From ABC Science, 4 November 2015:
Moods, both positive and negative, may actually serve an evolutionary purpose in helping us to have more realistic expectations.
Researchers have used mathematical modelling to show that our mood may be a subconscious way for us to keep track of the availability of rewards in our environment, and to tailor our expectations and behaviour accordingly.
And two principles of mood — that it is shaped by how expectations match up with outcomes, and that it in turn influences how we perceive outcomes — may in fact be connected, argue Dr Eran Eldar and colleagues in Trends in Cognitive Sciences today.
“Mood mostly reflects how outcomes differ from expectations, so whether things are going better or worse than what’s expected,” said Dr Eldar from the University College London.
“Mood also affects how we perceive outcomes, so if we’re in a good mood, outcomes seem better than when we’re in a bad mood.”
Dr Eldar suggested that where the availability of multiple sources of reward is connected, and this availability fluctuates over time, mood helps us to adapt to these changes. Read more.