It’s long been known that mood biases our judgments and perceptions, but this effect has usually been regarded as irrational or disadvantageous. A new theory published November 3 in Trends in Cognitive Sciences argues that mood draws on experiences and can, in fact, help us quickly adapt to changes in our environment. For example, experiencing unexpected gains on the stock market should improve a trader’s mood. That positive mood may then cause the trader to take more risks, essentially helping her adapt more quickly to a market that is generally on the rise.
According to the new theory, as people learn from experiences that are colored by their mood, their expectations come to reflect not only the reward associated with each particular state (such as each stock), but also recent changes in the overall availability of reward in their environment. In this way, the existence of mood allows learning to account for the impact of general environmental factors.