A good first step for learning about a new topic is to identify a single influential article from that field and read it. This can be challenging because such articles often assume that the reader will be familiar with the topic already, and you'll have a lot of questions. But when you finish, you'll be equipped with an understanding of the key terms, concepts, and unsolved problems for the field, and can then choose where to focus next.
Most of the readings are review articles from journals like Annual Review of Psychology. Several of the readings are chapters from the textbook Neuroeconomics (Glimcher and Fehr, Eds.). Three of the readings are primary research articles.