A recent study on mood has some interesting things to say about its value as an evolutionary tool. We’re all aware that one’s mood can affect the way they view things. Everything seems better when you’re in a good mood, or worse in a bad mood. Generally, people tend to think this is bad, or disadvantageous, because it leads to you make decisions based not on the facts, but on your interpretation of them.
But according to the study, our mood can help us adapt to changing circumstances. They offer the example of a trader on the stock exchange, who experiences an unexpected gain. As such, her mood is improved and, now feeling better about things, she might take further risks that could work out. If those risks don’t work out they’ll likely sour her mood and she’ll be more cautious.
The idea is that mood is directly correlated to reward, and the more a person is rewarded, the more likely they are to seek additional reward. Meanwhile, when that reward is small or the person suffers a loss, they are less likely to pursue actions that are likely to result in a similar loss. Essentially, in this model, mood not only allows us to adapt to change, it also drives us to embrace or reject that change accordingly.
When reward drops off though, mood returns to normal, the mood only lasts until the expectation of rewards is met. Which is why people return to a baseline after a high, or a low. The problem with bad moods, though, is that they can begin a downward spiral, wherein every bad thing worsens the mood, which in turns means things are interpreted as worse than they are. These kinds of spirals can lead to depressive episodes, or even lead to long-term depression.