Core affect is a way of thinking about emotional mood state in terms of two measures: valence (from positive to negative) and arousal (from highly active to placid). So if you’re super ticked off about something, that’s negative valence and high arousal, where if you’re just blissfully chill, you’re low arousal and positive valence. But people aren’t just in one state forever–much more interesting is the way that they change.
Zita Oravecz and I look at the dynamics of core affect change within an individual in a recent paper: Associations Between Slow- and Fast-Timescale Indicators of Emotional Functioning in the journal Social Psychological and Personality Science. There, we characterize the changes in core affect within a person in terms of a person’s home base in each dimension, the state they drop back to when there’s no real input, how much they fluctuate around that home base, how strongly their system regulates itself back to base, and the correlations between the ways those characteristics show up in valence and arousal. Importantly, these characteristics turn out to be predictive of other “trait-level” characteristics, like the strategies you use when you have to deal with negative emotion.