Fast and Frugal decision trees have the characteristic that at every stage of the decision tree, a choice is made. This “heuristic” approach allows for very compact, easy to understand decision making processes within the grasp of unaided humans to execute, and with results that are surprisingly powerful especially in the presence of bounds on search time and costs of decision making.
Fast-and-frugal trees were defined by Martignon and colleagues as decision trees with exactly two branches extending from each node, where either one or both branches is an exit branch leading to a leaf (Martignon et al., 2008, 2003). In other words, in an FFT one answer (or in the case of the final node, both answers) to every question posed by a node will trigger an immediate decision. Because FFTs have an exit branch on every node, they typically make decisions faster than standard decision trees (to avoid confusion, we refer to decision trees that are not fast-and-frugal as standard) while simultaneously being easier to understand and use.
The paper on Categorization with limited resources: A family of simple heuristics (Martignon, 2008) is at Citeseer.