Hazard and risk analysis depends heavily on human decision making in the form of engineering judgment and expert opinion. Human decision making may be flawed by the effects of heuristics and cognitive biases. The influence of these psychological factors may invalidate the results of hazard and risk analysis studies. They must be managed carefully to minimize their possible adverse impacts. This article provides a pragmatic view of cognitive biases and guidance on how to address them in hazard and risk analysis. (C) 2017 American Institute of Chemical Engineers