The article explores the discussion regarding individual decision-making, which tends to be mediated by each subject's perception of reality. These decisions, therefore, are taken based on a deficient or incomplete information about reality. This affects decision in criminal and security policy too, because such policies are not necessarily a correlate of what actually happens, but rather respond to what is perceived. The relevance that a perception of something has in the decision about it would be crucial, because is the first element taken into account during knowledge- and concept-building.