaw in Human Judgment,” which will be published next week by Little Brown.