Can Dogs, Reactions and Fears Be Constructed?

Can people's emotions be conditioned? Dogs, reactions and fears are usually about things we know aren't going to hurt them like cars going by. But with people, it's more logic. It's actually the same. You can absolutely condition emotions with people. That's why you sit down and eat ice cream when you're upset. And some people go out and spend money because it gives them a jolt of happiness.