I take what many consider to be a radically reductionist approach to beliefs. I think they might be related to simple behaviors like Pavlovian and instrumental learning. These processes can be observed in very simple organisms and I try to apply what we know about them to study beliefs.
Central to our understanding of learning, and I argue belief formation, is the concept of salience or importance. We learn and remember information about important events so we can respond appropriately if the same circumstances recur in the future. I think beliefs are one way that such learning and memory is manifest. If beliefs are so central to our comportment in the world, it is clear that there may be disastrous consequences when they are mis-specified.