Air traffic controllers are generally individuals who are well organized, are quick with numeric computations and mathematics, have assertive and firm decision making skills, are able to maintain 'their cool' and composure under pressure, and possess an excellent short-term memory. Through numerous studies throughout the decades, it has been successfully demonstrated that traffic controllers usually have a superior visual memory, and in addition, studies have shown that air traffic controllers generally have a degree of situational awareness that is significantly better than the population average. In 'games' involving short-term memory, peer-induced stresses, and real-time risk analysis, air traffic control specialists scored better than the control group in every experiment. Excellent hearing and speaking skills are a requirement, and trainees undergo rigorous physical and psychological testing.