Emotions are apparently simpler than we think. Psychologist James Russell, as quoted in Lisa Feldman Barrett’s new book How Emotions Are Made (2018), came up with a very simple model that describes affect, or how we feel throughout our days.

It has two features only: how pleasant or unpleasant we feel (called valence) and how calm or agitated we feel (called arousal.) Every moment of every day of our life we are somewhere on this sphere. Exactly where we stand depends on our brain’s prediction of our body’s energy needs. It also depends on our closest companions, who bizzarly contribute to regulating our heartbeats, brainwaves, breathing, and other signals.

The crazy thing is, where we stand on the sphere determines how we think about the world. If we are hungry, we are on the unpleasant side, and judge others more harshly. A famous analysis of Israel parole judges found them to be systematically harsher right before lunch. Interviewers apparently are less impressed on rainy days.

What happens when you tend to live in different parts of this ‘moon’ than your closest companion? Do you each drag each other in unfamiliar craters?