Economic experiments have long operated with a de facto ban on the use of deception. For example, a well-known book on experimental methodology from two decades ago (Friedman and Sunder, 1994, p. 17) unambiguously states, “Do not deceive subjects or lie to them.” The ban certainly far precedes these books and likely dates back to early experiments by Vernon Smith and Charles Plott.1 This is generally taken to encompass instructions or materials that actively mislead subjects by stating or strongly implying something that is not true. Common examples include telling subjects that they are playing games versus another subject when they are actually playing a confederate of the experimenter (or a computerized robot), paying subjects based on something other than the announced rules, or resolving random outcomes in a manner inconsistent with announced rules. Deception is generally considered a sin of commission rather than omission, so other experimental techniques that could arguably be classified as deception are considered acceptable. Examples include the use of deliberate ambiguity, where parts of the rules are not specified, not telling subjects what will happen in future portions of the experiment in cases where this information would likely affect current decisions, and using predetermined random draws. In none of these cases has the experimenter directly led the subject to believe something that is false.