The decision to grant a prisoner parole is not something to be taken lightly. It should be considered as seriously and objectively as possible. As a new study of Israeli judges shows, however, these decisions are influenced by a lot more than the lofty ideals of justice. They're also influenced by snacks.

The researchers investigated the percentage of parole cases that were given favorable rulings. They found that as mornings wore on, the judges became less favorable. But after a meal break, they became more favorable again--followed by the same downward trajectory. The Economist has a figure that says it all: Hungry judges give less favorable rulings.

Perhaps it's not surprising that people get grumpy when they are hungry. (There's even a term for it: hangry.) But two things are interesting here. First, hunger had huge effects on a decision that should be, and presumably was, taken very seriously. The scale of the finding itself is pretty amazing. Second, like the judges in the study, most of us underestimate the effect hunger has on on behavior. This both curious and fascinating. Here are two reasons why it happens. 

Correspondence Bias
We don't pay attention to hunger because of the correspondence bias (aka the fundamental attribution error). I assume you do things because of who you are, not because of environmental influences. If I see you drive over a curb, I assume you're a terrible driver; I don't attribute your mistake to the screaming kids in the back seat. (If I drive over the same curb the next day, though, I blame the kids in my backseat.) 

The correspondence bias makes me ignore the fact that you are hungry when I make judgments about you. This can make me think you're a jerk when you're really just grumpy. But it's more insidious: If I'm hungry, I might think you're a jerk because I'm grumpy, but I'll attribute the problem to you. If we weren't subject to correspondence bias, we might be more aware of how internal states like hunger affect us.

Self-Experimentation
Record some data! That's what one of my undergraduate professors, Allen Neuringer, used to tell me. If you start to examine your own life, he promised, you'll see patterns that are often obvious as soon as you start to pay attention. And he was right. 

For example, inspired to record some data, one day I counted the strokes it took me to swim a lap in the pool. Every trip across the pool took exactly 21 strokes, no matter how fast I swam. I had no idea it was that consistent. The same was true when I counted steps on a treadmill; my pace (i.e., footfalls per second) remained basically constant regardless of how fast I was running.

These are not hidden signals among a complex web of information. Yet I had never noticed them. Hunger can be like that. We underestimate it because we don't pay attention to it. Just ask the judges. 

Pay attention to how your body affects your mind. You can learn a lot. For me, being hot, hungry, and tired is the worst. That's probably true of most people and it's not exactly groundbreaking. The important thing is to be aware of it, and to try to control yourself. And to recognize that people around you are probably not themselves if they're hot, tired and hungry too. It might make you a better person, and it might improve your relationships too.

No doubt judges who hear parole requests are suddenly becoming aware of how much hunger affects them. We could all benefit from doing the same.

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